Exemplo n.º 1
0
        public static Dictionary <PartialSolution, int> Reduce_M4R(Dictionary <PartialSolution, int> table, double tr)
        {
            // No point further reducing something empty
            if (!table.Any() || table.First().Key.Subset == null)
            {
                return(table);
            }

            int nv = table.First().Key.Subset.LocalSubset.BitCount();

            // Not worth reducing
            if (table.Count * tr <= (1 << (nv - 1)))
            {
                return(table);
            }

            Dictionary <PartialSolution, int> result;

            if (nv <= 1)
            {
                KeyValuePair <PartialSolution, int> minSol = table.Where((s) => s.Value == table.Values.Min()).First();
                result = new Dictionary <PartialSolution, int>();
                result.Add(minSol.Key, minSol.Value);
                return(result);
            }

            RankBased irb = new RankBased(table.First().Key.Subset);

            result = irb.M4RReduce(table);

            RankBased.ClearPool();

            return(result);
        }
Exemplo n.º 2
0
        public Dictionary <PartialSolution, int> IntroduceEdgesIntoTable(Dictionary <PartialSolution, int> table, Edge[] edges)
        {
            if (table.Count == 0 || edges.Length == 0)
            {
                return(table);
            }

            Dictionary <PartialSolution, int> result = new Dictionary <PartialSolution, int>();
            RankBased irb = new RankBased(table.First().Key.Subset);

            PriorityQueue <PartialSolution> pq = new PriorityQueue <PartialSolution>(table.Count * 2);

            foreach (KeyValuePair <PartialSolution, int> kvp in table)
            {
                pq.Enqueue(kvp.Key, kvp.Value);
            }

            HashSet <PartialSolution> seen = new HashSet <PartialSolution>();

            while (!pq.IsEmpty())
            {
                int             weight = (int)pq.PeekDist();
                PartialSolution ps     = pq.Dequeue();

                // HashSet is faster than RankBased
                if (!seen.Add(ps))
                {
                    continue;
                }

                // Solution is already represented by output
                if (!irb.AddSolution(ps))
                {
                    continue;
                }


                result.Add(ps, weight);
                Upsert(result, ps, weight);

                // Add edges to ps. Note that adding edges is not necessary if solution is already represented (since we could have added the same edges to the representatives instead)
                foreach (Edge e in edges)
                {
                    if (ps.Find(e.To.Color) == ps.Find(e.From.Color))
                    {
                        continue;
                    }
                    PartialSolution newSol = new PartialSolution(ps.Subset, ps);
                    newSol.Union(e.To.Color, e.From.Color);
                    pq.Enqueue(newSol, weight + e.Weight);
                }
            }

            RankBased.ClearPool();

            return(result);
        }
Exemplo n.º 3
0
        public Dictionary <int, Dictionary <PartialSolution, int> > Forget(TDNode bag, Vertex[] vertices, Dictionary <int, Dictionary <PartialSolution, int> > table)
        {
            forgetSW.Start();

            Dictionary <int, Dictionary <PartialSolution, int> > result = new Dictionary <int, Dictionary <PartialSolution, int> >();

            int vertexMask = 0;

            foreach (Vertex v in vertices)
            {
                vertexMask |= (1 << v.Color);
            }

            byte[] tempUF = new byte[bag.ParentDecomposition.Width];

            foreach (KeyValuePair <int, Dictionary <PartialSolution, int> > kvp in table)
            {
                int subset    = kvp.Key;
                int newSubset = subset & ~vertexMask;
                Dictionary <PartialSolution, int> newDict = null;
                if (!result.TryGetValue(newSubset, out newDict))
                {
                    newDict = new Dictionary <PartialSolution, int>();
                    result.Add(newSubset, newDict);
                }

                foreach (KeyValuePair <PartialSolution, int> kvp2 in kvp.Value)
                {
                    if (kvp2.Key.CountComponents() != kvp2.Key.CountComponents(newSubset))
                    {
                        continue;                                                                    // Check whether set remains connected
                    }
                    VertexSubset    newVertexSubset = VertexSubset.Create(bag, newSubset, kvp2.Key.Subset, null);
                    PartialSolution newPs           = new PartialSolution(newVertexSubset, kvp2.Key);
                    Upsert(newDict, newPs, kvp2.Value);
                }
            }

            foreach (KeyValuePair <int, Dictionary <PartialSolution, int> > kvp in table.ToList())
            {
                table[kvp.Key] = RankBased.Reduce(kvp.Value, 0.125);
            }

            forgetSW.Stop();

