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Permutation polytopes and indecomposable elements in permutation groups
 J. Combin. Theory Ser. A
"... Abstract. Each group G of n × n permutation matrices has a corresponding permutation polytope, P(G): = conv(G) ⊂ R n×n. We relate the structure of P(G) to the transitivity of G. In particular, we show that if G has t nontrivial orbits, then min{2t, ⌊n/2⌋} is a sharp upper bound on the diameter of t ..."
Indecomposable coverings
 In The China–Japan Joint Conference on Discrete Geometry, Combinatorics and Graph Theory (CJCDGCGT 2005), Lecture Notes in Computer Science
, 2007
"... Dedicated to the memory of László Fejes Tóth Abstract. We prove that for every k> 1, there exist kfold coverings of the plane (1) with strips, (2) with axisparallel rectangles, and (3) with homothets of any fixed concave quadrilateral, that cannot be decomposed into two coverings. We also const ..."
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Cited by 8 (0 self)
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construct, for every k> 1, a set of points P and a family of disks D in the plane, each containing at least k elements of P, such that no matter how we color the points of P with two colors, there exists a disk D ∈ D, all of whose points are of the same color. 1 Multiple arrangements: background
On the Number of Indecomposable Block Designs
, 1996
"... A t(v; k; ) design D is a system (multiset) of kelement subsets (called blocks) of a velement set V such that every telement subset of V occurs exactly times in the blocks of D. A t(v; k; ) design D is called indecomposable (or elementary) if and only if there is no subsystem which is a ! ..."
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A t(v; k; ) design D is a system (multiset) of kelement subsets (called blocks) of a velement set V such that every telement subset of V occurs exactly times in the blocks of D. A t(v; k; ) design D is called indecomposable (or elementary) if and only if there is no subsystem which is a
On categories of indecomposable modules. I
 OSAKA JOURNAL OF MATHEMATICS. 7(2) P.323P.344
, 1970
"... One of the authors had defined a regular additive category and studied some structures of it in [15]. We shall give, in this note, several applications of [15], Theorem 2. In the first section, we take an injective module M over a ring R and consider the full subcategory C(M) of the category of rig ..."
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are coproducts of a given family {Ma} of completely indecomposable modules. Let $ ' be the ideal of W whose morphisms are all rootselements, (see the definition in [1]), then we shall show in Theorem 7 that 2Γ/3' is a completely reducible C3abelian category. We prove Azumaya's theorem as a
INDECOMPOSABLE LINEAR GROUPS
, 2007
"... Dedicated to the memory of Professor A.V. Roiter Abstract. Let G be a noncyclic group of order 4, and let K = Z, Z (2) and Z2 be the ring of rational integers, the localization of Z at the prime 2 and the ring of 2adic integers, respectively. We describe, up to conjugacy, all of the indecomposable ..."
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Dedicated to the memory of Professor A.V. Roiter Abstract. Let G be a noncyclic group of order 4, and let K = Z, Z (2) and Z2 be the ring of rational integers, the localization of Z at the prime 2 and the ring of 2adic integers, respectively. We describe, up to conjugacy, all of the indecomposable
Indecomposable, projective and flat Sposets
 Comm. Algebra
"... Abstract. For a monoid S, a (left) Sact is a nonempty set B together with a mapping S × B → B sending (s, b) to sb such that s(tb) = (st)b and 1b = b for all s, t ∈ S and b ∈ B. Right Sacts A can also be defined, and a tensor product A ⊗S B (a set) can be defined that has the customary universal ..."
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Cited by 4 (1 self)
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(Sposets). The present paper is devoted to such a generalization. A unique decomposition theorem for Sposets is given, based on strongly convex, indecomposable Ssubposets, and a structure theorem for projective Sposets is given. A criterion for when two elements of the tensor product of S
Indecomposable higher Chow cycles on Jacobians, preprint
"... Abstract. We construct some natural cycles with trivial regulator in the higher Chow groups of Jacobians. For hyperelliptic curves we use a criterion due to J. Lewis to prove that the cycles we construct are indecomposable, and then use a specialization argument to prove indecomposability for more g ..."
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Abstract. We construct some natural cycles with trivial regulator in the higher Chow groups of Jacobians. For hyperelliptic curves we use a criterion due to J. Lewis to prove that the cycles we construct are indecomposable, and then use a specialization argument to prove indecomposability for more
ON THE VERTICES OF INDECOMPOSABLE SUMMANDS OF CERTAIN LEFSCHETZ MODULES
"... ABSTRACT. We study the reduced Lefschetz module of the complex of pradical and pcentric subgroups. We assume that the underlying group G has parabolic characteristic p and the centralizer of a certain noncentral pelement has a component with central quotient H a finite group of Lie type in chara ..."
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ABSTRACT. We study the reduced Lefschetz module of the complex of pradical and pcentric subgroups. We assume that the underlying group G has parabolic characteristic p and the centralizer of a certain noncentral pelement has a component with central quotient H a finite group of Lie type
Repeated blocks in indecomposable twofold extended triple systems
, 1998
"... An extended triple system (a twofold extended triple system) with no idempotent element (ETS, TETS respectively) is a pair (V, B) where V is a vset and B is a collection of unordered triples, called blocks, of type {x,y,z} or {x,x,y}, such that each pair (whether distinct or not) is contained in ex ..."
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An extended triple system (a twofold extended triple system) with no idempotent element (ETS, TETS respectively) is a pair (V, B) where V is a vset and B is a collection of unordered triples, called blocks, of type {x,y,z} or {x,x,y}, such that each pair (whether distinct or not) is contained
INDECOMPOSABLE PD3COMPLEXES J.A.HILLMAN
"... Abstract. We show that if the fundamental group pi of an indecomposable PD3complex is the fundamental group of a finite graph of finite groups then the vertex groups have periodic cohomology and the edge groups are metacyclic. If the vertex groups all have cohomological period dividing 4 then the ..."
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is an orientable PD3complex then the centralizer of a nontrivial element of prime order must be finite. We shall use this observation repeatedly in §1 and §2. In Theorem 5 we show that ifX is indecomposable and π1(X) = πG for some finite graph G of finite groups then the vertex groups have periodic cohomology
Results 1  10
of
119