Tuesday, November 7, 2017
3:00 pm
Building 15, Room 131 – Building 15

Logic Seminar

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.

Contact Mathematics Department mathinfo@caltech.edu at 626-395-4335
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