set-theoretical
41Foundations of mathematics — is a term sometimes used for certain fields of mathematics, such as mathematical logic, axiomatic set theory, proof theory, model theory, and recursion theory. The search for foundations of mathematics is also a central question of the philosophy …
42Basis (universal algebra) — Definitions The basis (or reference frame) of a (universal) algebra is a function b that takes some algebra elements as values b(i) and satisfies either one of the following two equivalent conditions. Here, the set of all b(i) is called basis set …
43Fibred category — Fibred categories are abstract entities in mathematics used to provide a general framework for descent theory. They formalise the various situations in geometry and algebra in which inverse images (or pull backs) of objects such as vector bundles …
44Natural number — Natural numbers can be used for counting (one apple, two apples, three apples, ...) from top to bottom. In mathematics, the natural numbers are the ordinary whole numbers used for counting ( there are 6 coins on the table ) and ordering ( this is …
45New Foundations — In mathematical logic, New Foundations (NF) is an axiomatic set theory, conceived by Willard Van Orman Quine as a simplification of the theory of types of Principia Mathematica. Quine first proposed NF in a 1937 article titled New Foundations for …
46András Hajnal — (* 13. Mai 1931 in Ungarn) ist ein ungarischer Mathematiker. Hajnal studierte Mathematik an der Loránd Eötvös Universität in Budapest, wo er 1953 sein Diplom erhielt. Er wurde 1957 bei László Kalmár promoviert (Kandidatentitel) und 1962… …
47Forcing (mathematics) — For the use of forcing in recursion theory, see Forcing (recursion theory). In the mathematical discipline of set theory, forcing is a technique invented by Paul Cohen for proving consistency and independence results. It was first used, in 1963,… …
48Controversy over Cantor's theory — In mathematical logic, the theory of infinite sets was first developed by Georg Cantor. Although this work has found wide acceptance in the mathematics community, it has been criticized in several areas by mathematicians and philosophers. Cantor… …
49Borel determinacy theorem — In descriptive set theory, the Borel determinacy theorem shows that any Gale Stewart game whose winning set is a Borel set is determined, meaning that one of the two players will have a winning strategy for the game. It was proved by Donald A.… …
50Category of sets — In mathematics, the category of sets, denoted as Set, is the category whose objects are all sets and whose morphisms are all functions. It is the most basic and the most commonly used category in mathematics.Properties of the category of setsThe… …
