The freeness of ideal subarrangements of Weyl arrangements
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چکیده
منابع مشابه
The freeness of ideal subarrangements of Weyl arrangements
A Weyl arrangement is the arrangement defined by the root system of a finite Weyl group. When a set of positive roots is an ideal in the root poset, we call the corresponding arrangement an ideal subarrangement. Our main theorem asserts that any ideal subarrangement is a free arrangement and that its exponents are given by the dual partition of the height distribution, which was conjectured by ...
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In arrangements of pseudocircles (i.e., Jordan curves) the weight of a vertex (i.e., an intersection point) is the number of pseudocircles that contain the vertex in its interior. We show that in complete arrangements (in which each two pseudocircles intersect) 2n−1 vertices of weight 0 force an α-subarrangement, a certain arrangement of three pseudocircles. Similarly, 4n−5 vertices of weight 0...
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متن کاملThe integer cohomology of toric Weyl arrangements
A toric arrangement is a finite set of hypersurfaces in a complex torus, every hypersurface being the kernel of a character. In the present paper we prove that if T W̃ is the toric arrangement defined by the cocharacters lattice of a Weyl group W̃ , then the integer cohomology of its complement is torsion free.
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ژورنال
عنوان ژورنال: Journal of the European Mathematical Society
سال: 2016
ISSN: 1435-9855
DOI: 10.4171/jems/615