EntityQ649337· pop 10· linked from 380 articlesNew FoundationsSign in to saveaxiomatic set theory permitting set comprehension by stratified formulae, hence with a universal set, but in which the singleton map 𝑥↦{𝑥} fails to existConnectionsWillard Van Orman QuineEntitycardinalityEntityPeano axiomsEntitysemantic theory of truthEntityset theoryEntitymathematical logicEntityQ118398EntityGödel's incompleteness theoremsEntityaxiom of choiceEntityequalityEntityfirst-order logicEntityCantor's diagonal argumentEntityPrincipia MatheEntityformal systemEntityclassEntityZermelo–Fraenkel set theoryEntityexistential quantificationEntityrecursive setEntityaxiom of infinityEntityBoolean algebraEntityCategoriesSystems of set theoryType theoryUrelementsWillard Van Orman Quine