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4h
comment How can i be distinguished from -i?
@JoelDavidHamkins: Re Shapiro's article, I have a great deal of difficulty seeing the point. If I have a theory with the single axiom $x=x$, then all elements of all models are indistinguishable. If I have a much richer theory, things become distinguishable. It turns out that the theory of the real numbers is not strong enough to distinguish $i$ from $-i$ but the theory of the complex numbers is. This makes the $i/-i$ distinction no different from any other distinction --- every pair of things is indistinguishable given a sufficiently weak theory. Have I missed something?
8h
comment Model of function of 2 random variables
This is pretty much incomprehensible, I think. For starters, what does $f'$ mean?
Dec
15
comment Maths to take a user chosen number to a predictable number
I really really want to know who upvoted this one.
Dec
15
comment Maths to take a user chosen number to a predictable number
Darn. Emil changed the tag (from central-simple-algebra) just as I was about to make a suggestion involving computation of Brauer groups.
Dec
15
awarded  Necromancer
Dec
15
comment Why do we teach calculus students the derivative as a limit?
@quid: Well, of course. The Greeks were very primitive and had not yet discovered the letter $h$.
Dec
14
answered Why do we teach calculus students the derivative as a limit?
Dec
9
comment Upper bound on number of cells created by varieties of co-dimension 1
Are these polynomials supposed to take their values in an ordered field? Otherwise what's a "region"?
Dec
5
revised Irreducibility after substitution
added 205 characters in body
Dec
5
revised Irreducibility after substitution
added 438 characters in body
Dec
5
revised Irreducibility after substitution
added 438 characters in body
Dec
5
revised Irreducibility after substitution
added 333 characters in body
Dec
5
revised Irreducibility after substitution
added 65 characters in body
Dec
5
answered Irreducibility after substitution
Dec
3
awarded  Electorate
Nov
30
awarded  Nice Answer
Nov
23
comment Grothendieck -sad news
I very much second the recommendations of the Grothendieck/Serre correspondence and Recoltes et Semailles.
Nov
19
comment Robotics, Cryptography, and Genetics applications of Grothendieck's work?
I do not think that MO is well-suited to speculation about what might or might not have been in the mind of a reporter for the New York Times.
Nov
19
comment Grothendieck -sad news
In view of the positive response to David Roberts's comment pointing to my first blog post, I am moved (though with some trepidation about self-promotion) to point to the far more ambitious blog post here: thebigquestions.com/2014/11/17/the-generalist
Nov
17
answered Probability spaces involved in using Bayesian Inference