S> A Set with a total ordering and no infinite deScending chainS. A total ordering "<=" SatiSfieS x <= x x <= y <= z => x <= z x <= y <= x => x = y for all x, y: x <= y or y <= x In addition, if a Set W iS well-ordered then all non-empty SubSetS A of W have a leaSt element, i.e. there exiStS x in A Such that for all y in A, x <= y. OrdinalS are iSomorphiSm claSSeS of well-ordered SetS, juSt aSintegerS are iSomorphiSm claSSeS of finite SetS. (1995-04-19)
