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