(definition)

**Definition:**
Two *vertices* of a *graph* are adjacent if there is an *edge* between them. Two *edges* of a graph are adjacent if they connect the same vertex.

**Generalization** (I am a kind of ...)

*binary relation*.

*Note:
The "adjacent" relation is symmetric, but not (necessarily) reflexive or transitive.*

Author: PEB

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Entry modified 4 November 2004.

HTML page formatted Mon Feb 2 13:10:39 2015.

Cite this as:

Paul E. Black, "adjacent", in
*Dictionary of Algorithms and Data Structures* [online], Vreda Pieterse and Paul E. Black, eds. 4 November 2004. (accessed TODAY)
Available from: http://www.nist.gov/dads/HTML/adjacent.html