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Difference between revisions of "Robinson test"

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The following necessary and sufficient criterion for an [[Elementary theory|elementary theory]] <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/r/r110/r110130/r1101301.png" /> to be model complete (cf. [[Model theory|Model theory]]): for every two models <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/r/r110/r110130/r1101302.png" /> and <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/r/r110/r110130/r1101303.png" /> of <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/r/r110/r110130/r1101304.png" /> such that <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/r/r110/r110130/r1101305.png" /> is a substructure of <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/r/r110/r110130/r1101306.png" /> (cf. [[Structure(2)|Structure]]), it follows that <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/r/r110/r110130/r1101307.png" /> is [[Existentially closed|existentially closed]] in <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/r/r110/r110130/r1101308.png" />.
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The following necessary and sufficient criterion for an [[elementary theory]] $T$ to be model complete (cf. [[Model theory]]): for every two models $A$ and $B$ of $T$ such that $A$ is a substructure of $B$ (cf. [[Structure(2)|Structure]]), it follows that $A$ is [[existentially closed]] in $B$.
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Latest revision as of 19:56, 9 December 2016

The following necessary and sufficient criterion for an elementary theory $T$ to be model complete (cf. Model theory): for every two models $A$ and $B$ of $T$ such that $A$ is a substructure of $B$ (cf. Structure), it follows that $A$ is existentially closed in $B$.

How to Cite This Entry:
Robinson test. Encyclopedia of Mathematics. URL: http://encyclopediaofmath.org/index.php?title=Robinson_test&oldid=39937
This article was adapted from an original article by F.-V. Kuhlmann (originator), which appeared in Encyclopedia of Mathematics - ISBN 1402006098. See original article