Answers.Body: <p>Before trying to explain this term in your context, let me briefly describe the term in other contexts.</p>
  
  <p>In computer networking, the term "hop" refers to a node (e.g. a router) that a packet goes through before reaching its destination from its source. In a multi-hop situation, you have several nodes involved in the process of sending the packet from the source to the destination.</p>
  
  <p>A <a href="https://arxiv.org/pdf/2003.02320.pdf" rel="nofollow noreferrer">knowledge graph</a> is a graph that accumulates and conveys knowledge of the real world, where nodes represent entities of interest and edges relations between those entities.</p>
  
  <p>So, multi-hop relational paths are probably relational paths involving more than one node or edge in the knowledge graph. </p>
  
  <p><em>But what do we mean by "relational"?</em></p>
  
  <p>If you are familiar with the basics of databases, the word "relational" shouldn't be so unfamiliar. In fact, there the so-called <a href="https://en.wikipedia.org/wiki/Relational_database" rel="nofollow noreferrer">relational databases</a>, <a href="https://en.wikipedia.org/wiki/Relational_model" rel="nofollow noreferrer">relational models</a> and <a href="https://en.wikipedia.org/wiki/Relational_algebra" rel="nofollow noreferrer">relational algebra</a>. Intuitively, the word "relational" is used to denote what you think it denotes, i.e. relations. See also <a href="https://www.oracle.com/database/what-is-a-relational-database/" rel="nofollow noreferrer">What a relational database is</a> by Oracle.</p>
  
  <p><em>And what is a path?</em></p>
  
  <p>In section 2.2.3 of the tutorial <a href="https://arxiv.org/pdf/2003.02320.pdf#page=10" rel="nofollow noreferrer">Knowledge Graphs</a>, Aidan Hogan et al. provide a description of a path (expressions) in the context of knowledge graphs</p>
  
  <blockquote>
    <p>Navigational graph patterns. A key feature that distinguishes graph query languages is the ability to include path expressions in queries. A path expression <span class="math-container">$r$</span> is a regular expression that allows matching arbitrary-length paths between two nodes, which is expressed as a regular path query <span class="math-container">$(x,r,y)$</span>, where <span class="math-container">$x$</span> and <span class="math-container">$y$</span> can be variables or constants (or even the same term).</p>
  </blockquote>
  
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Body: <p>What are multi-hop relational paths in the context of knowledge graphs (KGs)?</p>
  
  <p>I tried looking it up online, but didn't find a simple explanation.</p>
  
Tags: <recommender-system><knowledge-graph>
Title: What are multi-hop relational paths?
UserDisplayName: stoic-santiago
ThreadText: # What are multi-hop relational paths?
  
  (Asked by: username_0 on 2020-05-02)
  
  What are multi-hop relational paths in the context of knowledge graphs (KGs)?
  
  I tried looking it up online, but didn't find a simple explanation.
  
  **Tags:** recommender-system, knowledge-graph
  
  
  ---
  
  ## 1 answers
  
  ### Answer by username_1 on 2020-05-02. Score: 1 | Accepted answer
  
  Before trying to explain this term in your context, let me briefly describe the term in other contexts.
  
  In computer networking, the term "hop" refers to a node (e.g. a router) that a packet goes through before reaching its destination from its source. In a multi-hop situation, you have several nodes involved in the process of sending the packet from the source to the destination.
  
  A [knowledge graph](https://arxiv.org/pdf/2003.02320.pdf) is a graph that accumulates and conveys knowledge of the real world, where nodes represent entities of interest and edges relations between those entities.
  
  So, multi-hop relational paths are probably relational paths involving more than one node or edge in the knowledge graph.
  
  *But what do we mean by "relational"?*
  
  If you are familiar with the basics of databases, the word "relational" shouldn't be so unfamiliar. In fact, there the so-called [relational databases](https://en.wikipedia.org/wiki/Relational_database), [relational models](https://en.wikipedia.org/wiki/Relational_model) and [relational algebra](https://en.wikipedia.org/wiki/Relational_algebra). Intuitively, the word "relational" is used to denote what you think it denotes, i.e. relations. See also [What a relational database is](https://www.oracle.com/database/what-is-a-relational-database/) by Oracle.
  
  *And what is a path?*
  
  In section 2.2.3 of the tutorial [Knowledge Graphs](https://arxiv.org/pdf/2003.02320.pdf#page=10), Aidan Hogan et al. provide a description of a path (expressions) in the context of knowledge graphs
  
  > Navigational graph patterns. A key feature that distinguishes graph query languages is the ability to include path expressions in queries. A path expression $r$ is a regular expression that allows matching arbitrary-length paths between two nodes, which is expressed as a regular path query $(x,r,y)$, where $x$ and $y$ can be variables or constants (or even the same term).
  
  
  ---
  
  