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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

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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 centralsimplealgebra) 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 codimension 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 
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Robotics, Cryptography, and Genetics applications of Grothendieck's work?
I do not think that MO is wellsuited to speculation about what might or might not have been in the mind of a reporter for the New York Times. 
Nov 19 
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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 selfpromotion) to point to the far more ambitious blog post here: thebigquestions.com/2014/11/17/thegeneralist 
Nov 17 
answered  Probability spaces involved in using Bayesian Inference 