TV Everywhere

TV Everywhere (also known as authenticated streaming or authenticated video on-demand) refers to a type of subscription business model wherein access to streaming video content from a television channel requires users to "authenticate" themselves as current subscribers to the channel, via an account provided by their participating pay television provider, in order to access the content.

Under the model, broadcasters offer their customers the ability to access content from their channels through internet-based services and mobile apps—either live or on-demand, as part of their subscription to the service. Time Warner Cable first proposed the concept in 2009; in 2010, many television providers and networks began to roll out TV Everywhere services for their subscribers, including major networks such as TBS and TNT (whose owner, Time Warner, was an early supporter of the concept), ESPN, and HBO among others. Broadcast television networks have also adopted TV Everywhere restrictions for their online content, albeit in a less broad-scale adoption than their cable counterparts.

Television providers and broadcasters have touted the advantages of being able to access content across multiple platforms, including on the internet, and on mobile devices (such as smartphones and tablet computers), as part of their existing television subscription. Upon its establishment, the TV Everywhere concept received criticism for being difficult for end-users to set up, while media activists have criticized the concept for being a paywall that extends the existing oligarchy of the subscription television industry to the internet, and considering it to be collusion against cord cutters—those who drop cable and satellite entirely in favor of accessing content via terrestrial television, the internet, and subscription video on demand (SVOD) services.

## Rationale

TV Everywhere services were developed in an attempt to compete with the market trend of cord cutting, where consumers drop traditional pay television subscriptions in favor of accessing TV content exclusively through over-the-air television and/or online on-demand services, including Hulu, Netflix, YouTube, and other sources. Authenticated streaming and video on-demand services allow traditional television providers to directly compete with these competitors, and add value to existing television subscriptions in an effort to retain subscribers.

In particular, broadcasters and providers have emphasized the use of TV Everywhere services to allow multi-platform access to their content, on devices such as personal computers, smartphones, tablets, digital media players, and video game consoles.

## History

### Precursors

ESPN first introduced a TV Everywhere-like concept with ESPN360, a service which allowed users to stream sports programming from its networks either live or on-demand through a website. However, access to ESPN360 was restricted to the users of internet service providers who had negotiated deals with ESPN to offer the service; a model closer in nature to cable television carriage. Similar tactics were soon used by several other channels, such as NFL Network (who used the technique to restrict access to its Game Extra service for Thursday Night Football) and Epix (an early pioneer of the concept for the premium cable industry). David Preschlack, ESPN's executive vice president for affiliate sales and marketing, foresaw a future in the model, believing that access to exclusive content would soon play a greater role in competition between high-speed internet providers. However, the model was deemed a violation of the principles of net neutrality by some critics.

### Introduction and adoption

In 2009, Time Warner Cable announced an initiative known as TV Everywhere, a set of principles which were "designed to serve as a framework to facilitate deployment of online television content in a way that is consumer friendly, pro-competitive." The concept would enable users of their respective cable television services to access live and on-demand online content from channels that they subscribe to by using an account-based authentication system. TWC CEO Jeffrey Bewkes believed that the TV Everywhere principles were "good concepts" that are "likely to be the general direction for all TV networks and all the distribution connections that are out there." That summer, both TWC and Comcast began trials of services based on the system; Turner Broadcasting was an early supporter of the system, providing access to TBS and TNT content as part of the trials. Comcast officially launched a public beta of its TV Everywhere-based portal, Xfinity Fancast, in December 2009 for all double-play television and internet customers. Afterwards, other providers began to follow suit.

In 2010, broadcasters and television providers began a wider roll-out of TV Everywhere-based services; for the 2010 Winter Olympics, NBC Sports offered live and video on-demand access to events throughout the Games that required users to authenticate for access. Also in February, HBO launched HBO Go, a video on demand service exclusive to HBO subscribers on participating providers. In September 2010, Disney would begin launching an array of TV Everywhere-based services, including WatchESPN (a successor to ESPN360 offered to ESPN television subscribers), and similar apps for Disney Channel and Disney XD.

In August 2011, Fox became the first over-the-air network to restrict on-demand access with a TV Everywhere-based system; "next day" on-demand episodes (either through its website or Hulu, itself a joint venture between Fox, NBC, and ABC at the time) would only be available online to users authenticating themselves as a subscriber to a cable or satellite provider, or those who subscribe to the Hulu Plus service. All other users would be subject to an eight-day delay. On September 1, 2011, fellow Fox property Big Ten Network (a college sports network dedicated to the Big Ten Conference, operated in partnership with Fox Sports) also launched a TV Everywhere service known as BTN2Go.

### Expansion

Matt Strauss, Comcast senior vice president of digital and emerging platforms, considered the 2012 Summer Olympics to be a "watershed" event for TV Everywhere services; NBCUniversal announced that a total of nearly 10 million authenticated devices accessed its online coverage during the Games across both the NBCOlympics.com site and NBC Olympics Live Extra app; in particular, parent company Comcast accounted for 3.3 million devices from 1.5 million users. Following the Games, the app was rebranded as NBC Sports Live Extra.

TV Everywhere services also began to appear in Canada in the early 2010s, with the Canadian launch of HBO Go in 2012, and the 2013 announcement of TV Everywhere services from Bell Media (beginning with Bravo Go, and also including CTV Go) and Shaw Media (beginning with Global). The majority of Canadian broadcasters are vertically integrated; both Bell and Shaw operate internet service providers and national satellite television services.

In May 2013, ABC released its Watch ABC mobile app, which allows viewers on participating providers to access live streams from participating ABC affiliates. In December 2013, ABC confirmed that it would impose a similar restriction to Fox for "next day" on-demand episodes beginning on January 6, 2014, with seven-day exclusivity for authenticated users and Hulu Plus subscribers. NBC unveiled its own plans for a similar TV Everywhere app to its affiliate board in April 2014.

In November 2015, after negotiations surrounding revenue sharing and infrastructural mandates (including a proposed requirement that the games only be available through the league's existing apps), Major League Baseball reached a three-year deal with Fox to allow it to offer in-market online streaming on Fox Sports Go (though streamed using MLB Advanced Media infrastructure) for the 16 teams that it holds regional rights to through the Fox Sports Networks division. In December 2015, Discovery Communications, a long hold-out on the concept, launched Discovery Go, a centralized TV Everywhere service and mobile app for Discovery Channel, TLC, and its array of sister networks.

### Shift to subscription-based services

In the late-2010's, a number of major media companies began to shift their priorities towards direct-to-consumer, subscription-based streaming services, in order to specifically attract cord cutters and increase their competitiveness with competitors such as Netflix and Amazon Prime Video. Some of these forays either subsume content previously distributed via a TV Everywhere model, or represent a hybrid approach of a service that can be obtained direct-to-consumer or via a television provider (through authentication or promotional offers):

- In 2018, ESPN launched ESPN+, which began to subsume much of the overflow content that had previously been available at no extra charge to ESPN subscribers via WatchESPN.
- In 2018, Bell Media merged its OTT service CraveTV with its pay television service The Movie Network, with the merged service taking on the Crave branding and becoming available on a direct-to-consumer basis.
- HBO and NBCUniversal both launched streaming services in 2020, HBO Max and Peacock. HBO Max replaced both HBO Go and a previous direct-to-consumer offering, HBO Now, and is available to HBO subscribers via television providers at no additional charge. Peacock's ad-supported premium tier is similarly offered to television subscribers via agreements with individual providers, such as NBCUniversal parent Comcast.

## Reception

The TV Everywhere concept has been met with mixed reception. Some broadcasters were initially hesitant to introduce TV Everywhere services, with concerns that they might affect advertising revenue and not be adequately counted by Nielsen ratings. Songwriters Guild of America president Rick Carnes praised the TV Everywhere concept and other recent developments for helping to provide easier, legal access to premium content online.

