Definition of Lightface. Meaning of Lightface. Synonyms of Lightface

- of these sets). This relationship between lightface sets and their indices is used to extend the lightface Borel hierarchy into the transfinite, via recursive...
- countable intersection of open sets. These sets are called Gδ sets. The lightface Borel hierarchy (also called the effective Borel hierarchypp.163--164)...
- _{n}^{0}} for natural numbers n (including 0). The Gr**** letters here are lightface symbols, which indicates that the formulas do not contain set parameters...
- classifies sets by the formulas that can be used to define them; it is the lightface version of the projective hierarchy. The notation Σ 0 1 = Π 0 1 = Δ 0...
- ∩ L {\displaystyle {\mathcal {P}}(\omega )\cap L} consists of all the lightface Δ n 1 {\displaystyle \Delta _{n}^{1}} subsets of ω {\displaystyle \omega...
- In descriptive set theory, a lightface analytic game is a game whose payoff set A is a Σ 1 1 {\displaystyle \Sigma _{1}^{1}} subset of Baire space; that...
- Pointclasses v t e Lightface Boldface Σ0 0 = Π0 0 = Δ0 0 (sometimes the same as Δ0 1) Σ0 0 = Π0 0 = Δ0 0 (if defined) Δ0 1 = recursive Δ0 1 = clopen Σ0...
- relativized analytical hierarchy on subsets of Baire space (denoted by lightface letters Σ {\displaystyle \Sigma } and Π {\displaystyle \Pi } ) and the...
- is between set theory and recursion theory. It includes the study of lightface pointclasses, and is closely related to hyperarithmetical theory. In many...
- com****bility theory. Another family of basis theorems concern nonempty lightface analytic sets (that is, Σ 1 1 {\displaystyle \Sigma _{1}^{1}} in the analytical...