binary relation - on sets S and T. A subset of S*T, say R. When T=S, we refer to just the relation on the set S.
Here are 5 properties that distinguish relations on a set (x, y, z are in S):
antisymmetric - (x, y) in R and x not= y imply (y, x) not in R.
irreflexive - (x, x) not in R.
reflexive - (x, x) in R.
symmetric - (x, y) in R implies (y, x) in R.
transitive - (x, y) and (y, z) in R imply (x, z) in R;
дс тдрлими цюлютдажкию дроемжки аиакиохдйис лидр
http://carbon.cudenver.edu/~hgreenbe/glossary/B.html;
