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Caltech

Logic Seminar

Tuesday, November 7, 2017
3:00pm to 4:00pm
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Building 15, Room 131
Strange structures from computable model theory
Howard Becker, visiting Caltech,

Let L be a countable language, let I be an isomorphism-type of countable L-structures and let a be an oracle. We say that I is "a-strange" if it contains a recursive-in-a structure and its Scott rank is exactly omega_1^a. Such structures exist but there are no known natural examples. Theorem(AD): If C is a collection of aleph_1 isomorphism-types of countable structures, then for a Turing cone of a's, no member of C is a-strange.

For more information, please contact Mathematics Department by phone at 626-395-4335 or by email at [email protected].