            Program.TableCount += result.Values.Sum((t) => t.Count);

            return(result);
        }
Exemplo n.º 4
0
        // Joins two tables that have partial solutions with one type of vertex subset
        public Dictionary <PartialSolution, int> JoinTwo(TDNode bag, List <int> verticesInvolved, Dictionary <PartialSolution, int> leftTable, Dictionary <PartialSolution, int> rightTable)
        {
            Dictionary <PartialSolution, int> newTable = new Dictionary <PartialSolution, int>();

            // Reducing before Join is almost certainly beneficial, use a low threshold
            leftTable  = RankBased.Reduce(leftTable, 0.999);
            rightTable = RankBased.Reduce(rightTable, 0.999);

            KeyValuePair <PartialSolution, int>[] rightCopy = rightTable.ToArray();

            foreach (KeyValuePair <PartialSolution, int> leftSol in leftTable)
            {
                foreach (KeyValuePair <PartialSolution, int> rightSol in rightCopy)
                {
                    VertexSubset    newSubset = VertexSubset.Create(bag, leftSol.Key.Subset.LocalSubset, leftSol.Key.Subset, rightSol.Key.Subset);
                    PartialSolution newSol    = new PartialSolution(newSubset, leftSol.Key);

                    bool good = true;
                    foreach (int i in verticesInvolved)
                    {
                        byte rep = rightSol.Key.Find(i);
                        if (rep == i)
                        {
                            continue;
                        }
                        if (newSol.Find(i) == newSol.Find(rep))
                        {
                            good = false; break;
                        }
                        newSol.Union(i, rep);
                    }

                    if (good)
                    {
                        Upsert(newTable, newSol, leftSol.Value + rightSol.Value);
                    }
                }
            }

            // Do not call reduce here: the forget, introduce or join bag that comes next will take care of it
            //newTable = RankBased.Reduce(newTable, 0.5);

            return(newTable);
        }
Exemplo n.º 5
0
        public Dictionary <int, Dictionary <PartialSolution, int> > Introduce(TDNode bag, Vertex[] vertices, Dictionary <int, Dictionary <PartialSolution, int> > table)
        {
            introSW.Start();

            Vertex[] terminals    = vertices.Where((v) => v.IsTerminal).ToArray();
            Vertex[] nonterminals = vertices.Where((v) => !v.IsTerminal).ToArray();

            Dictionary <int, Dictionary <PartialSolution, int> > result = new Dictionary <int, Dictionary <PartialSolution, int> >();

            for (int i = 0; i < (1 << nonterminals.Length); i++)
            {
                List <Vertex> toAdd = new List <Vertex>(terminals.Length + i.BitCount());
                foreach (Vertex v in terminals)
                {
                    toAdd.Add(v);
                }
                for (int j = 0; j < nonterminals.Length; j++)
                {
                    if ((i & (1 << j)) != 0)
                    {
                        toAdd.Add(nonterminals[j]);
                    }
                }

                int addMask = 0;
                foreach (Vertex v in toAdd)
                {
                    addMask |= (1 << v.Color);
                }

                List <Edge> introEdges = new List <Edge>();
                foreach (Vertex v in toAdd)
                {
                    foreach (Edge e in v.Adj)
                    {
                        if (bag.Bag.Contains(e.To) && !introEdges.Contains(e))
                        {
                            introEdges.Add(e);
                        }
                    }
                }

                foreach (KeyValuePair <int, Dictionary <PartialSolution, int> > kvp in table)
                {
                    int subset    = kvp.Key;
                    int newSubset = subset | addMask;
                    Dictionary <PartialSolution, int> newDict = new Dictionary <PartialSolution, int>();

                    Dictionary <PartialSolution, int> localTable = RankBased.Reduce(kvp.Value, 0.999);

                    foreach (KeyValuePair <PartialSolution, int> kvp2 in localTable)
                    {
                        VertexSubset newVertexSubset = VertexSubset.Create(bag, newSubset, kvp2.Key.Subset, null);
                        newDict.Add(new PartialSolution(newVertexSubset, kvp2.Key), kvp2.Value);
                    }

                    if (introEdges.Where((e) => (newSubset & (1 << e.To.Color)) != 0).Count() > 2)
                    {
                        // Efficient method of introducing multiple edges at once and simultaneously running RankBased Reduce
                        //newDict = IntroduceEdgesIntoTable(newDict, introEdges.Where((e) => (newSubset & (1 << e.To.Color)) != 0).ToArray());
                        newDict = IntroduceEdgesIntoTable(newDict, introEdges.Where((e) => (newSubset & (1 << e.To.Color)) != 0).ToArray());
                    }
                    else
                    {
                        foreach (Edge e in introEdges)
                        {
                            if ((newSubset & (1 << e.To.Color)) != 0)
                            {
                                newDict = RankBased.Reduce(IntroduceEdge(newDict, e), 0.125);
                            }
                        }
                    }

                    if (newDict.Count > 0)
                    {
                        result.Add(newSubset, newDict);
                    }
                }
            }

            introSW.Stop();

