public static Var DecideVariableCountBased(List <Var> variables, CNSat solver)
{
int vars = variables.Count;
Lit l = null;
int maxCount = Int32.MaxValue;
int minCount = -1;
for (int i = 0; i < vars; i++)
{
if (variables[i].Assignment != Assignment.Unassigned)
{
continue;
}
for (int j = 0; j < variables[i].WatchList.Count; j++)
{
if (!variables[i].WatchList[j].Clause.Satisfied)
{
/*if(maxCount>variables[i].WatchList[j].Lit.VariableCount) {
* l = variables[i].WatchList[j].Lit;
* maxCount = l.VariableCount;
* }*/
if (minCount < variables[i].WatchList[j].Lit.VariableCount)
{
l = variables[i].WatchList[j].Lit;
minCount = l.VariableCount;
}
}
}
}
if (l == null)
{
return(null);
}
Assignment ass;
Var v = l.Var;
ass = l.Sign;
DecisionLevel d = new DecisionLevel(solver.Decisions.Count);
solver.DecisionLevel.Add(d);
v.Assignment = ass;
solver.Decisions.Add(v);
v.Reason = null;
v.DecisionLevel = d;
return(v);
}
public void AddChecked(Lit l)
{
bool found = false;
if (l.IsTemporary)
{
for (int i = 0; i < this.Literals.Count; i++)
{
if (this.Literals[i].IsTemporary && l.Atom == this.Literals[i].Atom)
{
found = true;
break;
}
}
if (!found)
{
Literals.Add(l);
} //else { }
return;
}
for (int i = 0; i < this.Literals.Count; i++)
{
if (l.Atom == this.Literals[i].Atom)
{
found = true;
if (l.Sign != this.Literals[i].Sign)
{
this.IsTautologic = true;
this.Literals.Clear();
}
//else {}
break;
}
}
if (!found)
{
Literals.Add(l);
}
return;
}
protected void DoTransform(LinkedList <Clause> clauses)
{
Clause curClause = null;
Lit curLit = null;
int j = 0;
LinkedListNode <Clause> clauseNode = clauses.First;
while (clauseNode != null)
{
if (!clauseNode.Value.IsFinished)
{
bool finished = true;
for (j = 0; j < clauseNode.Value.Literals.Count; j++)
{
if (clauseNode.Value.Literals[j].IsTemporary)
{
finished = false;
curClause = clauseNode.Value;
curLit = curClause.Literals[j];
break;
}
}
if (!finished)
{
//break clause on lit:
LinkedListNode <Clause> prevNode = clauseNode.Previous;
clauses.Remove(clauseNode);
curClause.Literals.RemoveAt(j);
Clause nc1, nc2;
PerformStep(curClause, curLit, out nc1, out nc2);
if (nc1 != null)
{
clauses.AddLast(nc1);
}
if (nc2 != null)
{
clauses.AddLast(nc2);
}
if (prevNode == null)
{
clauseNode = clauses.First;
}
else
{
clauseNode = prevNode.Next;
}
}
else
{
clauseNode.Value.IsFinished = true;
clauseNode = clauseNode.Next;
}
}
else
{
clauseNode = clauseNode.Next;
}
}
/*
* for(i=0; i<clauses.Count;i++) {
* if (clauses[i].IsFinished) {
* continue;
* }
* bool finished = true;
* for(j=0; j < clauses[i].Literals.Count; j++) {
* if(clauses[i].Literals[j].IsTemporary) {
* finished = false;
* curClause = clauses[i];
* curLit = curClause.Literals[j];
* break;
* }
* }
* if(!finished) {
* //break clause on lit:
* clauses.RemoveAt(i);
* curClause.Literals.RemoveAt(j);
* clauses.AddRange(PerformStep(curClause,curLit));
* i--;
*
* } else {
* clauses[i].IsFinished = true;
* }
* }
*/
/*foreach(Clause c in clauses) {
* if(!c.IsFinished) throw new Exception("Not Finished");
* }*/
}
protected void PerformStep(Clause c, Lit lit, out Clause newClause1, out Clause newClause2)
{
//List<Clause> ret = new List<Clause>();
Term formula = lit.Atom;
if (formula is Max)
{
Max m = (Max)formula;
Lit l = new Lit(m.Left, Assignment.Unassigned, true);
Lit r = new Lit(m.Right, Assignment.Unassigned, true);
c.AddChecked(l);
c.AddChecked(r);
newClause1 = c;
newClause2 = null;
return;
}
if (formula is And)
{
And m = (And)formula;
Lit l = new Lit(m.Left, Assignment.Unassigned, true);
Lit r = new Lit(m.Right, Assignment.Unassigned, true);
Clause c2 = c.Clone();
c.AddChecked(l);
c2.AddChecked(r);
newClause1 = c;
newClause2 = c2;
return;
}
if (formula is Or)
{
Or m = (Or)formula;
Lit l = new Lit(m.Left, Assignment.Unassigned, true);
Lit r = new Lit(m.Right, Assignment.Unassigned, true);
c.AddChecked(l);
