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I'm studying certain polynomials of 2 complex variables, say x and y. These polynomials have roots at the non-negative integers, that is both $x$ and $y$ have to be

$x,y \in \mathbb{N}$

simultaneously with the restriction that

$x+y \leq A$

for some non-negative integer A. I'd like to know the basis for these polynomials of minimal total degree (sum of degrees in $x$ and $y$), up to overal constants. I think this basis is:

$\left(x \atop n\right)\left(y \atop A+1-n\right)$

for integer $n$ with $0 \leq n \leq A+1$. The brackets are falling factorials:

$\left(x \atop n\right) = x (x-1)....(x-n-1)$

with $\left(x \atop 0\right)\equiv 1$

At the moment I have only a proof-by-lack-of-imagination argument that this is the full set. Of course, I'd also like to know how to generalize to multiple complex variables :)

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  • $\begingroup$ What do you mean exactly by "total degree" of a finite set of polynomials? The maximum of their (total) degrees, the sum of their degrees... $\endgroup$ Aug 30, 2013 at 9:53
  • $\begingroup$ the sum of $i$ and $j$ in term of the type $x^i y^j$ $\endgroup$
    – twistorial
    Aug 30, 2013 at 10:00
  • $\begingroup$ No, I mean, you want to compare different sets of generators; how should we define the "total degree" of such a set? I know what is the "total degree" of a polynomial, but here you're asking how to compare sets of them if I am understanding the question correctly. $\endgroup$ Aug 30, 2013 at 16:26
  • $\begingroup$ The question is about the "set of these (polynomials of minimal total degree)", not "(set of these polynomials) of minimal total degree". $\endgroup$
    – user39445
    Sep 2, 2013 at 9:09
  • $\begingroup$ edited for clarification... apologies for not thinking like a mathematician :) $\endgroup$
    – twistorial
    Sep 2, 2013 at 9:25

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