Number theory
While the word "algorithm" goes back only to certain readers of al-Khwārizmī, careful descriptions of methods of solution are older than proofs: such methods (that is, algorithms) are as old as any recognisable mathematics—ancient Egyptian, Babylonian, Vedic, Chinese—whereas proofs appeared only with the Greeks of the classical period.
An interesting early case is that of what we now call the Euclidean algorithm. In its basic form (namely, as an algorithm for computing the greatest common divisor) it appears as Proposition 2 of Book VII in "Elements", together with a proof of correctness. However, in the form that is often used in number theory (namely, as an algorithm for finding integer solutions to an equation formula_78,
or, what is the same, for finding the quantities whose existence is assured by the Chinese remainder theorem) it first appears in the works of Āryabhaṭa (5th–6th century CE) as an algorithm called
"kuṭṭaka" ("pulveriser"), without a proof of correctness.
Introduction to Algorithms
The first edition of the textbook did not include Stein as an author, and thus the book became known by the initialism CLR. It included two chapters ("Arithmetic Circuits" & "Algorithms for Parallel Computers") that were dropped in the second edition. After the addition of the fourth author in the second edition, many began to refer to the book as "CLRS". This first edition of the book was also known as "The Big White Book (of Algorithms)." With the second edition, the predominant color of the cover changed to green, causing the nickname to be shortened to just "The Big Book (of Algorithms)." A third edition was published in August 2009. Plans for the next edition started in 2014, but the fourth edition will be published in 2019 the earliest, and likely later than that.