Wessex the ensuing Norman Conquest of England, and as the Norman kings soon did away with the great earldoms of the late Anglo-Saxon period, 1066 marks the extinction of Wessex as a political unit. From the second edition (1989) of the "Oxford English Dictionary": Wessex 1. The name of a kingdom in south-west England in Anglo-Saxon times, used by Thomas Hardy as the name of the county in which his stories are set (corresponding approximately to Dorset, Somerset, Hampshire, and Wiltshire) and since used as a name for south-west England or this part of it. Wessex is often symbolised by a
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