منابع مشابه
Characterizing path graphs by forbidden induced subgraphs
A path graph is the intersection graph of subpaths of a tree. In 1970, Renz asked for a characterization of path graphs by forbidden induced subgraphs. We answer this question by determining the complete list of graphs that are not path graphs and are minimal with this property. 2009 Wiley Periodicals, Inc. J Graph Theory 62: 369–384, 2009
متن کاملCharacterizing directed path graphs by forbidden asteroids
An asteroidal triple is a stable set of three vertices such that each pair is connected by a path avoiding the neighborhood of the third vertex. Asteroidal triples play a central role in a classical characterization of interval graphs by Lekkerkerker and Boland. Their result says that a chordal graph is an interval graph if and only if it does not contain an asteroidal triple. In this paper, we...
متن کاملColoring Graphs Characterized by a Forbidden Subgraph
The Coloring problem is to test whether a given graph can be colored with at most k colors for some given k, such that no two adjacent vertices receive the same color. The complexity of this problem on graphs that do not contain some graph H as an induced subgraph is known for each fixed graph H. A natural variant is to forbid a graph H only as a subgraph. We call such graphs strongly H-free an...
متن کاملRecognizing Interval Bigraphs by Forbidden Patterns
Let H be a connected bipartite graph with n vertices and m edges. We give an O(nm) time algorithm to decide whether H is an interval bigraph. The best known algorithm has time complexity O(nm(m + n) log n) and it was developed in 1997 [18]. Our approach is based on an ordering characterization of interval bigraphs introduced by Hell and Huang [13]. We transform the problem of finding the desire...
متن کاملAvoiding Forbidden Submatrices by Row Deletions
We initiate a systematic study of the Row Deletion(B) problem on matrices: For a fixed “forbidden submatrix” B, the question is, given an input matrix A (both A and B have entries chosen from a finite-size alphabet), to remove a minimum number of rows such that A has no submatrix which is equivalent to a row or column permutation of B. An application of this question can be found, e.g., in the ...
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ژورنال
عنوان ژورنال: The Lancet
سال: 1845
ISSN: 0140-6736
DOI: 10.1016/s0140-6736(02)87120-3