Potential isomorphism

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In mathematical logic and in particular in model theory, a potential isomorphism is a collection of finite partial isomorphisms between two models which satisfies certain closure conditions. Existence of a partial isomorphism entails elementary equivalence, however the converse is not generally true, but it holds for ω-saturated models.

Mathematical logic is a subfield of mathematics exploring the applications of formal logic to mathematics. It bears close connections to metamathematics, the foundations of mathematics, and theoretical computer science. The unifying themes in mathematical logic include the study of the expressive power of formal systems and the deductive power of formal proof systems.

In mathematics, model theory is the study of classes of mathematical structures from the perspective of mathematical logic. The objects of study are models of theories in a formal language. A set of sentences in a formal language is one of the components that form a theory. A model of a theory is a structure that satisfies the sentences of that theory.

In mathematical logic, and particularly in its subfield model theory, a saturated modelM is one which realizes as many complete types as may be "reasonably expected" given its size. For example, an ultrapower model of the hyperreals is -saturated, meaning that every descending nested sequence of internal sets has a nonempty intersection, see Goldblatt (1998).

Definition

A potential isomorphism between two models M and N is a non-empty collection F of finite partial isomorphisms between M and N which satisfy the following two properties:

A notion of Ehrenfeucht-Fraïssé game is an exact characterisation of elementary equivalence and potential isomorphism can be seen as an approximation of it. Another notion that is similar to potential isomorphism is that of local isomorphism.

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References

Howard Jerome Keisler American mathematician

Howard Jerome Keisler is an American mathematician, currently professor emeritus at University of Wisconsin–Madison. His research has included model theory and non-standard analysis.

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Elsevier is a Dutch information and analytics company and one of the world's major providers of scientific, technical, and medical information. It was established in 1880 as a publishing company. It is a part of the RELX Group, known until 2015 as Reed Elsevier. Its products include journals such as The Lancet and Cell, the ScienceDirect collection of electronic journals, the Trends and Current Opinion series of journals, the online citation database Scopus, and the ClinicalKey solution for clinicians. Elsevier's products and services include the entire academic research lifecycle, including software and data-management, instruction and assessment tools.

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