A Relation ``'' is a partial order on a Set if it has:
See also Antichain, Chain, Fence Poset, Ideal (Partial Order), Length (Partial Order), Linear Extension, Partially Ordered Set, Total Order, Width (Partial Order)
References
Ruskey, F. ``Information on Linear Extension.''
http://sue.csc.uvic.ca/~cos/inf/pose/LinearExt.html.