Media activists have criticized the concept as protecting the existing closed, regionalized oligarchy of multichannel television by tying digital content to traditional television subscriptions, thus harming fully over-the-top competitors. Public Knowledge believed that "under the 'TV Everywhere' plan, no other program distributors would be able to emerge, and no consumers will be able to 'cut the cord' because they find what they want online. As a result, consumers will be the losers." A 2010 report by Free Press made similar arguments, contending that TV Everywhere was an act of collusion by the cable industry, and arguing that "by tying programming to local cable subscriptions, while denying content to pure online TV distributors, the incumbent industry hopes to artificially reproduce the lack of competition for TV distribution to which it is accustomed, based on geographical fiefdoms and turf." The NCTA denied many of Free Press' arguments, stating that it was "an effort to ensure more content than ever is distributed over the Internet at no extra charge to consumers."

In July 2014, BTIG analyst Richard Greenfield criticized the video on demand services offered through TV Everywhere systems for being ad-supported. In examples from FX and TNT, he noticed that ads often repeated, and that in TNT's case, its version of an episode of The Last Ship included 20 minutes of unskippable ads across 45 minutes of programming. In conclusion, he contended that viewers would rather wait for programs to appear on subscription streaming services rather than use TV Everywhere services.

### Viewer awareness

Despite efforts by broadcasters to educate viewers on TV Everywhere services and how to utilize them (including Fox, which produced a promotional video starring Jane Lynch as her Glee character Sue Sylvester, describing the process as being less painful than waterboarding), critics and end-users criticized the registration and authentication processes for being frustrating and difficult. In response, providers took steps to improve their user experiences; Disney reported that use of its TV Everywhere services increased after it simply changed its process to use the term "verify" instead of "authenticate", Cablevision, Comcast, and Verizon introduced systems that automatically verify users with their residential gateways, and Synacor (a provider of authentication platforms used by providers) added the ability for users to link their provider account to a social network login, such as Facebook or Twitter.

For the 2012 Summer Olympics and 2014 Winter Olympics, NBC worked closer with providers to help educate users, and produced customized marketing materials and video tutorials featuring Carson Daly (2012) and Ryan Seacrest (2014) to help inform users. As an incentive, NBC also allowed authenticated users to enter a sweepstakes to win a trip to London (2012) or Rio de Janeiro (2014).

Still, with dissatisfaction with the system and the quality of NBC's overall coverage, there was an increase in the use of virtual private network (VPN) services to access the more comprehensive online coverage of the Games being provided by broadcasters in Canada (CTV in London, CBC in Sochi) and the United Kingdom (BBC), which only used geoblocking and did not require TV Everywhere authentication.

In April 2014, the Cable & Telecommunications Association for Marketing (CTAM) unveiled an industry-wide initiative for marketing and educating subscribers about TV Everywhere services provided by broadcasters and providers; these efforts include a stylized "tv everywhere" logo which the organization intends providers to use as a unified brand to denote TV Everywhere services. The logo consists of interlocking rectangles, representing multiple "screens" (platforms) for viewing content. The association also provided design recommendations for TV Everywhere user experiences, aiming to alleviate the confusion that had been experienced by users during the authentication process.

### Adoption

In a December 2013 survey of 4,205 pay television subscribers, NPD Group found that 21% of them used a TV Everywhere service at least once per month, and that 90% of them were satisfied with the experience. NPD analyst Russ Crupnick felt that "aggressive" use of the model was helping to counter cord cutting, which "speaks to the level of engagement they have with programming and a comfort in using the Internet to both access and interact with that programming." The study also found that 3 out of 10 pay television subscribers who were also subscribed to an SVOD service used TV Everywhere services at least once a week (in comparison to 2 out of 10 for those who were not).

Amid criticism of NBC's coverage, adoption of NBC's TV Everywhere services during the 2014 Winter Olympics was still significantly large: on February 21, 2014, coverage of the Men's hockey semi-final featuring the U.S. and Canada recorded the largest Live Extra audience in NBC Sports history, with 2.12 million unique viewers, augmenting the average NBCSN television audience of 3.9 million. ESPN's coverage of the 2014 FIFA World Cup drew similarly heavy online viewership: during a group stage match between the U.S. and Portugal, at least 1.7 million concurrent viewers were using WatchESPN (though, not all of the viewers were necessarily watching the game).

In December 2015, research firm GfK estimated that 53% of the United States' pay television subscribers have used a TV Everywhere service—an increase from 42% in 2012, that overall use had doubled since 2012, and 79% of those surveyed found the login process easy. However, only 25% of those surveyed were aware of the term "TV Everywhere" or the CTAM logo, leading to the firm believing that consumer awareness and education was still a "critical missing piece" in the adoption of these services.

### Platform non-neutrality

In 2014, Comcast was criticized for its decision to arbitrarily block access to HBO Go on PlayStation and Roku devices, but still allowing its use on competing Apple TV and Xbox 360. Comcast similarly blocked access to Showtime Anytime on Roku as well. A spokesperson for the provider stated that "with every new website, device or player we authenticate, we need to work through technical integration and customer service which takes time and resources. Moving forward, we will continue to prioritize as we partner with various players."

During both the FCC's net neutrality hearings and comments regarding Comcast's then-proposed merger with Time Warner Cable (which, by contrast, allows HBO Go access on all supported devices), Roku criticized the provider for contradicting the TV Everywhere concept by discriminating against specific devices, thus prioritizing its own on-demand platform over external services. The company argued that providers could selectively favor certain platforms over others, further stating that "a large and powerful MVPD may use this leverage in negotiations with content providers or operators of streaming platforms, ultimately favoring parties that can either afford to pay for the privilege of authentication, or have other business leverage that can be used as a counterweight to discriminatory authentication."

On December 15, 2014, Comcast enabled the ability to use HBO Go and Showtime Anytime on Roku devices. However, Comcast still blocked HBO Go on PlayStation consoles until December 2016.

### Password sharing

There have been instances of users deliberately sharing their TV Everywhere login credentials, or having them sold without their owner's knowledge on the black market, in order to allow others to view programs without subscribing to the channel. Charter Communications CEO Tom Rutledge, and ESPN's executive vice president for affiliate sales and marketing Justin Connolly, have considered this practice equivalent to piracy. In December 2017, it was reported that television providers and program distributors had begun to implement measures in order to discourage this practice, including reducing the length of login session, reducing the number of concurrent streams allowed on a single account, and monitoring unusual usage patterns such as large numbers of concurrent streams on a single account—especially those originating from outside of the customer's region, or during major programs.

In August 2019, as part of its latest carriage agreement, it was announced that Charter and Disney would "work together to implement business rules and techniques to address such issues as unauthorized access and password sharing."

By contrast, HBO's then-CEO Richard Plepler argued in an interview that intentional password sharing did not impact their business, and was a "marketing vehicle" that could help attract new subscribers, while Netflix CEO Reed Hastings similarly argued that "household sharing leads to new customers because kids subscribe on their own as they start to earn income".

Authentication for streaming video


Khmer language

Khmer (/kəˈmɛər/; ខ្មែរ, UNGEGN: Khmêr ) is an Austroasiatic language spoken by the Khmer people, and the official and national language of Cambodia. Khmer has been influenced considerably by Sanskrit and Pali, especially in the royal and religious registers, through Hinduism and Buddhism. It is also the earliest recorded and earliest written language of the Mon–Khmer family, predating Mon and Vietnamese, due to Old Khmer being the language of the historical empires of Chenla, Angkor and, presumably, their earlier predecessor state, Funan.

The vast majority of Khmer speakers speak Central Khmer, the dialect of the central plain where the Khmer are most heavily concentrated. Within Cambodia, regional accents exist in remote areas but these are regarded as varieties of Central Khmer. Two exceptions are the speech of the capital, Phnom Penh, and that of the Khmer Khe in Stung Treng province, both of which differ sufficiently enough from Central Khmer to be considered separate dialects of Khmer.

Outside of Cambodia, three distinct dialects are spoken by ethnic Khmers native to areas that were historically part of the Khmer Empire. The Northern Khmer dialect is spoken by over a million Khmers in the southern regions of Northeast Thailand and is treated by some linguists as a separate language. Khmer Krom, or Southern Khmer, is the first language of the Khmer of Vietnam, while the Khmer living in the remote Cardamom Mountains speak a very conservative dialect that still displays features of the Middle Khmer language.

