Polynomials with the half-plane property and matroid theory
نویسندگان
چکیده
منابع مشابه
On the half-plane property and the Tutte group of a matroid
A matroid has the weak half-plane property (WHPP) if there exists a stable polynomial with support equal to the set of bases of the matroid. If the polynomial can be chosen with all nonzero coefficients equal to one then the matroid has the half-plane property (HPP). We describe a systematic method that allows us to reduce the WHPP to the HPP for large families of matroids. This method makes us...
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For example, x1 + · · · + xd ∈ Ud (C). This follows from the fact that the upper half plane is a cone, so if σ1, . . . , σd are in the upper half plane then so is their sum. Another example is x1x2 − 1. If σ1 and σ2 are in the upper half plane then σ1σ2 ∈ C \ (0,∞), so σ1σ2 − 1 is not zero. U1 (C) is easily described. It is all polynomials in one variable whose roots are either real, or lie in ...
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ژورنال
عنوان ژورنال: Advances in Mathematics
سال: 2007
ISSN: 0001-8708
DOI: 10.1016/j.aim.2007.05.011