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COMBINATORICS
2000
13 years 7 months ago
2000
A mixed hypergraph is a triple H = (V, C, D) where V is the vertex set and C and D are families of subsets of V , the C-edges and D-edges, respectively. A k-colouring of H is a ma...
EJC
2007
13 years 7 months ago
2007
Let Φ be an irreducible root system and ∆ be a base for Φ; it is well known that any root in Φ is an integral combination of the roots in ∆. In comparison to this fact, we ...
DM
2008
13 years 7 months ago
2008
A (p, 1)-total labelling of a graph G is an assignment of integers to V (G) E(G) such that: (i) any two adjacent vertices of G receive distinct integers, (ii) any two adjacent ed...
COLOGNETWENTE
2010
13 years 6 months ago
2010
An interval total t coloring of a graph G is a total coloring of with colors 1, such that at least one vertex or edge of is colored by color − G 2, ,t… G , 1, 2, ,i i t= … ,...
FOCS
2002
IEEE
14 years 10 days ago
2002
IEEE
We prove that coloring a 3-uniform 2-colorable hypergraph with c colors is NP-hard for any constant c. The best known algorithm [20] colors such a graph using O(n1/5 ) colors. Our...