This document discusses binary relations and their properties. A binary relation R from sets A to B is a subset of the Cartesian product A × B. Relations can be represented using matrices, where the (i,j) entry is 1 if the element (i,j) is in the relation and 0 otherwise. The properties of relations discussed include: reflexive (an element is related to itself), symmetric (if a is related to b then b is related to a), antisymmetric (if a is related to b and b is related to a then a=b), and transitive (if a is related to b and b is related to c then a is related to c). Boolean operations can be used on the matrices