منابع مشابه
Tree-chromatic number
Let us say a graph G has “tree-chromatic number” at most k if it admits a tree-decomposition (T, (Xt : t ∈ V (T ))) such that G[Xt] has chromatic number at most k for each t ∈ V (T ). This seems to be a new concept, and this paper is a collection of observations on the topic. In particular we show that there are graphs with tree-chromatic number two and with arbitrarily large chromatic number; ...
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We propose a Ramsey theory for binary trees and prove that for every r-coloring of “strong copies” of a small binary tree in a huge complete binary tree T , we can find a strong copy of a large complete binary tree in T with all small copies monochromatic. As an application, we construct a family of graphs which have treechromatic number at most 2 while the path-chromatic number is unbounded. T...
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Let G be a connected graph. Let f be a proper k -coloring of G and Π = (R_1, R_2, . . . , R_k) bean ordered partition of V (G) into color classes. For any vertex v of G, define the color code c_Π(v) of v with respect to Π to be a k -tuple (d(v, R_1), d(v, R_2), . . . , d(v, R_k)), where d(v, R_i) is the min{d(v, x)|x ∈ R_i}. If distinct vertices have distinct color codes, then we call f a locat...
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Let c be a vertex k -coloring on a connected graph G(V,E) . Let Π = {C1, C2, ..., Ck} be the partition of V (G) induced by the coloring c . The color code cΠ(v) of a vertex v in G is (d(v, C1), d(v, C2), ..., d(v, Ck)), where d(v, Ci) = min{d(v, x)|x ∈ Ci} for 1 ≤ i ≤ k. If any two distinct vertices u, v in G satisfy that cΠ(u) 6= cΠ(v), then c is called a locating k-coloring of G . The locatin...
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A classic result of Asplund and Grünbaum states that intersection graphs of axis-aligned rectangles in the plane are χ-bounded. This theorem can be equivalently stated in terms of path-decompositions as follows: There exists a function f : N → N such that every graph that has two path-decompositions such that each bag of the first decomposition intersects each bag of the second in at most k ver...
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ژورنال
عنوان ژورنال: Journal of Combinatorial Theory, Series B
سال: 2016
ISSN: 0095-8956
DOI: 10.1016/j.jctb.2015.08.002