partition division of a set into mutually exclusive and jointly exhaustive subsets. Derivatively, ‘partition’ can mean any set P whose members are mutually exclusive and jointly exhaustive subsets of set S. Each subset of a partition P is called a partition class of S with respect to P. Partitions are intimately associated with equivalence relations, i.e. with relations that are transitive, symmetric, and reflexive. Given an equivalence relation R defined on a set S, R induces a partition P of S in the following natural way: members s and s belong to the same partition class of Jesuit casuistry and the persecution of the Jansenists for their purported adherence to five propositions in Jansen’s Augustinus. Pascal’s philosophical contributions are found throughout his work, but primarily in his Pensées (1670), an intended apology for Christianity left incomplete and fragmentary at his death. The influence of the Pensées on religious thought and later existentialism has been profound because P if and only if s has the relation R to . Conversely, given a partition P of a set S, P induces an equivalence relation R defined on S in the following natural way: members s and s are such fragments were sewn together in clusters; many others were left unorganized, but recent scholthat s has the relation R to s if and only if s and s belong to the same partition class of P. For obvious reasons, then, partition classes are also known as equivalence classes. See also RELATION, SET THEOR. R.W.B.