public override DecompositionTree Construct(Graph graph, WidthParameter widthparameter)
{
DecompositionTree tree = new DecompositionTree(graph, widthparameter);
// Create the leaves.
DecompositionNode[] nodes = new DecompositionNode[graph.Vertices.Count];
for (int i = 0; i < nodes.Length; i++)
{
tree.Nodes[i] = nodes[i] = new DecompositionNode(new BitSet(nodes.Length, graph.Vertices[i].Index), i, tree);
}
int size = nodes.Length;
while (size > 1)
{
// Find the pair of nodes whose combination is of minimal width.
double min = double.PositiveInfinity;
int first = -1, second = -1;
for (int i = 0; i < size; i++)
{
for (int j = i + 1; j < size; j++)
{
double width = widthparameter.GetWidth(graph, nodes[i].Set | nodes[j].Set);
if (width < min)
{
min = width;
first = i;
second = j;
}
}
}
// Create the parent and connect it to its children.
DecompositionNode node = new DecompositionNode(nodes[first].Set | nodes[second].Set, nodes.Length * 2 - size, tree);
tree.Attach(node, nodes[first], Branch.Left);
tree.Attach(node, nodes[second], Branch.Right);
tree.Nodes[node.Index] = node;
// Update the active set of nodes.
nodes[first] = node;
nodes[second] = nodes[size - 1];
size--;
}
tree.Attach(null, nodes[0], Branch.Left);
tree.ComputeWidth();
return(tree);
}
/// <summary>
/// Construct a linear decomposition tree from the given starting vertex.
/// </summary>
protected DecompositionTree construct(Graph graph, WidthParameter widthparameter, Vertex start)
{
DecompositionTree result = new DecompositionTree(graph, widthparameter);
int index = 0;
BitSet leftbits = new BitSet(graph.Vertices.Count, start.Index);
BitSet rightbits = ~leftbits;
BitSet neighborhood = new BitSet(start.Neighborhood);
this.add(result, start, index++);
while (!rightbits.IsEmpty)
{
Vertex selected = null;
double best = double.PositiveInfinity;
var candidates = this.candidates(graph, rightbits, leftbits, neighborhood);
foreach (var candidate in candidates)
{
BitSet left = new BitSet(leftbits);
left[candidate.Index] = true;
BitSet right = new BitSet(rightbits);
right[candidate.Index] = false;
double width = widthparameter.GetWidth(graph, left, right);
if (width < best)
{
best = width;
selected = candidate;
}
}
leftbits[selected.Index] = true;
rightbits[selected.Index] = false;
neighborhood.Or(selected.Neighborhood);
neighborhood[selected.Index] = false;
this.add(result, selected, index);
index += 2;
}
return(result);
}
public override DecompositionTree Construct(Graph graph, WidthParameter widthparameter)
{
DecompositionTree tree = new DecompositionTree(graph, widthparameter);
// Create the leaves.
DecompositionNode[] nodes = new DecompositionNode[graph.Vertices.Count];
for (int i = 0; i < nodes.Length; i++)
{
tree.Nodes[i] = nodes[i] = new DecompositionNode(new BitSet(nodes.Length, graph.Vertices[i].Index), i, tree);
}
int size = nodes.Length;
while (size > 1)
{
int first = this.rng.Next(size);
int second = this.rng.Next(size - 1);
if (second <= first)
{
second++;
}
// Create the parent and connect it to its children.
DecompositionNode node = new DecompositionNode(nodes[first].Set | nodes[second].Set, nodes.Length * 2 - size, tree);
tree.Attach(node, nodes[first], Branch.Left);
tree.Attach(node, nodes[second], Branch.Right);
tree.Nodes[node.Index] = node;
// Update the active set of nodes.
