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oligomorphic permutation group (Definition)

A permutation group acting on a countably infinite set is called oligomorphic, if it has finitely many orbits of $ n$-tuples, for all $ n \geq 1$.

Ryll-Nardzewski, Engeler, and Svenonius proved that a countably infinite first-order structure has an oligomorphic automorphism group if and only if the structure is $ \omega$-categorical.



"oligomorphic permutation group" is owned by amador.
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See Also: countably categorical structures

Also defines:  oligomorphic automorphism group
Keywords:  Infinite Permutation Groups
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Cross-references: structure, orbits, countably infinite, permutation group
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This is version 3 of oligomorphic permutation group, born on 2005-05-12, modified 2005-05-12.
Object id is 7044, canonical name is OligomorphicPermutationGroup.
Accessed 1388 times total.

Classification:
AMS MSC03C35 (Mathematical logic and foundations :: Model theory :: Categoricity and completeness of theories)

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