Khmer is primarily an analytic, isolating language. There are no inflections, conjugations or case endings. Instead, particles and auxiliary words are used to indicate grammatical relationships. General word order is subject–verb–object, and modifiers follow the word they modify. Classifiers appear after numbers when used to count nouns, though not always so consistently as in languages like Chinese. In spoken Khmer, topic-comment structure is common, and the perceived social relation between participants determines which sets of vocabulary, such as pronouns and honorifics, are proper.

Khmer differs from neighboring languages such as Burmese, Thai, Lao, and Vietnamese in that it is not a tonal language. Words are stressed on the final syllable, hence many words conform to the typical Mon–Khmer pattern of a stressed syllable preceded by a minor syllable. The language has been written in the Khmer script, an abugida descended from the Brahmi script via the southern Indian Pallava script, since at least the 7th century. The script's form and use has evolved over the centuries; its modern features include subscripted versions of consonants used to write clusters and a division of consonants into two series with different inherent vowels.

## Classification

Khmer is a member of the Austroasiatic language family, the autochthonous family in an area that stretches from the Malay Peninsula through Southeast Asia to East India. Austroasiatic, which also includes Mon, Vietnamese and Munda, has been studied since 1856 and was first proposed as a language family in 1907. Despite the amount of research, there is still doubt about the internal relationship of the languages of Austroasiatic.

Diffloth places Khmer in an eastern branch of the Mon-Khmer languages. In these classification schemes Khmer's closest genetic relatives are the Bahnaric and Pearic languages. More recent classifications doubt the validity of the Mon-Khmer sub-grouping and place the Khmer language as its own branch of Austroasiatic equidistant from the other 12 branches of the family.

## Geographic distribution and dialects

Khmer is spoken by some 13 million people in Cambodia, where it is the official language. It is also a second language for most of the minority groups and indigenous hill tribes there. Additionally there are a million speakers of Khmer native to southern Vietnam (1999 census) and 1.4 million in northeast Thailand (2006).

Khmer dialects, although mutually intelligible, are sometimes quite marked. Notable variations are found in speakers from Phnom Penh (Cambodia's capital city), the rural Battambang area, the areas of Northeast Thailand adjacent to Cambodia such as Surin province, the Cardamom Mountains, and southern Vietnam. The dialects form a continuum running roughly north to south. Standard Cambodian Khmer is mutually intelligible with the others but a Khmer Krom speaker from Vietnam, for instance, may have great difficulty communicating with a Khmer native of Sisaket Province in Thailand.

The following is a classification scheme showing the development of the modern Khmer dialects.

- Middle Khmer
  - Cardamom (Western) Khmer
  - Central Khmer
    - Surin (Northern) Khmer
    - Standard Khmer and related dialects (including Khmer Krom)

Standard Khmer, or Central Khmer, the language as taught in Cambodian schools and used by the media, is based on the dialect spoken throughout the Central Plain, a region encompassed by the northwest and central provinces.

Northern Khmer (called Khmer Surin in Khmer) refers to the dialects spoken by many in several border provinces of present-day northeast Thailand. After the fall of the Khmer Empire in the early 15th century, the Dongrek Mountains served as a natural border leaving the Khmer north of the mountains under the sphere of influence of the Kingdom of Lan Xang. The conquests of Cambodia by Naresuan the Great for Ayutthaya furthered their political and economic isolation from Cambodia proper, leading to a dialect that developed relatively independently from the midpoint of the Middle Khmer period.

This has resulted in a distinct accent influenced by the surrounding tonal languages Lao and Thai, lexical differences, and phonemic differences in both vowels and distribution of consonants. Syllable-final , which has become silent in other dialects of Khmer, is still pronounced in Northern Khmer. Some linguists classify Northern Khmer as a separate but closely related language rather than a dialect.

Western Khmer, also called Cardamom Khmer or Chanthaburi Khmer, is spoken by a very small, isolated population in the Cardamom mountain range extending from western Cambodia into eastern Central Thailand. Although little studied, this variety is unique in that it maintains a definite system of vocal register that has all but disappeared in other dialects of modern Khmer.

Phnom Penh Khmer is spoken in the capital and surrounding areas. This dialect is characterized by merging or complete elision of syllables, which speakers from other regions consider a "relaxed" pronunciation. For instance, "Phnom Penh" is sometimes shortened to "m'Penh". Another characteristic of Phnom Penh speech is observed in words with an "r" either as an initial consonant or as the second member of a consonant cluster (as in the English word "bread"). The "r", trilled or flapped in other dialects, is either pronounced as a uvular trill or not pronounced at all.

This alters the quality of any preceding consonant, causing a harder, more emphasized pronunciation. Another unique result is that the syllable is spoken with a low-rising or "dipping" tone much like the "hỏi" tone in Vietnamese. For example, some people pronounce ត្រី ('fish') as : the is dropped and the vowel begins by dipping much lower in tone than standard speech and then rises, effectively doubling its length. Another example is the word រៀន ('study'), which is pronounced , with the uvular "r" and the same intonation described above.

Khmer Krom or Southern Khmer is spoken by the indigenous Khmer population of the Mekong Delta, formerly controlled by the Khmer Empire but part of Vietnam since 1698. Khmers are persecuted by the Vietnamese government for using their native language and, since the 1950s, have been forced to take Vietnamese names. Consequently, very little research has been published regarding this dialect. It has been generally influenced by Vietnamese for three centuries and accordingly displays a pronounced accent, tendency toward monosyllabic words and lexical differences from Standard Khmer.

Khmer Khe is spoken in the Se San, Srepok and Sekong river valleys of Sesan and Siem Pang districts in Stung Treng Province. Following the decline of Angkor, the Khmer abandoned their northern territories, which the Lao then settled. In the 17th century, Chey Chetha XI led a Khmer force into Stung Treng to retake the area. The Khmer Khe living in this area of Stung Treng in modern times are presumed to be the descendants of this group. Their dialect is thought to resemble that of pre-modern Siem Reap.

## Historical periods

Linguistic study of the Khmer language divides its history into four periods one of which, the Old Khmer period, is subdivided into pre-Angkorian and Angkorian. Pre-Angkorian Khmer is the Old Khmer language from 600 CE through 800. Angkorian Khmer is the language as it was spoken in the Khmer Empire from the 9th century until the 13th century.

The following centuries saw changes in morphology, phonology and lexicon. The language of this transition period, from about the 14th to 18th centuries, is referred to as Middle Khmer and saw borrowings from Thai in the literary register. Modern Khmer is dated from the 19th century to today.

The following table shows the conventionally accepted historical stages of Khmer.

Just as modern Khmer was emerging from the transitional period represented by Middle Khmer, Cambodia fell under the influence of French colonialism. Thailand, which had for centuries claimed suzerainty over Cambodia and controlled succession to the Cambodian throne, began losing its influence on the language. In 1887 Cambodia was fully integrated into French Indochina, which brought in a French-speaking aristocracy. This led to French becoming the language of higher education and the intellectual class. By 1907, the French had wrested over half of modern-day Cambodia, including the north and northwest where Thai had been the prestige language, back from Thai control and reintegrated it into the country.

Many native scholars in the early 20th century, led by a monk named Chuon Nath, resisted the French and Thai influences on their language. Forming the government sponsored Cultural Committee to define and standardize the modern language, they championed Khmerization, purging of foreign elements, reviving affixation, and the use of Old Khmer roots and historical Pali and Sanskrit to coin new words for modern ideas. Opponents, led by Keng Vannsak, who embraced "total Khmerization" by denouncing the reversion to classical languages and favoring the use of contemporary colloquial Khmer for neologisms, and Ieu Koeus, who favored borrowing from Thai, were also influential.

Koeus later joined the Cultural Committee and supported Nath. Nath's views and prolific work won out and he is credited with cultivating modern Khmer-language identity and culture, overseeing the translation of the entire Pali Buddhist canon into Khmer. He also created the modern Khmer language dictionary that is still in use today, helping preserve Khmer during the French colonial period.

## Phonology

The phonological system described here is the inventory of sounds of the standard spoken language, represented using the International Phonetic Alphabet (IPA).

