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COMBINATORICS
1998
84views more  COMBINATORICS 1998»
14 years 9 months ago
Multimatroids II. Orthogonality, minors and connectivity
A multimatroid is a combinatorial structure that encompasses matroids, delta-matroids and isotropic systems. This structure has been introduced to unify a theorem of Edmonds on th...
André Bouchet
COMBINATORICS
1998
88views more  COMBINATORICS 1998»
14 years 9 months ago
Multi-statistic enumeration of two-stack sortable permutations
Using Zeilberger’s factorization of two-stack-sortable permutations, we write a functional equation — of a strange sort — that defines their generating function according t...
Mireille Bousquet-Mélou
COMBINATORICS
1998
42views more  COMBINATORICS 1998»
14 years 9 months ago
On Noncrossing and Nonnesting Partitions for Classical Reflection Groups
The number of noncrossing partitions of {1, 2, . . . , n} with fixed block sizes has a simple closed form, given by Kreweras, and coincides with the corresponding number for nonne...
Christos A. Athanasiadis
COMBINATORICS
1998
60views more  COMBINATORICS 1998»
14 years 9 months ago
Finite Vector Spaces and Certain Lattices
The Galois number Gn(q) is defined to be the number of subspaces of the n-dimensional vector space over the finite field GF(q). When q is prime, we prove that Gn(q) is equal to...
Thomas W. Cusick
COMBINATORICS
1998
130views more  COMBINATORICS 1998»
14 years 9 months ago
Codes and Projective Multisets
The paper gives a matrix-free presentation of the correspondence between full-length linear codes and projective multisets. It generalizes the BrouwerVan Eupen construction that t...
Stefan M. Dodunekov, Juriaan Simonis