Eliza Wajch

6 Questions 22 Answers 0 Followers

Questions related from Eliza Wajch

Is there a model for ZF in which a topological group can fail to be completely regular?

I know that It holds true in ZFC (even in ZF+DC) that every topological group is completely regular. It is also known to me that, in some models for ZF, a topology induced by a uniformity can be...

06 June 2016 8,890 3 View

Let M be a model for ZF such that Cut(n) holds in M for each positive integer n. Must Cut(fin) hold in M?

Let me recall that, for a positive integer n, Cut(n) is the statement that, for each sequence of n-element sets, the union of all sets of this sequence is at most countable. Cut(fin) is the...

06 June 2016 7,099 11 View

Is there a model for ZF in which \omega_1 is regular but CC(R) fails?

H. Herrlich and K. Keremedis wrote in their article "Remarks on the space $\aleph_1$ in ZF" (Topol. Appl. 158 (2011)) that CC($\mathbb{R}$) implies that the first uncountable cardinal number is...

10 October 2015 3,335 2 View

Are all models from the appendix of Herrlich's book really ZF-models?

In the appendix of Herrlich's book ``Axiom of Choice'', there are diagrams illustrating properties of several models for ZF^{-}. In the introduction to the appendix of this book, it is written...

08 August 2015 3,472 3 View

Do you know enough about logics in which modus ponens fails?

In the book "An Introduction to Non-Classical Logic" by G. Priest, logics in which modus ponens fails are mentioned. I think that they can be relevant to the text "Generalized Modus Ponens and...

03 March 2015 9,402 5 View

How strongly does Hilbert projection theorem depend on CC?

In the standard proof of Hilbert projection theorem the axiom of countable choice (denoted by CC) is used. I wonder whether there is a model of ZF+ the negation of CC in which Hilbert projection...

01 January 1970 5,626 3 View