2012 seminar talk: On Sigma-definability of structures over the reals

Talk held by Andrey Morozov (Novosibirsk State University, Russia) at the KGRC seminar on 2012-06-28.


We give a brief survey of the results on structures $\Sigma$-definable over $HF(R)$ and present some further results on the number of non-$\Sigma$-isomorphic presentations of the ordered field R of reals and of its ordering. In particular, we will discuss a question, whether is it possible to use R to 'improve' itself by creating its new classically isomorphic $\Sigma$-copy.

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Kurt Gödel Research Center for Mathematical Logic. Währinger Straße 25, 1090 Wien, Austria. Phone +43-1-4277-50501. Last updated: 2010-12-16, 04:37.