Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. In mathematics, a binary relation R over a set X is transitive if whenever an element a is related to an element b, and b is in turn related to an element c, then a is also related to c. Transitivity is a key property of both partial order relations and equivalence relations. For some time, economists and philosophers believed that preference was a transitive relation; however, there are now mathematical theories that demonstrate that preferences and other significant economic results can be modeled without resorting to this assumption.