Sign-Graded Posets, Unimodality of W-Polynomials and the Charney-Davis Conjecture
نویسنده
چکیده
We generalize the notion of graded posets to what we call sign-graded (labeled) posets. We prove that the W -polynomial of a sign-graded poset is symmetric and unimodal. This extends a recent result of Reiner and Welker who proved it for graded posets by associating a simplicial polytopal sphere to each graded poset. By proving that the W -polynomials of sign-graded posets has the right sign at −1, we are able to prove the Charney-Davis Conjecture for these spheres (whenever they are flag).
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ورودعنوان ژورنال:
- Electr. J. Comb.
دوره 11 شماره
صفحات -
تاریخ انتشار 2004