### Consonants

The voiceless plosives may occur with or without aspiration (as vs. , etc.); this difference is contrastive before a vowel. However, the aspirated sounds in that position may be analyzed as sequences of two phonemes: . This analysis is supported by the fact that infixes can be inserted between the stop and the aspiration; for example ('big') becomes ('size') with a nominalizing infix. When one of these plosives occurs initially before another consonant, aspiration is no longer contrastive and can be regarded as mere phonetic detail: slight aspiration is expected when the following consonant is not one of (or if the initial plosive is ).

The voiced plosives are pronounced as implosives by most speakers, but this feature is weak in educated speech, where they become .

In syllable-final position, and approach and respectively. The stops are unaspirated and have no audible release when occurring as syllable finals.

In addition, the consonants , , and occur occasionally in recent loan words in the speech of Cambodians familiar with French and other languages.

### Vowels

Various authors have proposed slightly different analyses of the Khmer vowel system. This may be in part because of the wide degree of variation in pronunciation between individual speakers, even within a dialectal region. The description below follows Huffman (1970). The number of vowel nuclei and their values vary between dialects; differences exist even between the Standard Khmer system and that of the Battambang dialect on which the standard is based.

In addition, some diphthongs and triphthongs are analyzed as a vowel nucleus plus a semivowel ( or ) coda because they cannot be followed by a final consonant. These include: (with short monophthongs) , , , , ; (with long monophthongs) , ; (with long diphthongs) , , , , and .

### Syllable structure

A Khmer syllable begins with a single consonant, or else with a cluster of two, or rarely three, consonants. The only possible clusters of three consonants at the start of a syllable are , and (with aspirated consonants analyzed as two-consonant sequences) . There are 85 possible two-consonant clusters (including [ph] etc. analyzed as /ph/ etc.). All the clusters are shown in the following table, phonetically, i.e. superscript h can mark either contrastive or non-contrastive aspiration (see above).

Slight vowel epenthesis occurs in the clusters consisting of a plosive followed by , in those beginning , and in the cluster .

After the initial consonant or consonant cluster comes the syllabic nucleus, which is one of the vowels listed above. This vowel may end the syllable or may be followed by a coda, which is a single consonant. If the syllable is stressed and the vowel is short, there must be a final consonant. All consonant sounds except and the aspirates can appear as the coda (although final /r/ is heard in some dialects, most notably in Northern Khmer).

A minor syllable (unstressed syllable preceding the main syllable of a word) has a structure of CV-, CrV-, CVN- or CrVN- (where C is a consonant, V a vowel, and N a nasal consonant). The vowels in such syllables are usually short; in conversation they may be reduced to , although in careful or formal speech, including on television and radio, they are clearly articulated. An example of such a word is មនុស្ស mɔnuh, mɔnɨh, mĕəʾnuh ('person'), pronounced , or more casually .

### Stress

Stress in Khmer falls on the final syllable of a word. Because of this predictable pattern, stress is non-phonemic in Khmer (it does not distinguish different meanings).

Most Khmer words consist of either one or two syllables. In most native disyllabic words, the first syllable is a minor (fully unstressed) syllable. Such words have been described as sesquisyllabic (i.e. as having one-and-a-half syllables). There are also some disyllabic words in which the first syllable does not behave as a minor syllable, but takes secondary stress. Most such words are compounds, but some are single morphemes (generally loanwords). An example is ភាសា ('language'), pronounced .

Words with three or more syllables, if they are not compounds, are mostly loanwords, usually derived from Pali, Sanskrit, or more recently, French. They are nonetheless adapted to Khmer stress patterns. Primary stress falls on the final syllable, with secondary stress on every second syllable from the end. Thus in a three-syllable word, the first syllable has secondary stress; in a four-syllable word, the second syllable has secondary stress; in a five-syllable word, the first and third syllables have secondary stress, and so on. Long polysyllables are not often used in conversation.

Compounds, however, preserve the stress patterns of the constituent words. Thus សំបុកចាប, the name of a kind of cookie (literally 'bird's nest'), is pronounced , with secondary stress on the second rather than the first syllable, because it is composed of the words ('nest') and ('bird').

### Phonation and tone

Khmer once had a phonation distinction in its vowels, but this now survives only in the most archaic dialect (Western Khmer). The distinction arose historically when vowels after Old Khmer voiced consonants became breathy voiced and diphthongized; for example became . When consonant voicing was lost, the distinction was maintained by the vowel (); later the phonation disappeared as well (). These processes explain the origin of what are now called a-series and o-series consonants in the Khmer script.

Although most Cambodian dialects are not tonal, the colloquial Phnom Penh dialect has developed a tonal contrast (level versus peaking tone) as a by-product of the elision of .

### Intonation

Intonation often conveys semantic context in Khmer, as in distinguishing declarative statements, questions and exclamations. The available grammatical means of making such distinctions are not always used, or may be ambiguous; for example, the final interrogative particle ទេ can also serve as an emphasizing (or in some cases negating) particle.

The intonation pattern of a typical Khmer declarative phrase is a steady rise throughout followed by an abrupt drop on the last syllable.

ខ្ញុំមិនចង់បានទេ       ('I don't want it')

Other intonation contours signify a different type of phrase such as the "full doubt" interrogative, similar to yes–no questions in English. Full doubt interrogatives remain fairly even in tone throughout, but rise sharply towards the end.

អ្នកចង់ទៅលេងសៀមរាបទេ       ('do you want to go to Siem Reap?')

Exclamatory phrases follow the typical steadily rising pattern, but rise sharply on the last syllable instead of falling.

សៀវភៅនេះថ្លៃណាស់       ('this book is expensive!')

## Grammar

Khmer is primarily an analytic language with no inflection. Syntactic relations are mainly determined by word order. Old and Middle Khmer used particles to mark grammatical categories and many of these have survived in Modern Khmer but are used sparingly, mostly in literary or formal language. Khmer makes extensive use of auxiliary verbs, "directionals" and serial verb construction. Colloquial Khmer is a zero copula language, instead preferring predicative adjectives (and even predicative nouns) unless using a copula for emphasis or to avoid ambiguity in more complex sentences. Basic word order is subject–verb–object (SVO), although subjects are often dropped; prepositions are used rather than postpositions.

Topic-Comment constructions are common and the language is generally head-initial (modifiers follow the words they modify). Some grammatical processes are still not fully understood by western scholars. For example, it is not clear if certain features of Khmer grammar, such as actor nominalization, should be treated as a morphological process or a purely syntactic device, and some derivational morphology seems "purely decorative" and performs no known syntactic work.

Lexical categories have been hard to define in Khmer. Henri Maspero, an early scholar of Khmer, claimed the language had no parts of speech, while a later scholar, Judith Jacob, posited four parts of speech and innumerable particles. John Haiman, on the other hand, identifies "a couple dozen" parts of speech in Khmer with the caveat that Khmer words have the freedom to perform a variety of syntactic functions depending on such factors as word order, relevant particles, location within a clause, intonation and context. Some of the more important lexical categories and their function are demonstrated in the following example sentence taken from a hospital brochure:

### Morphology

Modern Khmer is an isolating language, which means that it uses little productive morphology. There is some derivation by means of prefixes and infixes, but this is a remnant of Old Khmer and not always productive in the modern language. Khmer morphology is evidence of a historical process through which the language was, at some point in the past, changed from being an agglutinative language to adopting an isolating typology. Affixed forms are lexicalized and cannot be used productively to form new words. Below are some of the most common affixes with examples as given by Huffman.

Compounding in Khmer is a common derivational process that takes two forms, coordinate compounds and repetitive compounds. Coordinate compounds join two unbound morphemes (independent words) of similar meaning to form a compound signifying a concept more general than either word alone. Coordinate compounds join either two nouns or two verbs. Repetitive compounds, one of the most productive derivational features of Khmer, use reduplication of an entire word to derive words whose meaning depends on the class of the reduplicated word. A repetitive compound of a noun indicates plurality or generality while that of an adjectival verb could mean either an intensification or plurality.

