(definition)

**Definition:**
A *relation* between exactly two items at a time, such as "greater than" (>), "not equal to" (≠), "proper subset of" (⊂), or "is connected to" (has an *edge* to) for *vertices* of a *graph*.

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

*relation*.

**Specialization** (... is a kind of me.)

*dictionary*.

**See also**
*binary function*, *reflexive*, *symmetric*, *transitive*, *antisymmetric*, *irreflexive*.

*Note:
One may think of a binary relation as a binary function whose range is {true, false}. For example since 3 > 2, GreaterThan(3, 2) = true.*

Author: PEB

Go to the Dictionary of Algorithms and Data Structures home page.

If you have suggestions, corrections, or comments, please get in touch with Paul E. Black.

Entry modified 15 October 2004.

HTML page formatted Fri Mar 25 16:20:34 2011.

Cite this as:

Paul E. Black, "binary relation", in
*Dictionary of Algorithms and Data
Structures* [online], Paul E. Black, ed.,
U.S. National Institute of
Standards and Technology. 15 October 2004. (accessed TODAY)
Available from: http://www.nist.gov/dads/HTML/binaryRelation.html