partial order


Definition: An order defined for some, but not necessarily all, pairs of items. For instance, the sets {a, b} and {a, c, d} are subsets of {a, b, c, d}, but neither is a subset of the other. So "subset of" is a partial order on sets.

Formal Definition: A partial order is a binary relation that is reflexive, transitive, and antisymmetric.

See also total order, poset.

Authors: PEB,PJT

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Entry modified 17 December 2004.
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Cite this as:
Paul E. Black and Paul J. Tanenbaum, "partial order", in Dictionary of Algorithms and Data Structures [online], Paul E. Black, ed. 17 December 2004. (accessed TODAY) Available from: