Title
On Linear Recognition of Tree-Width at Most Four
Abstract
A graph $G$ has tree-width at most $k$ if the vertices of $G$ can be decomposed into a tree-like structure of sets of vertices, each set having cardinality at most $k+1$. An alternate definition of tree-width is stated in terms of a $k$-elimination sequence, which is an order to eliminate the vertices of the graph such that each vertex, at the time it is eliminated from the graph, has degree at most $k$. Arnborg and Proskurowski showed that if a graph has tree-width at most a fixed $k$, then many NP-hard problems can be solved in linear time, provided this $k$-elimination sequence is part of the input. These algorithms are very efficient for small $k$, such as 2, 3, or 4, but may be impractical for large $k$ as they depend exponentially on $k$. A reduction process is developed, and reductions are shown that can be applied to a graph of tree-width at most four without increasing its tree-width. Further, each graph of tree-width at most four contains one of these reductions. The reductions are then used in a linear-time algorithm that generates a 4-elimination sequence, if one exists.
Year
DOI
Venue
1996
10.1137/S0895480193243043
SIAM J. Discrete Math.
Keywords
Field
DocType
elimination sequence,reduction process,linear-time algorithm,linear recognition,linear time,np-hard problem,tree-like structure,4-elimination sequence,alternate definition,tree width
Discrete mathematics,Combinatorics,Path (graph theory),Graph power,Cycle graph,Regular graph,Null graph,Distance-regular graph,Mathematics,Path graph,Complement graph
Journal
Volume
Issue
ISSN
9
1
0895-4801
Citations 
PageRank 
References 
26
1.68
1
Authors
1
Name
Order
Citations
PageRank
Daniel P. Sanders147145.56