Coordinate compounds:

{\| style="width:25%;"

\| \|\| + \|\| \|\| ⇒ \|\| \|- \| "father" \|\| \|\| "mother" \|\| ⇒ \|\| "parents"

{\| style="width:25%;"

\| \|\| + \|\| \|\| ⇒ \|\| \|- \| "to transport" \|\| \|\| "to bring" \|\| ⇒ \|\| "to lead"

Repetitive compounds:

{\| style="width:40%;"

\| \|\| ⇒ \|\| \|\| \|\| \|\| ⇒ \|\| \|- \| "fast" \|\| \|\| "very fast, quickly" \|\| \|\| "women" \|\| \|\| "women, women in general"

#### Nouns and pronouns

Khmer nouns do not inflect for grammatical gender or singular/plural. There are no articles, but indefiniteness is often expressed by the word for "one" (មួយ ) following the noun as in ឆ្កែមួយ ( "a dog"). Plurality can be marked by postnominal particles, numerals, or reduplication of a following adjective, which, although similar to intensification, is usually not ambiguous due to context.

{\|

\| \|style="width:20%; text-align: center"\| or \| \|style="width:20%; text-align: center"\| or \|

Classifying particles are used after numerals, but are not always obligatory as they are in Thai or Chinese, for example, and are often dropped in colloquial speech. Khmer nouns are divided into two groups: mass nouns, which take classifiers; and specific, nouns, which do not. The overwhelming majority are mass nouns.

Possession is colloquially expressed by word order. The possessor is placed after the thing that is possessed. Alternatively, in more complex sentences or when emphasis is required, a possessive construction using the word របស់ (, "property, object") may be employed. In formal and literary contexts, the possessive particle នៃ () is used:

{\|

\| \| style="width:20%; text-align: center" \| or \| \| style="width:20%; text-align: center" \| or \|

Pronouns are subject to a complicated system of social register, the choice of pronoun depending on the perceived relationships between speaker, audience and referent (see Social registers below). Khmer exhibits pronoun avoidance, so kinship terms, nicknames and proper names are often used instead of pronouns (including for the first person) among intimates. Subject pronouns are frequently dropped in colloquial conversation.

Adjectives, verbs and verb phrases may be made into nouns by the use of nominalization particles. Three of the more common particles used to create nouns are , , and . These particles are prefixed most often to verbs to form abstract nouns. The latter, derived from Sanskrit, also occurs as a suffix in fixed forms borrowed from Sanskrit and Pali such as ("health") from ("to be healthy").

{\|

\| \| style="width:20%; text-align: center" \| \| \| style="width:20%; text-align: center" \| \|

#### Adjectives and adverbs

Adjectives, demonstratives and numerals follow the noun they modify. Adverbs likewise follow the verb. Morphologically, adjectives and adverbs are not distinguished, with many words often serving either function. Adjectives are also employed as verbs as Khmer sentences rarely use a copula.

Degrees of comparison are constructed syntactically. Comparatives are expressed using the word ជាង : "A X [B]" (A is more X [than B]). The most common way to express superlatives is with ជាងគេ : "A X " (A is the most X). Intensity is also expressed syntactically, similar to other languages of the region, by reduplication or with the use of intensifiers.

{\|

\| \| style="width:15%; text-align: center" \| \| \| style="width:15%; text-align: center" \| \|

#### Verbs

As is typical of most East Asian languages, Khmer verbs do not inflect at all; tense, aspect and mood can be expressed using auxiliary verbs, particles (such as កំពុង , placed before a verb to express continuous aspect) and adverbs (such as "yesterday", "earlier", "tomorrow"), or may be understood from context. Serial verb construction is quite common.

Khmer verbs are a relatively open class and can be divided into two types, main verbs and auxiliary verbs. Huffman defined a Khmer verb as "any word that can be (negated)", and further divided main verbs into three classes.

Transitive verbs are verbs that may be followed by a direct object:

{\|

\| \| style="width:20%; text-align: center" \| \|

Intransitive verbs are verbs that can not be followed by an object:

{\|

\| \| style="width:20%; text-align: center" \| \|

Adjectival verbs are a word class that has no equivalent in English. When modifying a noun or verb, they function as adjectives or adverbs, respectively, but they may also be used as main verbs equivalent to English "be + adjective".

{\|

! Adjective: \| style="width:20%; text-align: center" \| ! Adverb: \| style="width:20%; text-align: center" \| ! Verb: \|- \| \| \| \| \|

### Syntax

Syntax is the rules and processes that describe how sentences are formed in a particular language, how words relate to each other within clauses or phrases and how those phrases relate to each other within a sentence to convey meaning. Khmer syntax is very analytic. Relationships between words and phrases are signified primarily by word order supplemented with auxiliary verbs and, particularly in formal and literary registers, grammatical marking particles. Grammatical phenomena such as negation and aspect are marked by particles while interrogative sentences are marked either by particles or interrogative words equivalent to English "wh-words".

A complete Khmer sentence consists of four basic elements—an optional topic, an optional subject, an obligatory predicate, and various adverbials and particles. The topic and subject are noun phrases, predicates are verb phrases and another noun phrase acting as an object or verbal attribute often follows the predicate.

#### Basic constituent order

When combining these noun and verb phrases into a sentence the order is typically SVO:

{\| style="width:25%;"

\| \|\| \|\| \|\| \|\| \|- \| sbj \|\| verb\|\| obj \|\| \|- \| I \|\| give \|\| banana \|\| one \|\| bunch[clf] \|- \| colspan=5 \| 'I gave a bunch of bananas.'

When both a direct object and indirect object are present without any grammatical markers, the preferred order is SV(DO)(IO). In such a case, if the direct object phrase contains multiple components, the indirect object immediately follows the noun of the direct object phrase and the direct object's modifiers follow the indirect object:

{\| style="width:25%;"

\| \|\| \|\| \|\| \|\| \|\| \|- \| sbj \|\| verb\|\| dir obj\|\| ind obj \|\| \|- \| I \|\| give \|\| banana \|\| pig \|\| one \|\| bunch[clf] \|- \| colspan=6 \| 'I gave the pig a bunch of bananas.'

This ordering of objects can be changed and the meaning clarified with the inclusion of particles. The word , which normally means "to arrive" or "towards", can be used as a preposition meaning "to":

{\| style="width:25%;"

\| \|\| \|\| \|\| \|\| \|\| \|\| \|- \| I \|\| give \|\| banana \|\| one \|\| bunch[clf] \|\| toward \|\| pig \|- \| colspan=7 \| 'I gave a bunch of bananas to the pigs.'

Alternatively, the indirect object could precede the direct object if the object-marking preposition were used:

{\| style="width:25%;"

\| \|\| \|\| \|\| \|\| \|\| \|\| \|- \| I \|\| give \|\| pig \|\| obj marker \|\| banana \|\| one \|\| bunch[clf] \|- \| colspan=7 \| 'I gave the pig a bunch of bananas.'

However, in spoken discourse OSV is possible when emphasizing the object in a topic–comment-like structure.

{\| style="width:25%;"

\| \|\| \|\| \|\| \|\| \|- \| boat \|\| one \|\| to sit \|\| five \|\| monk[clf] \|- \| colspan=5 \| 'In a boat sit five monks.'

{\| style="width:25%;"

\| \|\| \|\| \|\| \|\| \|- \| science \|\| thief \|\| to steal \|\| neg \|\| compl \|- \| colspan=5 \| 'Science, a thief can not steal.'

#### Noun phrase

The noun phrase in Khmer typically has the following structure:

Noun Phrase = (Honorific) Noun (Adjectival modifiers) (Numeral) (Classifier) (Demonstrative)

The elements in parentheses are optional. Honorifics are a class of words that serve to index the social status of the referent. Honorifics can be kinship terms or personal names, both of which are often used as first and second person pronouns, or specialized words such as ('god') before royal and religious objects. The most common demonstratives are ('this, these') and ('that, those'). The word ('those over there') has a more distal or vague connotation.

If the noun phrase contains a possessive adjective, it follows the noun and precedes the numeral. If a descriptive attribute co-occurs with a possessive, the possessive construction () is expected.

