Wessex in classical heraldry and is found on a number of church windows in derived shields such as the Arms of the Collegiate Church of St Peter at Westminster (Westminster Abbey, which was founded by the king). At its greatest extent Wessex encompassed the modern areas of Hampshire, Isle of Wight, Dorset and Wiltshire, as well as the western half of Berkshire and the eastern hilly flank of Somerset. This covers an area of about . The English author Thomas Hardy used a fictionalised Wessex as a setting for many of his novels, adopting his friend William Barnes' term "Wessex" for
S (set theory) a set "x" whose members are just those sets satisfying "A"("y"). The role of "Spec" in S is analogous to that of the axiom schema of specification of Z. Boolos’s name for Zermelo set theory minus extensionality was "Z-". Boolos derived in S all axioms of "Z-" except the axiom of choice. The purpose of this exercise was to show how most of conventional set theory can be derived from the iterative conception of set, assumed embodied in S. Extensionality does not follow from the iterative conception, and so is not a theorem of S. However, S + Extensionality is