Báo cáo toán hoc:"Tiling tripartite graphs with 3-colorable graphs" pps

... theorem, Discrete Math. 308 (2008), no. 19, 4337–4360. [21] R. Martin, Y. Zhao, Tiling tripartite graphs with 3-colorable graphs: The extreme case, preprint. [22] A. Shokoufandeh, Y. Zhao, Proof of a ... contradiction.  the electronic journal of combinatorics 16 (2009), #R109 4 Tiling tripartite graphs with 3-colorable graphs Ryan Martin ∗ Iowa State University Ames, IA 50...

Ngày tải lên: 08/08/2014, 01:20

Ngày tải lên: 05/08/2014, 15:20

... T = (T ; φ) is an ordered pair consisting of a tree T , with vertex set V say, and a map φ : X → V with the property that, for all v ∈ V with degree at most two, v ∈ φ(X). X-trees are commonly ... logarithmically with the size of its maximum vertex degree. To establish this result, we first prove the following lemma. An X-tree T = (T; φ) is a d-star if T is a star tree with d leaves...

Ngày tải lên: 07/08/2014, 13:21

... Theorem 3. This improves Denley’s Theorem 4. References 1. Denley, T., The Independence number of graphs with large odd girth, The Electronic Journal of Combinatorics 1 (1994) #R9. 2 We can now prove ... Denley’s Theorems 1 and 2. It is sharp for the regular complete bipartite graphs K aa . The above results are readily extended to graphs of larger odd girth. Lemma 2: Let G have odd g...

Ngày tải lên: 07/08/2014, 06:20

... Although almost all graphs are 3-e.c., the only known examples of strongly regular 3-e.c. graphs are Paley graphs with at least 29 vertices. We construct a new infinite family of 3-e.c. graphs, based ... strongly regular 3-e.c. graphs that are not Paley graphs. Some of them, however, do have the same parameters. For example, there are 3-e.c. graphs that are not Paley graphs, but...

Ngày tải lên: 07/08/2014, 06:22

... Die Theorie der regul¨aren graphs, Acta Math. 15 (1891) 193–220. [7] W.T. Tutte, The factors of graphs, Canad. J. Math. 4 (1952) 314–328. [8] L. Volkmann, Regular graphs, regular factors, and ... 1 For regular graphs without a k-factor, for odd k, we can give the following result on the subsets D and S. Lemma 2.3 Let n, k, d be integers such that n is even and k is odd with n>d>k...

Ngày tải lên: 07/08/2014, 08:20

... necessary condition for the tripartite state of the density matrices of nearest point graphs. 2 The tripartite entanglement properties of the den- sity matrices of graphs Recall that from [8] ... ρ(H i k j k ) is pure. Before we discuss the tripartite entanglement properties of the density matrices of graphs we will at first recall briefly the definition of the tripartite separabil...

Ngày tải lên: 07/08/2014, 15:22

... planar decomposition with the same properties. We have the following characterisation of graphs with linear minor crossing number, which is analogous to Theorem 3 for crossing number (without the dependence ... for simple cubic graphs [19, 31]. Moreover, the exact or even asymptotic crossing number is not known for specific graph families, such as complete graphs [40], complete bipar...

Ngày tải lên: 07/08/2014, 15:22

... Graham, R.L.: Quasi-random graphs with with given degree sequences. Random Structures and Algorithms 32 (2008) 1–19 [7] Chung, F., Lu, L.: Connected components in random graphs with given expected degree ... The spectra of random graphs with given expected degrees. Internet Mathematics 1 (2003) 257–275 [9] Coja-Oghlan, A., Lanka, A.: Finding planted partitions in random graphs...

Ngày tải lên: 08/08/2014, 01:20

... without backtracking or tails in the graphs Cooper proposed. Our method is flexible enough that we are able to generalize Cooper’s graphs, and we demonstrate add itional families of pairs of graphs ... leaves two connected components: one with n − 2 vertices and one with 2 vertices. We denote by R n the component with n − 2 vertices and by Z l the compo nent with 2 vertices. Simil...

Ngày tải lên: 08/08/2014, 12:22