نتایج جستجو برای: shelling
تعداد نتایج: 400 فیلتر نتایج به سال:
We prove that if a simplicial complex ∆ is shellable, then the intersection lattice L∆ for the corresponding diagonal arrangement A∆ is homotopy equivalent to a wedge of spheres. Furthermore, we describe precisely the spheres in the wedge, based on the data of shelling. Also, we give some examples of diagonal arrangements A where the complement MA is K(π, 1), coming from rank 3 matroids.
Materials Physics & Applications Division: Los Alamos National Laboratory, Los Ala [email protected] Department of Physics, University of Texas Department of Physics, Fordham University Defense Systems and Analysis Division: Alamos National Laboratory, Los Alamos, N Chemistry Division: Physical Chemistry & A Laboratory, Los Alamos, New Mexico 87545 Theoretical Division: Physics of Condensed Nationa...
Several combinatorial problems of (quasi)crystallography are reviewed with special emphasis on a unified approach, valid for both crystals and quasicrystals. In particular, we consider planar sublattices, similarity sublattices, coincidence sublattices and their module counterparts. The corresponding counting functions are encapsulated in Dirichlet series generating functions, with worked out r...
We introduce a notion of lexicographic shellability for pure, balanced boolean cell complexes, modelled after the CL-shellability criterion of Björner and Wachs (Adv. in Math. 43 (1982), 87–100) for posets and its generalization by Kozlov (Ann. of Comp. 1(1) (1997), 67–90) called CC-shellability. We give a lexicographic shelling for the quotient of the order complex of a Boolean algebra of rank...
The broken circuit complex plays a fundamental role for the shellability and homology of matroids, geometric lattices and linear hyperplane arrangements. Here we introduce and study the β-system of a matroid, βnbc(M), whose cardinality is Crapo’s β-invariant. In studying the shellability and homology of base-pointed matroids, geometric semilattices and affine hyperplane arrangements, we find th...
Peanut quality parameters were analyzed across four irrigation levels during the 2002 through 2007 crop years. The peanut quality parameters consisted of total sound mature kernels and sound splits (farmer stock grade), shelling outturn by commercial edible size, accept and reject kernels by commercial edible size, seed germination, and aflatoxin. The four irrigation levels consisted of a full ...
Given a real finite hyperplane arrangement A and a point p not on any of the hyperplanes, we define an arrangement vo(A, p), called the valid order arrangement, whose regions correspond to the different orders in which a line through p can cross the hyperplanes in A. If A is the set of affine spans of the facets of a convex polytope P and p lies in the interior of P, then the valid orderings wi...
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