# André Nicolas

 9h comment Why don't we consider non-units as quadratic residues?If we were more inclusive, too many theorems, proofs would have to say "quadratic residue relatively prime to $n$" instead of "quadratic residue." Also, for many years the focus was almost entirely on prime $n$. 10h comment About restriction of linear mapYou are welcome. That's what the site is for. 11h comment How to represent a sequence of odd numbers given specific critereaThere is a substantial body of related results. There are various interpretations of your question. Here are some questions that will help any answerer. (i) Does order matter? Is $1,3,5$ different from $3,5,1$? (ii) Are we allowed things like $3,3,3$? 13h comment Is there a procedure to solve Diophantine Equations?@mixedmath: The general Fermat equation is an example of an exponential Diophantine equation. The Matiyasevich result is for ordinary Diophantine equations, no variables in the exponent. Undecidability of exponential diophantine equations was proved a number of years before Matiyasevich's result, by Davis-Putnam-Robinson. 13h comment Is there a procedure to solve Diophantine Equations?There is stuff in Logical Number Theory (Smorynski). Lots of other sources. It is essentially an application of the Hasse Principle. 13h revised What would be the expected number of targets which didn't get hit by any of the shooters?added 77 characters in body 13h comment What would be the expected number of targets which didn't get hit by any of the shooters?Distinguishable or not makes no difference here. 13h comment What would be the expected number of targets which didn't get hit by any of the shooters?There are quite a few important examples where a linearity argument gives the answer. For example, suppose we pick $k$ balls without replacement from a collection of $b$ blue and $r$ red. The indicator random variable approach used above quickly tells us the expected number of red. The combinatorial approach is a bit more messy. And I know of examples where the distribution is basically not accessible, but indicator rv works quickly. 13h revised What would be the expected number of targets which didn't get hit by any of the shooters?added 384 characters in body 13h answered What would be the expected number of targets which didn't get hit by any of the shooters? 13h answered Is there a procedure to solve Diophantine Equations? 13h revised About restriction of linear mapadded 402 characters in body 14h comment About restriction of linear map@mathscrazy: I had just added it. 14h answered About restriction of linear map 14h revised Questions about $\mathrm{Aut}(\mathbb{Q} (\sqrt{2}, \sqrt{3})/\mathbb{Q})$added 45 characters in body 14h revised Beginner Probability Questionadded 809 characters in body 14h answered Beginner Probability Question 14h answered Questions about $\mathrm{Aut}(\mathbb{Q} (\sqrt{2}, \sqrt{3})/\mathbb{Q})$ 14h comment Is game theory a part of math?Useful mathematics is still mathematics. 15h comment A quick Poisson distribution problem@DaleM: Thank you! I am not changing the remark at the end, since people reading the answer have access to your valuable reference.