Lévy hierarchy (English, name)
expansion: the Lévy hierarchy
Senses:
topics: human-sciences
logic
mathematics
philosophy
sciences
set-theory
glosses: A hierarchy of formulas in the formal language of the Zermelo-Fraenkel set theory. Its first level contains only formulas with no unbounded quantifiers and is denoted by Δ₀=Σ₀=Π₀. Subsequent levels are given by finding a formula in prenex normal form which is provably equivalent over ZFC, and counting the number of changes of quantifiers.
Forms:
form: the Lévy hierarchy
tags: canonical