This repository contains the source code for evaluation of lower and upper bounds of the treewidth of undirected graphs. It implements a subset of the algorithms described in this paper and this paper.
The Makefile is in the main folder, so simply execute make:
make clean; make
The output binary is treedecomp.
The code needs the Boost C++ library headers, and specifically the Fibonacci heap implementation. It assumes the include files are present in /usr/local/include. If your Boost installation is someplace else, you have to modify the INCLUDE_DIRS directive in Makefile. The binary library does not need to be linked.
The program expects as input a graph in the following format, one edge per line:
node1 <TAB> node2
where node1 and node2 are the endpoints of the edge.
The usage is the following:
./treedecomp --upper|lower <graph_file> [<method> [<partial_degree>]]
The parameters are:
- upper|lower chooses between upper or lower bounds
- graph_file is the name of the graph file
- method is the criteria by which each node is chosen next in the decomposition sequence, and can have the following values: 0 minimum degree (default), 1 minimum fill in, and 2 minimum degree+fill in (only for upper bounds)
- partial_degree is the maximum degree at which the decomposition will stop; in this case, the output files will contain a partial decomposition -- this is useful for large graphs (only for upper bounds)
The output will be a file with the name ..dec containing the tree decomposition.
The format is the following:
<treewidth> <number_nodes> <node_list>
treewidth is a number representing the estimated treewidth, number_nodes is the number of nodes in the tree decomposition of the graph.
<node_list contains number_nodes blocks representing the tree nodes, each in the following format:
<node_id> <num_nodes> <node_list> <parent_id> <num_children> [<child_list>]
node_id is the id of the nodes, num_nodes is the number of graph nodes in the tree node, node_list is a whitespace delimited list of the nodes, parent_id is the id of the parent of the node in the tree, num_children is the number of child nodes in the tree, and child_list is the list of their ids (if any).
This code has been tested with the graph datasets available here
The source code is provided as-is under an MIT License.