Some examples of typical Khmer noun phrases are:

{\| class="wikitable"

\|- ! Khmer text !! IPA !! gloss !! translation \|- \| ផ្ទះស្កឹមស្កៃបីបួនខ្នងនេះ \|\| \|\| house high three four spine[clf] these
noun adj num num classifier dem \|\| 'these three or four high houses' \|- \| ចេកទុំពីរស្និតនេះ \|\| \|\| banana ripe two bunches[clf] these
noun adj num classifier dem \|\| these two bunches of ripe bananas \|- \| ពួកម៉ាកខ្ញុំពីរនាក់នេះ \|\| \|\| friend I two person[clf] these
noun poss num classifier dem \|\| these two friends of mine \|- \| ពួកម៉ាកតូចរបស់ខ្ញុំពីរនាក់នេះ \|\| \|\| friend small of I two person[clf] these
noun adj poss num classifier dem \|\| these two small friends of mine

The Khmer particle marked attributes in Old Khmer noun phrases and is used in formal and literary language to signify that what precedes is the noun and what follows is the attribute. Modern usage may carry the connotation of mild intensity.

{\| style="width:25%;"

\| \|\| \|\| \|\| \|- \| field \|\| paddy \|\| adj marker \|\| vast \|- \| colspan=4 \| '(very) expansive fields and paddies'

#### Verb phrase

Khmer verbs are completely uninflected, and once a subject or topic has been introduced or is clear from context the noun phrase may be dropped. Thus, the simplest possible sentence in Khmer consists of a single verb. For example, 'to go' on its own can mean "I'm going.", "He went.", "They've gone.", "Let's go.", etc. This also results in long strings of verbs such as:

{\| style="width:25%;"

\| \|\| \|\| \|\| \|\| \|- \| I \|\| to want \|\| to go \|\| to walk \|\| to play \|- \| colspan=5 \| 'I want to go for a stroll.'

Khmer uses three verbs for what translates into English as the copula. The general copula is ; it is used to convey identity with nominal predicates. For locative predicates, the copula is . The verb is the "existential" copula meaning "there is" or "there exists".

{\| style="width:35%;"

\| \|\| \|\| \|\| \|\| \|\| \|\| \|\| \|- \| language \|\| copula \|\| nmlz \|\| to express \|\| heart \|\| thought \|\| all \|\| kind \|- \| colspan=8 \| 'Language is the expression of all emotions and ideas'

{\| style="text-align: left;"

\| \|\| \|\| \|\| \|\| style="width:30%; text-align: center" \|   \|\| \|\| \|- \| he \|\| copula \|\| close \|\| temple \|\| style="width:30%; text-align: center" \|   \|\| to exist \|\| plan \|- \| colspan=4 \| 'He is close to the temple.' \|\| style="width:30%; text-align: center" \|   \|\| colspan=2 \| 'There is a plan.'

Negation is achieved by putting មិន before the verb and the particle ទេ at the end of the sentence or clause. In colloquial speech, verbs can also be negated without the need for a final particle, by placing ឥត before them.

{\| style="text-align: left;"

\| \|\| \|\| style="width:15%; text-align: center" \|   \|\| \|\| \|\| \|\| \|\| style="width:15%; text-align: center" \|   \|\| \|\| \|\| \|- \| I \|\| to believe \|\| style="width:15%; text-align: center" \|   \|\| I \|\| neg \|\| to believe \|\| neg \|\| style="width:15%; text-align: center" \|   \|\| I \|\| neg \|\| to believe \|- \| colspan=2 \| 'I believe.' \|\| style="width:15%; text-align: center" \|   \|\| colspan=4 \| 'I don't believe.' \|\| style="width:15%; text-align: center" \|   \|\| colspan=3 \| 'I don't believe.'

Past tense can be conveyed by adverbs, such as "yesterday" or by the use of perfective particles such as

{\| style="text-align: left;"

\| \|\| \|\| \|\| style="width:30%; text-align: center" \|   \|\| \|\| \|\| \|- \| he \|\| to go \|\| yesterday \|\| style="width:30%; text-align: center" \|   \|\| he \|\| to go \|\| pfv \|- \| colspan=3 \| 'He went yesterday.' \|\| style="width:30%; text-align: center" \|   \|\| colspan=3 \| 'He left.' or 'He's already gone.'

Different senses of future action can also be expressed by the use of adverbs like "tomorrow" or by the future tense marker , which is placed immediately before the verb, or both:

{\| style="width:35%;"

\| \|\| \|\| \|\| \|\| \|- \| tomorrow \|\| I \|\| fut \|\| to go \|\| school \|- \| colspan=5 \| 'Tomorrow, I will go to school.'

Imperatives are often unmarked. For example, in addition to the meanings given above, the "sentence" can also mean "Go!". Various words and particles may be added to the verb to soften the command to varying degrees, including to the point of politeness (jussives):

{\| style="text-align: left;"

\| \|\| \|\| \|\| \|\| \|\| \|\| ''style="width:30%; text-align: center" \|   \|\| \|\| \|\| \|\| \|\| \|\| \|- \| imp \|\| try \|\| try \|\| you \|\| refl \|\| imp \|\| style="width:30%; text-align: center" \|   \|\| please \|\| do \|\| follow \|\| instruction \|\| he \|\| imp \|- \| colspan=6 \| 'Go ahead and try it yourself.' \|\| style="width:30%; text-align: center" \|   \|\| colspan=6 \| 'Please follow his instructions.'

Prohibitives take the form " + verb" and also are often softened by the addition of the particle to the end of the phrase.

{\| style="width:35%;"

\| \|\| \|\| \|\| \|\| \|- \| proh \|\| to be \|\| place \|\| dem \|\| cohortative \|- \| colspan=5 \| 'Don't stay in this place.'

#### Questions

There are three basic types of questions in Khmer. Questions requesting specific information use question words. Polar questions are indicated with interrogative particles, most commonly , a homonym of the negation particle. Tag questions are indicated with various particles and rising inflection. The SVO word order is generally not inverted for questions.

{\| style="text-align: left;"

\| \|\| \|\| \|\| style="width:10%; text-align: center" \|   \|\| \|\| \|\| \|\| \|\| style="width:10%; text-align: center" \|   \|\| \|\| \|\| \|\| \|\| \|\| \|- \| you \|\| to go \|\| where \|\| style="width:10%; text-align: center" \|   \|\| you \|\| understand \|\| modal \|\| q \|\| style="width:10%; text-align: center" \|   \|\| you \|\| to go \|\| market \|\| prf \|\| or \|\| yet \|- \| colspan=3 \| 'Where are you going?' \|\| style="width:10%; text-align: center" \|   \|\| colspan=4 \| 'Can you understand?' \|\| style="width:10%; text-align: center" \|   \|\| colspan=7 \| 'Have you gone to the store yet?'

In more formal contexts and in polite speech, questions are also marked at their beginning by the particle .

{\| style="width:25%;"

\| \|\| \|\| \|\| \|\| \|- \| q \|\| you \|\| to invite \|\| to go \|\| where \|- \| colspan=5 \| 'Where are you going, sir?'

#### Passive voice

Khmer does not have a passive voice, but there is a construction utilizing the main verb ("to hit", "to be correct", "to affect") as an auxiliary verb meaning "to be subject to" or "to undergo"—which results in sentences that are translated to English using the passive voice.

{\| style="width:25%;"

\| \|\| \|\| \|\| \|\| \|\| \|- \| from \|\| yesterday \|\| I \|\| to undergo \|\| dog \|\| to bite \|- \| colspan=6 \| 'Yesterday I was bitten by a dog.'

#### Clause syntax

Complex sentences are formed in Khmer by the addition of one or more clauses to the main clause. The various types of clauses in Khmer include the coordinate clause, the relative clause and the subordinate clause. Word order in clauses is the same for that of the basic sentences described above. Coordinate clauses do not necessarily have to be marked; they can simply follow one another. When explicitly marked, they are joined by words similar to English conjunctions such as ("and") and ("and then") or by clause-final conjunction-like adverbs and , both of which can mean "also" or "and also"; disjunction is indicated by ("or").

Relative clauses can be introduced by ("that") but, similar to coordinate clauses, often simply follow the main clause. For example, both phrases below can mean "the hospital bed that has wheels".

