A linear extension of a Partially Ordered Set is a Permutation of the elements , , ... of such that Implies . For example, the linear extensions of the Partially Ordered Set are 1234, 1324, 1342, 3124, 3142, and 3412, all of which have 1 before 2 and 3 before 4.

**References**

Brightwell, G. and Winkler, P. ``Counting Linear Extensions.'' *Order* **8**, 225-242, 1991.

Preusse, G. and Ruskey, F. ``Generating Linear Extensions Fast.'' *SIAM J. Comput.* **23**, 373-386, 1994.

Ruskey, F. ``Information on Linear Extension.'' http://sue.csc.uvic.ca/~cos/inf/pose/LinearExt.html.

Varol, Y. and Rotem, D. ``An Algorithm to Generate All Topological Sorting Arrangements.'' *Comput. J.*
**24**, 83-84, 1981.

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1999-05-25