            Program.TableCount += result.Values.Sum((t) => t.Count);

            return(result);
        }
Exemplo n.º 6
0
        // Different strategy for JoinTwo
        // The column obtained by joining two partial solutions is the bitwise AND of the columns corresponding to both solutions
        // Exploits this to attempt to speed up RBA
        public Dictionary <PartialSolution, int> JoinTwoIncremental(TDNode bag, List <int> verticesInvolved, Dictionary <PartialSolution, int> leftTable, Dictionary <PartialSolution, int> rightTable)
        {
            Dictionary <PartialSolution, int> newTable = new Dictionary <PartialSolution, int>();

            RankBased irbL = new RankBased(leftTable.First().Key.Subset);
            RankBased irbR = new RankBased(rightTable.First().Key.Subset);

            Tuple <KeyValuePair <PartialSolution, int>, Vector <uint>[]>[] leftSolutions  = leftTable.OrderBy((kvp2) => kvp2.Value).Select((s) => Tuple.Create(s, irbL.GetColumn(s.Key))).ToArray();
            Tuple <KeyValuePair <PartialSolution, int>, Vector <uint>[]>[] rightSolutions = rightTable.OrderBy((kvp2) => kvp2.Value).Select((s) => Tuple.Create(s, irbR.GetColumn(s.Key))).ToArray();

            if (leftSolutions.Length > (1 << (verticesInvolved.Count - 1)))
            {
                for (int i = 0; i < leftSolutions.Length; i++)
                {
                    if (!irbL.AddSolution(leftSolutions[i].Item1.Key, leftSolutions[i].Item2))
                    {
                        leftSolutions[i] = null;
                    }
                }
            }
            if (rightSolutions.Length > (1 << (verticesInvolved.Count - 1)))
            {
                for (int i = 0; i < rightSolutions.Length; i++)
                {
                    if (!irbR.AddSolution(rightSolutions[i].Item1.Key, rightSolutions[i].Item2))
                    {
                        rightSolutions[i] = null;
                    }
                }
            }

            leftSolutions  = leftSolutions.Where((s) => s != null).ToArray();
            rightSolutions = rightSolutions.Where((s) => s != null).ToArray();

            Tuple <PartialSolution, PartialSolution, Vector <uint>[], Vector <uint>[], int>[] joinedSolutions = new Tuple <PartialSolution, PartialSolution, Vector <uint>[], Vector <uint>[], int> [leftSolutions.Length * rightSolutions.Length];
            int pos = 0;

            foreach (Tuple <KeyValuePair <PartialSolution, int>, Vector <uint>[]> ls in leftSolutions)
            {
                foreach (Tuple <KeyValuePair <PartialSolution, int>, Vector <uint>[]> rs in rightSolutions)
                {
                    joinedSolutions[pos++] = Tuple.Create(ls.Item1.Key, rs.Item1.Key, ls.Item2, rs.Item2, ls.Item1.Value + rs.Item1.Value);
                }
            }

            joinedSolutions = joinedSolutions.OrderBy((s) => s.Item5).ToArray();

            //leftTable = RankBasedReduce(leftTable, 1);
            //rightTable = RankBasedReduce(rightTable, 1);

            RankBased irbJoined = new RankBased(leftTable.First().Key.Subset);

            HashSet <PartialSolution> psSeen = new HashSet <PartialSolution>();

            foreach (Tuple <PartialSolution, PartialSolution, Vector <uint>[], Vector <uint>[], int> pair in joinedSolutions)
            {
                VertexSubset    newSubset = VertexSubset.Create(bag, pair.Item1.Subset.LocalSubset, pair.Item1.Subset, pair.Item2.Subset);
                PartialSolution newSol    = new PartialSolution(newSubset, pair.Item1);

                bool good = true;
                foreach (int i in verticesInvolved)
                {
                    byte rep = pair.Item2.Find(i);
                    if (rep == i)
                    {
                        continue;
                    }
                    if (newSol.Find(i) == newSol.Find(rep))
                    {
                        good = false; break;
                    }
                    newSol.Union(i, rep);
                }

                if (!good || !psSeen.Add(newSol))
                {
                    continue;
                }

                Vector <uint>[] joinedColumn = RankBased.GetArray();
                RankBased.AND(pair.Item3, pair.Item4, joinedColumn, irbJoined.rowCountVector);
                if (!irbJoined.AddSolution(newSol, joinedColumn))
                {
                    RankBased.ReleaseArray(joinedColumn);
                    continue;
                }

                newTable.Add(newSol, pair.Item5);
            }

            RankBased.ClearPool();

            return(newTable);
        }