{\| style="text-align: left;"

\| \|\| \|\| \|\| \|\| \|\| style="width:20%; text-align: center" \|   \|\| \|\| \|\| \|\| \|\| \|\| \|- \| bed \|\| hospital \|\| have \|\| wheel \|\| to push \|\| style="width:20%; text-align: center" \|   \|\| bed \|\| hospital \|\| rel \|\| have \|\| wheel \|\| to push

Relative clauses are more likely to be introduced with if they do not immediately follow the head noun. Khmer subordinate conjunctions always precede a subordinate clause. Subordinate conjunctions include words such as ("because"), ("seems as if") and ("in order to").

## Numerals

Counting in Khmer is based on a biquinary system: the numbers from 6 to 9 have the form "five one", "five two", etc. The words for multiples of ten from 30 to 90 are not related to the basic Khmer numbers, but are Chinese in origin, and probably came to Khmer via Thai. Khmer numerals, which were inherited from Indian numerals, are used more widely than Western Arabic numerals.

The principal number words are listed in the following table, which gives Western and Khmer digits, Khmer spelling and IPA transcription.

Intermediate numbers are formed by compounding the above elements. Powers of ten are denoted by loan words: រយ rôy (100), ពាន់ poăn (1,000), ម៉ឺន mœn (10,000), សែន sên (100,000) and លាន léan (1,000,000) from Thai and កោដិ kaôdĕ (10,000,000) from Sanskrit.

Ordinal numbers are formed by placing the particle ទី ti before the corresponding cardinal number.

## Social registers

Khmer employs a system of registers in which the speaker must always be conscious of the social status of the person spoken to. The different registers, which include those used for common speech, polite speech, speaking to or about royals and speaking to or about monks, employ alternate verbs, names of body parts and pronouns. As an example, the word for "to eat" used between intimates or in reference to animals is . Used in polite reference to commoners, it is . When used of those of higher social status, it is or . For monks the word is and for royals, . Another result is that the pronominal system is complex and full of honorific variations, just a few of which are shown in the table below.

## Writing system

Khmer is written with the Khmer script, an abugida developed from the Pallava script of India before the 7th century when the first known inscription appeared. Written left-to-right with vowel signs that can be placed after, before, above or below the consonant they follow, the Khmer script is similar in appearance and usage to Thai and Lao, both of which were based on the Khmer system. The Khmer script is also distantly related to the Mon–Burmese script. Within Cambodia, literacy in the Khmer alphabet is estimated at 77.6%.

Consonant symbols in Khmer are divided into two groups, or series. The first series carries the inherent vowel while the second series carries the inherent vowel . The Khmer names of the series, ('voiceless') and ('voiced'), respectively, indicate that the second series consonants were used to represent the voiced phonemes of Old Khmer. As the voicing of stops was lost, however, the contrast shifted to the phonation of the attached vowels, which, in turn, evolved into a simple difference of vowel quality, often by diphthongization. This process has resulted in the Khmer alphabet having two symbols for most consonant phonemes and each vowel symbol having two possible readings, depending on the series of the initial consonant:

## Examples

The following text is from Article 1 of the Universal Declaration of Human Rights.

## See also

- Hem Chieu
- Khmer literature
- Romanization of Khmer

## References and notes

Austroasiatic language of Cambodia


Borromean rings

In mathematics, the Borromean rings are three simple closed curves in three-dimensional space that are topologically linked and cannot be separated from each other, but that break apart into two unknotted and unlinked loops when any one of the three is cut or removed. Most commonly, these rings are drawn as three circles in the plane, in the pattern of a Venn diagram, alternatingly crossing over and under each other at the points where they cross. Other triples of curves are said to form the Borromean rings as long as they are topologically equivalent to the curves depicted in this drawing.

The Borromean rings are named after the Italian House of Borromeo, who used the circular form of these rings as an element of their coat of arms, but designs based on the Borromean rings have been used in many cultures, including by the Norsemen and in Japan. They have been used in Christian symbolism as a sign of the Trinity, and in modern commerce as the logo of Ballantine beer, giving them the alternative name Ballantine rings. Physical instances of the Borromean rings have been made from linked DNA or other molecules, and they have analogues in the Efimov state and Borromean nuclei, both of which have three components bound to each other although no two of them are bound.

Geometrically, the Borromean rings may be realized by linked ellipses, or (using the vertices of a regular icosahedron) by linked golden rectangles. It is impossible to realize them using circles in three-dimensional space, but it has been conjectured that they may be realized by copies of any non-circular simple closed curve in space. In knot theory, the Borromean rings can be proved to be linked by counting their Fox n-colorings. As links, they are Brunnian, alternating, algebraic, and hyperbolic. In arithmetic topology, certain triples of prime numbers have analogous linking properties to the Borromean rings.

## Definition and notation

It is common in mathematics publications that define the Borromean rings to do so as a link diagram, a drawing of curves in the plane with crossings marked to indicate which curve or part of a curve passes above or below at each crossing. Such a drawing can be transformed into a system of curves in three-dimensional space by embedding the plane into space and deforming the curves drawn on it above or below the embedded plane at each crossing, as indicated in the diagram. The commonly-used diagram for the Borromean rings consists of three equal circles centered at the points of an equilateral triangle, close enough together that their interiors have a common intersection (such as in a Venn diagram or the three circles used to define the Reuleaux triangle). Its crossings alternate between above and below when considered in consecutive order around each circle; another equivalent way to describe the over-under relation between the three circles is that each circle passes over a second circle at both of their crossings, and under the third circle at both of their crossings. Two links are said to be equivalent if there is a continuous deformation of space (an ambient isotopy) taking one to another, and the Borromean rings may refer to any link that is equivalent in this sense to the standard diagram for this link.

In The Knot Atlas, the Borromean rings are denoted with the code "L6a4"; the notation means that this is a link with six crossings and an alternating diagram, the fourth of five alternating 6-crossing links identified by Morwen Thistlethwaite in a list of all prime links with up to 13 crossings. In the tables of knots and links in Dale Rolfsen's 1976 book Knots and Links, extending earlier listings in the 1920s by Alexander and Briggs, the Borromean rings were given the Alexander–Briggs notation "6", meaning that this is the second of three 6-crossing 3-component links to be listed. The Conway notation for the Borromean rings, ".1", is an abbreviated description of the standard link diagram for this link.

## History and symbolism

The name "Borromean rings" comes from the use of these rings, in the form of three linked circles, in the coat of arms of the aristocratic Borromeo family in Northern Italy. The link itself is much older and has appeared in the form of the valknut, three linked equilateral triangles with parallel sides, on Norse image stones dating back to the 7th century. The Ōmiwa Shrine in Japan is also decorated with a motif of the Borromean rings, in their conventional circular form. A stone pillar in the 6th-century Marundeeswarar Temple in India shows three equilateral triangles rotated from each other to form a regular enneagram; like the Borromean rings these three triangles are linked and not pairwise linked, but this crossing pattern describes a different link than the Borromean rings.

The Borromean rings have been used in different contexts to indicate strength in unity. In particular, some have used the design to symbolize the Trinity. A 13th-century French manuscript depicting the Borromean rings labeled as unity in trinity was lost in a fire in the 1940s, but reproduced in an 1843 book by Adolphe Napoléon Didron. Didron and others have speculated that the description of the Trinity as three equal circles in canto 33 of Dante's Paradiso was inspired by similar images, although Dante does not detail the geometric arrangement of these circles. The psychoanalyst Jacques Lacan found inspiration in the Borromean rings as a model for his topology of human subjectivity, with each ring representing a fundamental Lacanian component of reality (the "real", the "imaginary", and the "symbolic").

The rings were used as the logo of Ballantine beer, and are still used by the Ballantine brand beer, now distributed by the current brand owner, the Pabst Brewing Company. For this reason they have sometimes been called the "Ballantine rings".

The first work of knot theory to include the Borromean rings was a catalog of knots and links compiled in 1876 by Peter Tait. In recreational mathematics, the Borromean rings were popularized by Martin Gardner, who featured Seifert surfaces for the Borromean rings in his September 1961 "Mathematical Games" column in Scientific American. In 2006, the International Mathematical Union decided at the 25th International Congress of Mathematicians in Madrid, Spain to use a new logo based on the Borromean rings.

