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Logic Seminar

Wednesday, November 16, 2022
11:00am to 12:00pm
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Polish modules over subrings of Q
Dexuan Hu, Department of Mathematics, Cornell University,

Please note that the time is PST

We give a method of producing a Polish module over an arbitrary subring of Q from an ideal of subsets of N and a sequence in N. The method allows us to construct two Polish Q-vector spaces, U and V, such that
– both U and V embed into R, but
– U does not embed into V and V does not embed into U,
where by an embedding we understand a continuous Q-linear injection. This construction answers a question of Frisch and Shinko. In fact, our method produces a large number of incomparable with respect to embeddings Polish Q-vector spaces.
This is joint work with Slawomir Solecki.

For more information, please contact Math Dept. by phone at 626-395-4335 or by email at A. Kechris at [email protected].