Báo cáo toán học: "Skolem-type Difference Sets for Cycle Systems)" pot

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Ngày tải lên: 05/08/2014, 15:20

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Ngày tải lên: 05/08/2014, 15:20

... different if the ordering cone C is not pointed. So one must be careful when applying results in [4] for efficient points in the sense of (1) (as done in [2, p. 291]). For instance, Corollary 3.11 ... is efficient w.r.t. C in the sense of (2), while A has no efficient point w.r.t. C in the sense of (1). The set of efficient points of A w.r.t. C is called efficient set and denoted by...

Ngày tải lên: 06/08/2014, 05:20

... bounds and the best upper bounds known. For example the lower bound for M(15, 10) in [1] is 958, the lower bound using Lorentzen and Nilsen’s formulation is 962 and the lower bound in this paper is ... programming to prove lower bounds on the size of difference triangle sets. In this note we show how to improve these bounds by including additional valid linear inequalit...

Ngày tải lên: 07/08/2014, 06:20

... S of subsets of a finite set S whose union is S is connected if and only if there is an evolutionary path in S between any two members of S. Proof:IfS is a finite connected family of subsets of ... the members of i S [S] account for at least five of the seven nonempty subsets of S. Without losing generality we may assume that the complement in P(S) − {∅} of i S [S] is a subset...

Ngày tải lên: 07/08/2014, 06:20

... (v 2+p 1 +p 2 +···+p j ,v 2+p 1 +p 2 +···+p j +p j+1 )forj= 0,1,2, ,k−1. Note that upset arcs of an upset tournament form a path, which we call its upset path. An upset tournament T with vertices v 1 , ,v n is in standard form pro- vided ... T  = T , and thus α ∪ β is a score certificate for T . Later we will show that the bound in Theorem 2.2 is not sharp in general. The construc...

Ngày tải lên: 07/08/2014, 06:22

... theorem. Theorem 1 The size of a minimum connected dominating set of a random n-vertex cubic graph is asymptotically almost surely less than 0.5854n. Proof After the first element of C has been chosen, ... least to within an additive constant, of the main result of [10]. They also showed that the size of a connected dominating set of an n-vertex cubic graph of gir...

Ngày tải lên: 07/08/2014, 06:23

... +1| 2mt+1 = mt, the difference m-tuples obtained from a hooked Skolem-type m -cycle difference set of order t form a modulo v difference set that uses edges of lengths 1, 2, ,mt. Theorem 3.3 For all integers ... Skolem-type m -cycle difference set of size t. Hence it remains to construct a Skolem-type m -cycle difference set of size t whenever mt ≡ 0, 3(mod 4) and a hooked Skolem-ty...

Ngày tải lên: 07/08/2014, 08:20

... there is an r -ribbon of one of the given forms with its head on diagonal d k , with an increase of the sum for ribbons of the form à/, and a decrease of the sum for ribbons of the form /à;in either ... that these Knuth correspondences are not derived from Schensted correspondences by means of standardisation. That method does not work for general r -ribbon tableaux, since for...

Ngày tải lên: 07/08/2014, 08:22

... should be intersecting, we get that F should be intersecting and co -intersecting. So we conclude the following Claim 3.3. max{D(F, G):F, G are intersecting} =max{ρ(F):F is intersecting and co -intersecting} . ... hypergraphs, and clearly D(F, G) can t decrease. Case B  F = ∅. (or similarly  G = ∅) the electronic journal of combinatorics 12 (2005), #R24 2 How different can two...

Ngày tải lên: 07/08/2014, 08:22

... saturating sets in small projective geome- tries, European J. Combin. 21 (2000), 563–570. [7] A.A. Davydov, S. Marcugini and F. Pambianco, On saturating sets in projective spaces, J. Combin. Theory ... As well as being a natural geometrical problem, the construction of small dense sets in P G(2, q) is relevant in other areas of Combinatorics, as dense sets are related...

Ngày tải lên: 07/08/2014, 15:23

... coin sets. Finally, we ask about the asymptotics of the density of the set of totally greedy coin sets within the set of greedy coin sets. If G(k, R) denotes the set of all greedy coin sets with ... easy to test if a coin set is totally greedy. We begin to explore the theory of greedy obstructions– those coin sets that cannot be extended to greedy coin sets...

Ngày tải lên: 07/08/2014, 21:20

... 1: Numbers of chromatic polynomials of degree at most 10. (A) Total number of chromatic polynomials, (B) number of chromatic polynomials of clique-separable g r aphs and (C) number of chromatic ... 4705 Table 2: Chromatic factorisations of chromatic polynomials of degree n ≤ 10 of strongly non-clique-separable graph. 4 Certificates of Factorisation Definition A...

Ngày tải lên: 07/08/2014, 21:21

... y: w ≤ w ′ if wS ⊆ w ′ S for all G a nd all S ⊆ U. The focus of this paper is the partial order on the following semigroup: Definition 2. The quantifier semigroup for bipartite graphs, S, is defined ... can easily identify the electronic journal of combinatorics 18 (2011), #P123 7 The quantifier semigroup for bipartite graphs Leonard J. Schulman ∗ Submitted: Jun 22, 2010; Acc...

Ngày tải lên: 08/08/2014, 14:23

... Addition of an edge The second result that we present is on the change of the index when we add an edge to a graph. In this context, Rowlinson [9] proved that, under some conditions, the index of the ... of interest. First, they are derived from a mere knowledge of the degrees of the vertices involved in the perturbation. Second, they are the best possible,...

Ngày tải lên: 08/08/2014, 14:23