public void IntroduceLate(TDNode parent)
{
foreach (TDNode n in Adj)
{
if (n != parent)
{
n.IntroduceLate(this);
}
}
for (int i = 0; i < OptimizedBag.Length; i++)
{
Vertex v = OptimizedBag[i];
// Check if v is introduced
if (Adj.Any((n) => n != parent && n.BagContains(v)))
{
continue;
}
// Must introduce before forgetting
if (!parent.BagContains(v))
{
continue;
}
// v is not introduced, check if we can delay
if (v.Adj.Any((e) =>
{
Vertex w = e.To;
return(BagContains(w) && !parent.BagContains(w));
}))
{
continue;
}
// Delay introduction, remove v from bag
OptimizedBag[i] = null;
OptimizedByColor[v.Color] = null;
}
OptimizedBag = OptimizedBag.Where((v) => v != null).ToArray();
}
public T IntroduceIfNecessary <T>(IDPAlgorithm <T> algorithm, TDNode child, T table)
{
Vertex[] toIntroduce = Bag.Where((v) => !child.BagContains(v)).ToArray();
if (toIntroduce.Length > 0)
{
return(algorithm.Introduce(this, toIntroduce, table));
}
return(table);
}
// Adds a forget bag before any introduce
public void ForgetBeforeIntroduce(TDNode parent)
{
IEnumerable <TDNode> children = Adj.Where((n) => n != parent);
if (children.Count() == 1)
{
TDNode child = children.First();
IEnumerable <Vertex> toForget = child.Bag.Where((v) => !this.BagContains(v));
IEnumerable <Vertex> toIntroduce = this.Bag.Where((v) => !child.BagContains(v));
if (toForget.Any() && toIntroduce.Any())
{
TDNode newNode = new TDNode(0, ParentDecomposition, VertexByColor.Length);
newNode.Bag = child.Bag.Where((v) => this.BagContains(v)).ToArray();
foreach (Vertex v in newNode.Bag)
{
newNode.VertexByColor[v.Color] = v;
}
this.Adj.Remove(child);
this.Adj.Add(newNode);
child.Adj.Remove(this);
child.Adj.Add(newNode);
newNode.Adj.Add(child);
newNode.Adj.Add(this);
ParentDecomposition.Nodes.Add(newNode);
newNode.ForgetBeforeIntroduce(this);
return;
}
child.ForgetBeforeIntroduce(this);
return;
}
foreach (TDNode child in children)
{
child.ForgetBeforeIntroduce(this);
}
}
public T Compute <T>(IDPAlgorithm <T> algorithm, TDNode parent)
{
VertexSubset.ClearLookup();
// Note: through preprocessing, certain subtrees might have become empty. Do not consider.
IEnumerable <TDNode> children = Adj.Where((n) => n != parent && n.Subtree.Any());
if (children.Count() == 0)
{
return(algorithm.IntroduceEdges(algorithm.Introduce(this, Bag, algorithm.Leaf(ParentDecomposition.Width)), introduceEdges));
}
if (children.Count() == 1)
{
TDNode child = children.First();
Vertex[] toForget = child.Bag.Where((v) => !this.BagContains(v)).OrderBy((v) => v.Adj.Where((w) => BagContains(w.To)).Count()).Reverse().ToArray();
Vertex[] toIntroduce = this.Bag.Where((v) => !child.BagContains(v)).ToArray();
if (toIntroduce.Length > 0)
{
return(algorithm.IntroduceEdges(algorithm.Introduce(this, toIntroduce, child.Compute(algorithm, this)), introduceEdges));
}
if (toForget.Length > 0)
{
return(algorithm.IntroduceEdges(algorithm.Forget(this, toForget, child.Compute(algorithm, this)), introduceEdges));
}
// No change?
return(algorithm.IntroduceEdges(child.Compute(algorithm, this), introduceEdges));
}
if (children.Count() > 2)
{
throw new Exception("TD not preprocessed!");
}
TDNode left = children.ElementAt(0), right = children.ElementAt(1);
return(algorithm.IntroduceEdges(algorithm.Join(this, IntroduceIfNecessary(algorithm, left, left.Compute(algorithm, this)), IntroduceIfNecessary(algorithm, right, right.Compute(algorithm, this))), introduceEdges));
}