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Compactness theorem

In mathematical logic, the compactness theorem states that a set of first-order sentences has a model if and only if every finite subset of it has a model. This theorem is an important tool in model theory, as it provides a useful (but generally not effective) method for constructing models of any set of sentences that is finitely consistent.

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Field
Mathematical logic
Generalizations
Gödel's completeness theorem
Statement
A set of first-order sentences has a model if and only if every finite subset of it has a model.

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Compactness theorem

Nodes55
Edges54
Triples43
Avg. degree1.96
Density0.036364
Components1

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Compactness theorem

Top relations

related to Robinson's principle · 9
Compactness theorem → Abraham Robinson, Because, If, Let, Robinson's, The, Then, Therefore, This
related to Upward Löwenheim–Skolem theorem · 9
Compactness theorem → Add, But, Peano, Since, Skolem, So, Then, To, Upward Löwenheim
related to Proofs · 6
Compactness theorem → Boolean, Gödel, Gödel's, In, One, Since
related to Non-standard analysis · 5
Compactness theorem → By, Clearly, Consider, Sigma, To
see also · 5
Compactness theorem → Barwise, Boolean, Existence, Fundamental, Skolem
related to External links · 2
Compactness theorem → Internet Encyclopedia, Philosophy
related to history · 2
Compactness theorem → Anatoly Maltsev, Kurt Gödel
Field · 1
Compactness theorem → Mathematical logic
Generalizations · 1
Compactness theorem → Gödel's completeness theorem
Statement · 1
Compactness theorem → A set of first-order sentences has a model if and only if every finite subset of it has a model.

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Important terminology

displaystyle theorem compactness model finite every sentences theory first-order field sigma logic set characteristic satisfiable isbn varphi one subset numbers

Entity relationships Subject–Predicate–Object triples

SubjectPredicateObjectConfidenceSrc
Compactness theoremFieldMathematical logic1.00infobox
Compactness theoremGeneralizationsGödel's completeness theorem1.00infobox
Compactness theoremStatementA set of first-order sentences has a model if and only if every finite subset of it has a model.1.00infobox
Compactness theoremis aconstruction of nonstandard models of the real numbers0.90text
Compactness theoremhas applicationThe0.60section
Compactness theoremrelated to External linksInternet Encyclopedia0.60section
Compactness theoremrelated to External linksPhilosophy0.60section
Compactness theoremrelated to historyKurt Gödel0.60section
Compactness theoremrelated to historyAnatoly Maltsev0.60section
Compactness theoremrelated to Non-standard analysisTo0.60section
Compactness theoremrelated to Non-standard analysisSigma0.60section
Compactness theoremrelated to Non-standard analysisConsider0.60section

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