A still better performance guarantee for approximate graph coloring
Information Processing Letters
Algorithms for weakly triangulated graphs
Discrete Applied Mathematics
Computers and Intractability: A Guide to the Theory of NP-Completeness
Computers and Intractability: A Guide to the Theory of NP-Completeness
Algorithmic Graph Theory and Perfect Graphs (Annals of Discrete Mathematics, Vol 57)
Algorithmic Graph Theory and Perfect Graphs (Annals of Discrete Mathematics, Vol 57)
Approximation algorithms for the weighted independent set problem in sparse graphs
Discrete Applied Mathematics
Note: Edge intersection graphs of systems of paths on a grid with a bounded number of bends
Discrete Applied Mathematics
Universality considerations in VLSI circuits
IEEE Transactions on Computers
On the bend-number of planar and outerplanar graphs
LATIN'12 Proceedings of the 10th Latin American international conference on Theoretical Informatics
Edge-intersection graphs of grid paths: The bend-number
Discrete Applied Mathematics
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The edge intersection graphs of paths on a grid (or EPG graphs) are graphs whose vertices can be represented as simple paths on a rectangular grid such that two vertices are adjacent if and only if the corresponding paths share at least one edge of the grid. We consider the case of single-bend paths, namely, the class known as B1-EPG graphs. The motivation for studying these graphs comes from the context of circuit layout problems. It is known that recognizing B1-EPG graphs is NP-complete, nevertheless, optimization problems when given a set of paths in the grid are of considerable practical interest. In this paper, we show that the coloring problem and the maximum independent set problem are both NP-complete for B1-EPG graphs, even when the EPG representation is given. We then provide efficient 4-approximation algorithms for both of these problems, assuming the EPG representation is given. We conclude by noting that the maximum clique problem can be optimally solved in polynomial time for B1-EPG graphs, even when the EPG representation is not given.