### Partial and multiple rings

In medieval and renaissance Europe, a number of visual signs consist of three elements interlaced together in the same way that the Borromean rings are shown interlaced (in their conventional two-dimensional depiction), but with individual elements that are not closed loops. Examples of such symbols are the Snoldelev stone horns and the Diana of Poitiers crescents.

Some knot-theoretic links contain multiple Borromean rings configurations; one five-loop link of this type is used as a symbol in Discordianism, based on a depiction in the Principia Discordia.

## Mathematical properties

### Linkedness

In knot theory, the Borromean rings are a simple example of a Brunnian link, a link that cannot be separated but that falls apart into separate unknotted loops as soon as any one of its components is removed. There are infinitely many Brunnian links, and infinitely many three-curve Brunnian links, of which the Borromean rings are the simplest.

There are a number of ways of seeing that the Borromean rings are linked. One is to use Fox n-colorings, colorings of the arcs of a link diagram with the integers modulo n so that at each crossing, the two colors at the undercrossing have the same average (modulo n) as the color of the overcrossing arc, and so that at least two colors are used. The number of colorings meeting these conditions is a knot invariant, independent of the diagram chosen for the link. A trivial link with three components has $n^3-n$ colorings, obtained from its standard diagram by choosing a color independently for each component and discarding the $n$ colorings that only use one color. For standard diagram of the Borromean rings, on the other hand, the same pairs of arcs meet at two undercrossings, forcing the arcs that cross over them to have the same color as each other, from which it follows that the only colorings that meet the crossing conditions violate the condition of using more than one color. Because the trivial link has many valid colorings and the Borromean rings have none, they cannot be equivalent.

The Borromean rings are an alternating link, as their conventional link diagram has crossings that alternate between passing over and under each curve, in order along the curve. They are also an algebraic link, a link that can be decomposed by Conway spheres into 2-tangles. They are the simplest alternating algebraic link which does not have a diagram that is simultaneously alternating and algebraic. It follows from the Tait conjectures that the crossing number of the Borromean rings (the fewest crossings in any of their link diagrams) is 6, the number of crossings in their alternating diagram.

### Ring shape

The Borromean rings are typically drawn with their rings projecting to circles in the plane of the drawing, but three-dimensional circular Borromean rings are an impossible object: it is not possible to form the Borromean rings from circles in three-dimensional space. More generally proved using four-dimensional hyperbolic geometry that no Brunnian link can be exactly circular. For three rings in their conventional Borromean arrangement, this can be seen from considering the link diagram. If one assumes that two of the circles touch at their two crossing points, then they lie in either a plane or a sphere. In either case, the third circle must pass through this plane or sphere four times, without lying in it, which is impossible. Another argument for the impossibility of circular realizations, by Helge Tverberg, uses inversive geometry to transform any three circles so that one of them becomes a line, making it easier to argue that the other two circles do not link with it to form the Borromean rings.

However, the Borromean rings can be realized using ellipses. These may be taken to be of arbitrarily small eccentricity: no matter how close to being circular their shape may be, as long as they are not perfectly circular, they can form Borromean links if suitably positioned. A realization of the Borromean rings by three mutually perpendicular golden rectangles can be found within a regular icosahedron by connecting three opposite pairs of its edges. Every three unknotted polygons in Euclidean space may be combined, after a suitable scaling transformation, to form the Borromean rings. If all three polygons are planar, then scaling is not needed. In particular, because the Borromean rings can be realized by three triangles, the minimum number of sides possible for each of its loops, the stick number of the Borromean rings is nine.

More generally, Matthew Cook has conjectured that any three unknotted simple closed curves in space, not all circles, can be combined without scaling to form the Borromean rings. After Jason Cantarella suggested a possible counterexample, Hugh Nelson Howards weakened the conjecture to apply to any three planar curves that are not all circles. On the other hand, although there are infinitely many Brunnian links with three links, the Borromean rings are the only one that can be formed from three convex curves.

### Ropelength

In knot theory, the ropelength of a knot or link is the shortest length of flexible rope (of radius one) that can realize it. Mathematically, such a realization can be described by a smooth curve whose radius-one tubular neighborhood avoids self-intersections. The minimum ropelength of the Borromean rings has not been proven, but the smallest value that has been attained is realized by three copies of a 2-lobed planar curve. Although it resembles an earlier candidate for minimum ropelength, constructed from four circular arcs of radius two, it is slightly modified from that shape, and is composed from 42 smooth pieces defined by elliptic integrals, making it shorter by a fraction of a percent than the piecewise-circular realization. It is this realization, conjectured to minimize ropelength, that was used for the International Mathematical Union logo. Its length is $\approx 58.006$, while the best proven lower bound on the length is $12\pi\approx 37.699$.

For a discrete analogue of ropelength, the shortest representation using only edges of the integer lattice, the minimum length for the Borromean rings is exactly $36$. This is the length of a representation using three $2\times 4$ integer rectangles, inscribed in Jessen's icosahedron in the same way that the representation by golden rectangles is inscribed in the regular icosahedron.

### Hyperbolic geometry

The Borromean rings are a hyperbolic link: the space surrounding the Borromean rings (their link complement) admits a complete hyperbolic metric of finite volume. Although hyperbolic links are now considered plentiful, the Borromean rings were one of the earliest examples to be proved hyperbolic, in the 1970s, and this link complement was a central example in the video Not Knot, produced in 1991 by the Geometry Center.

Hyperbolic manifolds can be decomposed in a canonical way into gluings of hyperbolic polyhedra (the Epstein–Penner decomposition) and for the Borromean complement this decomposition consists of two ideal regular octahedra. The volume of the Borromean complement is $16\Lambda(\pi/4)=8G \approx 7.32772\dots$ where $\Lambda$ is the Lobachevsky function and $G$ is Catalan's constant. The complement of the Borromean rings is universal, in the sense that every closed 3-manifold is a branched cover over this space.

### Number theory

In arithmetic topology, there is an analogy between knots and prime numbers in which one considers links between primes. The triple of primes (13, 61, 937) are linked modulo 2 (the Rédei symbol is −1) but are pairwise unlinked modulo 2 (the Legendre symbols are all 1). Therefore, these primes have been called a "proper Borromean triple modulo 2" or "mod 2 Borromean primes".

## Physical realizations

A monkey's fist knot is essentially a 3-dimensional representation of the Borromean rings, albeit with three layers, in most cases. Sculptor John Robinson has made artworks with three equilateral triangles made out of sheet metal, linked to form Borromean rings and resembling a three-dimensional version of the valknut. A common design for a folding wooden tripod consists of three pieces carved from a single piece of wood, with each piece consisting of two lengths of wood, the legs and upper sides of the tripod, connected by two segments of wood that surround an elongated central hole in the piece. Another of the three pieces passes through each of these holes, linking the three pieces together in the Borromean rings pattern. Tripods of this form have been described as coming from Indian or African hand crafts.

In chemistry, molecular Borromean rings are the molecular counterparts of Borromean rings, which are mechanically-interlocked molecular architectures. In 1997, biologist Chengde Mao and coworkers of New York University succeeded in constructing a set of rings from DNA. In 2003, chemist Fraser Stoddart and coworkers at UCLA utilised coordination chemistry to construct a set of rings in one step from 18 components. Borromean ring structures have been used to describe noble metal clusters shielded by a surface layer of thiolate ligands. A library of Borromean networks has been synthesized by design by Giuseppe Resnati and coworkers via halogen bond driven self-assembly. In order to access the molecular Borromean ring consisting of three unequal cycles a step-by-step synthesis was proposed by Jay S. Siegel and coworkers.

In physics, a quantum-mechanical analog of Borromean rings is called a halo state or an Efimov state, and consists of three bound particles that are not pairwise bound. The existence of such states was predicted by physicist Vitaly Efimov, in 1970, and confirmed by multiple experiments beginning in 2006. This phenomenon is closely related to a Borromean nucleus, a stable atomic nucleus consisting of three groups of particles that would be unstable in pairs. Another analog of the Borromean rings in quantum information theory involves the entanglement of three qubits in the Greenberger–Horne–Zeilinger state.

Three linked but pairwise separated rings