'''Relation theory''', or the '''theory of relations''', treats the subject matter of [[relation]]s in its combinatorial aspect, as distinguished from, though related to, its more properly logical study on one side and its more generally mathematical study on another. | '''Relation theory''', or the '''theory of relations''', treats the subject matter of [[relation]]s in its combinatorial aspect, as distinguished from, though related to, its more properly logical study on one side and its more generally mathematical study on another. |