Lévy hierarchy
专有名词
英文释义
专有名词
- 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.
词形变化
词源
Introduced by Azriel Lévy in 1965.
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数据来源: Wiktionary