François G. Dorais
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 May 27 comment A quick question about categoricity in model theory Categorical theory is often used to mean a theory that is $\kappa$-categorical for every infinite cardinal $\kappa$. Mar 28 awarded Nice Answer Feb 6 awarded Nice Answer Jan 30 awarded Nice Answer Dec 19 comment How can I prove that the additive group of rationals is not isomorphic to a direct product of two nontrivial groups? Here is an approach: show that any two nontrivial subgroups of $\mathbb{Q}$ have nontrivial intersection. Seems very localized though, I would like to see a more general argument. Oct 28 comment Properties of computable numbers There is no effective enumeration of all computable numbers. However, there are effective enumerations of the Turing machines, but not all Turing machines compute real numbers. How should we think of those machines that don't compute real numbers? Sep 5 revised What's the difference between these two Venn diagrams? spelling in title Sep 5 suggested approved edit on What's the difference between these two Venn diagrams? Sep 1 revised Descriptions of sets and the Axiom of Choice correction Aug 31 comment Descriptions of sets and the Axiom of Choice Well, $OD$ is transitive whenever $V = OD$ since $V$ is always transitive, so $V = OD$ and $V = HOD$ mean exactly the same thing. Aug 31 answered Descriptions of sets and the Axiom of Choice Aug 27 answered Formalizing metamathematics Aug 23 comment Can one avoid AC in the proof that in Noetherian rings there is a maximal element for each set? Good point, Arturo. Note that Hodges separates the three definitions in the paper cited above. Aug 22 comment Karatsuba vs. Schönhage-Strassen for multiplication of polynomials This answer assumes that the coefficients of the polynomials are integers. I thought that was part of the question, but I now see that it wasn't... Aug 22 revised Karatsuba vs. Schönhage-Strassen for multiplication of polynomials small correction Aug 22 comment Can one avoid AC in the proof that in Noetherian rings there is a maximal element for each set? Yes, see W. Hodges, Six impossible rings, J. Algebra 31 (1974), 218-244. Aug 22 answered Can one avoid AC in the proof that in Noetherian rings there is a maximal element for each set? Aug 22 revised Karatsuba vs. Schönhage-Strassen for multiplication of polynomials fixed typo Aug 22 answered Karatsuba vs. Schönhage-Strassen for multiplication of polynomials Aug 9 comment For every infinite $S$, $|S|=|S\times S|$ implies the Axiom of choice @Asaf: I'm not used to the quality standards of this site, if you (or anyone else) want to flesh out my answer, please go right ahead...