Báo cáo toán học: "Directed subgraph complexes" ppt

... yields the result via Lemma 3.1. 4 Not strongly connected subgraphs In this section we turn our attention to ∆ NSC G , the complex of subgraphs of G that are not strongly connected. More precisely, ∆ NSC G = ... partitions into strongly connected components of subgraphs of G. The partition corresponding to the electronic journal of combinatorics 11 (2004), #R75 4 Directed subgraph complexes...

Ngày tải lên: 07/08/2014, 08:22

Ngày tải lên: 07/08/2014, 05:23

... lattice of Figure 3. (That is, there is a finite subgraph of the lattice, such that any subregion H of the square-octagon lattice containing this subgraph will fail to be of the form H(G; v ∗ ,f ∗ ).) the ... the limit of the normalized logarithm of the number of spanning trees of large finite subgraphs of G, as the subgraphs grow to fill G? It is not too hard to guess the shape of the answe...

Ngày tải lên: 07/08/2014, 06:20

... forbidden subgraphs. Theorem 17 For any graphs G 1 =(V, E 1 ) and G 2 =(V, E 2 ) on a common vertex set, there exists a bound polysemic pair {G  1 ,G  2 } such that G 1 is an induced subgraph of ... polysemic pair {G  1 ,G  2 } such that G 1 is an induced subgraph of G  1 and G 2 is an induced subgraph of G  2 . Proof. For any edge clique covers E 1 = {Q 1,1 , ,Q 1,r } of G 1 and...

Ngày tải lên: 07/08/2014, 06:20

... H-factor of a graph G is a spanning subgraph of G whose connected com- ponents are isomorphic to H. Given a properly edge-colored graph G,arainbow H -subgraph of G is an H -subgraph of G whose edges have ... graphs. References [1] N. Alon, T. Jiang, Z. Miller and D. Pritikin, Properly colored subgraphs and rainbow subgraphs in edge-colorings with local constraints, Random Struct. Algorith...

Ngày tải lên: 07/08/2014, 13:21

Ngày tải lên: 07/08/2014, 15:23

... or an odd cycle. Then G contains an induced subgraph H, such that H is an even cycle with at most one chord. The next description of typical induced subgraphs of graphs with the heart non-empty and ... G has an induced subgraph H which is circular q-degree-choosable. Then we show that if the heart of G is non-empty and distinct from an odd cycle then G contains an induced subgraph with...

Ngày tải lên: 07/08/2014, 21:20

Ngày tải lên: 07/08/2014, 21:21

... C 4 and 2K 2 as induced subgraphs, while (O 2 ∪P 4 ) ∨O 2 contains both C 4 and P 4 as induced subgraphs. Further, (K 2 ∨ P 4 ) ∪ K 2 contains both P 4 and 2K 2 as induced subgraphs. Finally we also ... induced subgraphs equal to P 4 , C 4 , or 2K 2 . In light of that fact, it is natural to wonder whether the property of being an NT graph also places a restriction on the presence of subgraphs...

Ngày tải lên: 07/08/2014, 21:21

Ngày tải lên: 07/08/2014, 21:21