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This article lists mathematical properties and laws of sets, involving the set-theoretic operations of union, intersection, and complementation and the relations of set equality and set inclusion. It also provides systematic procedures for evaluating expressions, and performing calculations, involving these operations and relations.
Kurt Gödel proved in 1940 that the negation of the continuum hypothesis, i.e., the existence of a set with intermediate cardinality, could not be proved in standard set theory. [2] The second half of the independence of the continuum hypothesis – i.e., unprovability of the nonexistence of an intermediate-sized set – was proved in 1963 by ...
In set theory, is also used to indicate 'not in the set of': is the set of all members of U that are not members of A. Regardless how it is notated or symbolized , the negation ¬ P {\displaystyle \neg P} can be read as "it is not the case that P ", "not that P ", or usually more simply as "not P ".
In non-well-founded set theories, the foundation axiom of ZFC is replaced by axioms implying its negation. The study of non-well-founded sets was initiated by Dmitry Mirimanoff in a series of papers between 1917 and 1920, in which he formulated the distinction between well-founded and non-well-founded sets; he did not regard well-foundedness as ...
The concept of a stable model, or answer set, is used to define a declarative semantics for logic programs with negation as failure.This is one of several standard approaches to the meaning of negation in logic programming, along with program completion and the well-founded semantics.
In mathematics, a set is inhabited if there exists an element . In classical mathematics, the property of being inhabited is equivalent to being non- empty . However, this equivalence is not valid in constructive or intuitionistic logic , and so this separate terminology is mostly used in the set theory of constructive mathematics .
A set of polygons in an Euler diagram This set equals the one depicted above since both have the very same elements.. In mathematics, a set is a collection of different [1] things; [2] [3] [4] these things are called elements or members of the set and are typically mathematical objects of any kind: numbers, symbols, points in space, lines, other geometrical shapes, variables, or even other ...
If satisfiability were also a semi-decidable problem, then the problem of the existence of counter-models would be too (a formula has counter-models iff its negation is satisfiable). So the problem of logical validity would be decidable, which contradicts the Church–Turing theorem, a result stating the negative answer for the ...