nodes[first] = node;
nodes[second] = nodes[size - 1];
size--;
}
tree.Attach(null, nodes[0], Branch.Left);
tree.ComputeWidth();
return(tree);
}
/// <summary> /// Construct a decomposition tree from the graph. /// </summary> /// <param name="graph">The graph that will be decomposed.</param> /// <param name="widthparameter">The width-parameter used to create the decomposition.</param> /// <returns>A binary decomposition tree of the graph.</returns> public abstract DecompositionTree Construct(Graph graph, WidthParameter widthparameter);
public static void RunUserTest()
{
Console.WriteLine("Path to graph file? Defaults to the anna graph from the TreewidthLIB set.");
string pathToGraph = Console.ReadLine();
if (pathToGraph.Length == 0)
{
pathToGraph = @"..\..\ExampleGraphs\anna.dgf";
}
Graph graph = Parser.ParseGraphFromDGF(pathToGraph);
Console.WriteLine("Width Parameter is (M)aximum-matching, (R)ank or (B)oolean? Defaults to rank-width.");
WidthParameter width = null;
string widthParameterString = Console.ReadLine().ToLower();
if (widthParameterString.Length == 0)
{
width = new RankWidth();
}
else
{
switch (widthParameterString.ToLower()[0])
{
case 'm':
width = new MaximumMatchingWidth();
break;
case 'b':
width = new BooleanWidth();
break;
default:
width = new RankWidth();
break;
}
}
Console.WriteLine("Local search duration in seconds? Defaults to 60 seconds.");
int localSearchDuration = 0;
if (!int.TryParse(Console.ReadLine(), out localSearchDuration))
{
localSearchDuration = 60;
}
Console.WriteLine("Seed for the random number generator? Defaults to a random seed.");
int seed = -1;
if (!int.TryParse(Console.ReadLine(), out seed))
{
Random r = new Random();
seed = r.Next();
Console.WriteLine("Seed is " + seed);
}
Random rng = new Random(seed);
Console.WriteLine("Should reduction rules be applied, (Y)es or (N)o? Defaults to yes.");
string reductionString = Console.ReadLine().ToLower();
bool useReductionRules = reductionString.Length == 0 || reductionString[0] != 'n';
double totalseconds = 0;
Console.WriteLine();
Console.WriteLine("---------------------- Starting -----------------------");
Console.WriteLine();
Graph[] graphs = null;
if (useReductionRules)
{
int originalvertexcount = graph.Vertices.Count;
Console.WriteLine($"Graph {Path.GetFileNameWithoutExtension(pathToGraph)} consists of {originalvertexcount} vertices.");
Console.WriteLine($"Applying the reduction rules...");
graphs = width.ApplyReductionRules(graph);
Console.WriteLine($"Number of vertices removed by the reduction rules = {originalvertexcount - graphs.Sum(g => g.Vertices.Count)}");
Console.WriteLine($"The reduction rules splitted the graph in {graphs.Length} subgraphs of sizes {string.Join(", ", graphs.Select(g => g.Vertices.Count))}.");
}
else
{
graphs = new Graph[] { graph }
};
Console.WriteLine();
Console.WriteLine("Constructing initial solution...");
Stopwatch sw = Stopwatch.StartNew();
ConstructionHeuristic constructor = new GreedyLinearConstructor(rng);
DecompositionTree[] trees = graphs.Select(g => constructor.Construct(g, width)).ToArray();
sw.Stop();
totalseconds += sw.ElapsedMilliseconds / 1000.0;
Console.WriteLine($"Finished construction of initial solution in {(sw.ElapsedMilliseconds / 1000).ToString("F2")} seconds.");
Console.WriteLine($"Initial {width.Name} = {string.Join(", ", trees.Select(tree => tree.Width.ToString("F2")))}");
Console.WriteLine($"Initial cost = {string.Join(", ", trees.Select(tree => tree.Cost.ToString("F2")))}");
Console.WriteLine();
Console.WriteLine("Improving solution with DP...");
sw.Restart();
OptimalOrderedTree oot = new OptimalOrderedTree();
trees = trees.Select(tree => oot.Construct(tree)).ToArray();
sw.Stop();
totalseconds += sw.ElapsedMilliseconds / 1000.0;
Console.WriteLine($"Finished DP in {(sw.ElapsedMilliseconds / 1000.0).ToString("F2")} seconds.");
Console.WriteLine($"Resulting {width.Name} = {string.Join(", ", trees.Select(tree => tree.Width.ToString("F2")))}");
