943 reputation
816
bio website a.b.c.d
location Paris, France
age 55
visits member for 3 years, 6 months
seen Sep 12 at 11:54

Not much to say.


Jan
30
comment Proof concerning Latin squares
You are welcome. Consider reading a book about problem solving. The one which was fashionable in my time was Polya's, but there a lot of resources available on the web and in libraries.
Apr
14
comment Orthogonal Latin Square 6*6
See my answer for a link on the original paper. A physical copy of the journal of the French "Association for l'Avancement des Sciences" is not so easy to find outside France (where most University libraries have it).
May
25
comment Non-associative, non-commutative binary operation with a identity
what's the point of adding y if it is zero! Are you sure this was what you meant?
May
25
comment When $G'$/$G''$ and $G''$ both are cyclic groups
@Basil R: you should edit your title and question.
May
24
comment A question about integral quadratic forms
The left part of your equation is what mathematicians call a (integral) quadratic form. There is a lot of results about the integers n they can represent or not.
May
24
comment Prove that if $(ab)^i = a^ib^i \forall a,b\in G$ for three consecutive integers $i$ then G is abelian
thanks a lot for these references. We speak of Exponent semigroup, Levi semigroup, etc. What is the operation on these sets?
May
23
comment How to split an integral exactly in two parts
@Byron: thanks for this careful explanation with references.
May
20
comment Probability of a point taken from a certain normal distribution will be greater than a point taken from another?
Just to be sure: do you consider the two draws to be strictly independent, i.e. the mechanism simulated by the second draw is not modified or influenced by the value of the first? If this is the case, the problem can be rephrased very simply, while perhaps not realistic. Also note that there is Cross-Validated, the SE site for statistical Q&A.
May
20
comment Logic Puzzle of the age of three sons
@Amy : see my answer to R. Israel. No this is not a standard, just a possible thought process of the problem's author. As these problems are supposed to make youngsters manipulate properties of integers, this made-up rule is a way to introduce the composite/prime distinction in the problem.
May
20
comment Logic Puzzle of the age of three sons
@Robert Israel: I agree with you, and I should not have presented my interpretation as if I believed that buildings are somehow figurate numbers. Just a hint or a trick toward a possible solution. As user6312 said, we are not doing mathematics here. We are just trying to outguess/reverse engineer a very vague and inconsistent fantasy world which is more or less shared among variants of these kinds of problem. This riddle is only a support for successive hypothesis and manipulation of integers, not a scientific slice of reality.
May
19
comment Logic Puzzle of the age of three sons
@svenkatr : You are right that this way was not listed. But if there is (one) older son, 1,6,6;13 is not possible.
May
19
comment Logic Puzzle of the age of three sons
@El'endia : a building has several floors with the same number of windows at each floor, so the number must be composite and not prime.
May
19
comment A Question about p-primary Group
@Arturo: I asked only to better understand etiquette on math.SE.
May
19
comment Why are there only a finite number of sporadic simple groups?
@Joseph : John is referring to Claude Chevalley's article in the Tohoku Journal : Sur certains groupes simples, Tohoku Math. J. (2) Volume 7, Number 1-2 (1955), pp14-66. You can find it on a library or Project Euclid.
May
19
comment A Question about p-primary Group
@Arturo : You seem to think that the original wording of the question should stay and that it is better to have the clarification in the answer. Am I correct?
May
19
comment What structure is this?
In your description, r(x) and r(x,y) do not depend on x, but only on the coefficients of f,g,h. Is it a typo or do you really mean that r(x) and r(x,y) are constants and not power series?
May
15
comment Application of Galois theory
@Qiaochu : I am interested to know if you agree with the version.
May
15
comment Application of Galois theory
@iyengar: Your question seems motivated by the reading of a textbook or an example presented as motivation for Galois Theory. Perhaps you can give us more context as well?
May
15
comment Application of Galois theory
@Qiaochu : right, it was developed around that particular problem but is not restricted to it. I will change my wording.
Apr
25
comment what is the difference between field and group in algebra
@Mariano: you are right the confusion stems from the meaning of "parent" in french which is more inclusive than in modern english. I will edit my text again, thanks for your remark. But I maintain that there is a stronger and genetic link between groups and rings than between (to take your own example), topological spaces and groups, even if in my opinion, the latter link is quite close too.