Partial order set( Poset) Definition Given a set a and a relation R on it < AR> is called a partially ordered set( poset in brief)if R is reflexive, antisymmetric and transitivePartial order set(Poset) Definition Given a set A and a relation R on it, < A, R > is called a partially ordered set(poset in brief) if R is reflexive, antisymmetric and transitive. Yi Li (Fudan University) Discrete Mathematics February 28, 2012 4 / 15