Console.WriteLine($"Resulting cost = {string.Join(", ", trees.Select(tree => tree.Cost.ToString("F2")))}");
Console.WriteLine();
Console.WriteLine("Improving solution with local search...");
LocalSearchAlgorithm localsearch = new VariableNeighborhoodSearch(trees, new LocalSearchOperator[] { new MoveOperator(), new SwapOperator() }, rng);
localsearch.Run(localSearchDuration);
totalseconds += localsearch.CurrentComputationTime;
Console.WriteLine($"Finished local search in {localsearch.CurrentComputationTime.ToString("F2")} seconds.");
Console.WriteLine($"Total iterations = {localsearch.Iterations}");
Console.WriteLine($"Explored solutions = {localsearch.ExploredSolutions}");
Console.WriteLine($"Best {width.Name} = {string.Join(", ", trees.Select(tree => tree.Width.ToString("F2")))}");
Console.WriteLine($"Best cost = {string.Join(", ", trees.Select(tree => tree.Cost.ToString("F2")))}");
Console.WriteLine("Best decomposition trees:");
for (int i = 0; i < trees.Length; i++)
{
Console.WriteLine($"{i}: {trees[i].Root}");
}
Console.WriteLine();
Console.WriteLine("Cache statistics:");
Console.WriteLine($" request count = {width.CacheRequests}");
Console.WriteLine($" hit ratio = {width.CacheHitRatio.ToString("F3")}");
Console.WriteLine();
Console.WriteLine("Write result to disk? (Y)es / (N)o, defaults to Yes.");
string outputResponseString = Console.ReadLine().ToLower();
if (outputResponseString.Length == 0 || outputResponseString[0] == 'y')
{
Console.WriteLine("Output directory? Defaults to \\output.");
string outputDirectory = Console.ReadLine();
if (outputDirectory.Length == 0)
{
outputDirectory = "output";
}
Console.WriteLine($"Stored the result as {WriteResult(pathToGraph, outputDirectory, trees, seed, totalseconds)}");
}
else
{
Console.ReadLine();
}
}
public override DecompositionTree Construct(Graph graph, WidthParameter widthparameter)
{
int index = 0;
DecompositionTree tree = new DecompositionTree(graph, widthparameter);
DecompositionNode root = new DecompositionNode(~(new BitSet(tree.VertexCount)), index, tree);
tree.Nodes[index++] = root;
tree.Attach(null, root, Branch.Left);
List <DecompositionNode> candidates = new List <DecompositionNode>();
candidates.Add(root);
while (candidates.Count > 0)
{
// Select a random childless internal node.
DecompositionNode parent = candidates[this.rng.Next(candidates.Count)];
candidates.Remove(parent);
// Shuffle its set of vertices.
int[] indices = parent.Set.ToArray();
indices.Shuffle(this.rng);
// Split the set randomly into two non-empty sets.
int split = 1 + this.rng.Next(indices.Length - 2);
// Create its children.
DecompositionNode left = null;
if (split == 1)
{
left = new DecompositionNode(graph.Vertices[indices[0]], index, tree);
}
else
{
BitSet leftset = new BitSet(tree.VertexCount);
for (int i = 0; i < split; i++)
{
leftset[indices[i]] = true;
}
left = new DecompositionNode(leftset, index, tree);
candidates.Add(left);
}
tree.Nodes[index++] = left;
tree.Attach(parent, left, Branch.Left);
DecompositionNode right = null;
if (split == indices.Length - 1)
{
right = new DecompositionNode(graph.Vertices[indices[indices.Length - 1]], index, tree);
}
else
{
BitSet rightset = new BitSet(tree.VertexCount);
for (int i = split; i < indices.Length; i++)
{
rightset[indices[i]] = true;
}
right = new DecompositionNode(rightset, index, tree);
candidates.Add(right);
}
tree.Nodes[index++] = right;
tree.Attach(parent, right, Branch.Right);
}
tree.ComputeWidth();
return(tree);
}
public override DecompositionTree Construct(Graph graph, WidthParameter widthparameter)
{
return(this.construct(graph, widthparameter, graph.Vertices[this.random.Next(graph.Vertices.Count)]));
}
public DecompositionTree(DecompositionTree tree, WidthParameter width = null) : this(tree.Graph, width != null ? width : tree.WidthParameter)
{
this.Root = tree.Root.CopyTree(this, null);
}
public DecompositionTree(Graph graph, WidthParameter parameter)
{
this.Graph = graph;
this.WidthParameter = parameter;
this.Nodes = new DecompositionNode[graph.Vertices.Count * 2 - 1];
}