c.AddChecked(r);
newClause1 = c;
newClause2 = null;
return;
}
if (formula is Min)
{
Min m = (Min)formula;
Lit l = new Lit(m.Left, Assignment.Unassigned, true);
Lit r = new Lit(m.Right, Assignment.Unassigned, true);
Clause c2 = c.Clone();
c.AddChecked(l);
c2.AddChecked(r);
newClause1 = c;
newClause2 = c2;
return;
}
if (formula is LTConstraint)
{
lit.IsTemporary = false;
lit.ComputeVariableCount();
lit.Sign = Assignment.True;
this.AtomOccurrence++;
Var v = null;
#if USE_EXTENDED_EQUALITY
if (this.TryGetVar(lit.Atom, out v))
{
#else
if (this.Atoms.TryGetValue(lit.Atom, out v))
{
#endif
lit.Var = v;
}
else
{
lit.Var = solver.newVar();
lit.Var.Term = lit.Atom;
this.Atoms.Add(lit.Atom, lit.Var);
}
c.AddChecked(lit);
newClause1 = c;
newClause2 = null;
return;
}
if (formula is LTEConstraint)
{
lit.IsTemporary = false;
lit.ComputeVariableCount();
lit.Sign = Assignment.False;
this.AtomOccurrence++;
Term p = ((LTEConstraint)formula).Negate();
lit.Atom = p;
Var v = null;
#if USE_EXTENDED_EQUALITY
if (this.TryGetVar(p, out v))
{
#else
if (this.Atoms.TryGetValue(p, out v))
{
#endif
lit.Var = v;
}
else
{
lit.Var = solver.newVar();
lit.Var.Term = p;
this.Atoms.Add(p, lit.Var);
}
c.AddChecked(lit);
newClause1 = c;
newClause2 = null;
return;
}
if (formula is Constant)
{
if (((Constant)formula).Value <= 0.0)
{
newClause1 = c;
}
else
{
newClause1 = null;
}
newClause2 = null;
return;
}
Console.Error.WriteLine("U C: {0}", formula);
throw new Exception("Unknown constraint in transformation: " + formula);
}
public Watcher(Lit l, Clause parent)
{
this.Clause = parent;
this.Lit = l;
Lit.Var.WatchList.Add(this);
}
public bool resolveConflict(Clause c)
{
++conflictCount;
//Learn Clause from conflict here
Clause confl = c;
Clause learnt = new Clause();
int index = decisions.Count - 1;
int pathC = 0;
Var p = null;
#if (CNSatDebug)
Console.WriteLine("\nxxxxxxxxxxxxxxxxxxx");
Console.WriteLine("\nAlready Learned");
foreach (Clause a in satClauses)
{
a.Print();
}
Console.WriteLine("\nAssignment");
this.PrintAssignments();
Console.WriteLine("\nConflict");
confl.Print();
Console.WriteLine("\nReason");
if (confl.LastModVar != null && confl.LastModVar.Reason != null)
{
confl.LastModVar.Reason.Print();
}
else
{
Console.WriteLine("null");
}
Console.WriteLine("-------------------\nLearning");
#endif
//Find all Literals until First Unique Implication Point(UIP)
do
{
#if (CNSatDebug)
if (p != null)
{
Console.Write("Var "); p.Print(); Console.Write(" -> ");
}
confl.Print();
Console.Write("Trying ");
#endif
Clause cl = confl;
//Inspect conflict reason clause Literals
for (int j = 0; j < cl.Literals.Count; j++)
{
Lit q = cl.Literals[j];
//ignore UIP
if (q.Var == p)
{
#if (CNSatDebug)
q.Var.Print();
Console.Write(" n(sub) ");
#endif
continue;
}
//ignore sawnvariables and decissionlevel 0
if (!q.Var.Seen && q.Var.DecisionLevel != decisionLevel[0])
{
q.Var.Seen = true;
//if q has been decided in curent level: increase iterations; else add literal to learnt clause
if (q.Var.DecisionLevel.Level >= (decisionLevel[decisionLevel.Count - 1].Level))
{
pathC++;
#if (CNSatDebug)
q.Var.Print();
Console.Write(" n(curlvl) ");
#endif
}
else
{
#if (CNSatDebug)
q.Var.Print();
Console.Write(" add ");
#endif
learnt.Add(q);
}
}
}
// Select next clause to look at:
//do { if(index<0) {Console.Write("BLA"); return false;} }
while (!decisions[index--].Seen)
{
;
}
p = decisions[index + 1];
confl = p.Reason;
p.Seen = false;
pathC--;
#if (CNSatDebug)
Console.WriteLine();
#endif
} while (pathC > 0);
#if (CNSatDebug)
Console.WriteLine("-------------------");
#endif
//Add UIP
Lit t = new Lit(p, (p.Assignment == Assignment.False) ? Assignment.True : Assignment.False);
learnt.Add(t);
//Store Seen Variables for later reset
List <Lit> SeenList = new List <Lit>(learnt.Literals);
//simplify learnt clause
//Here is still an error!!!!!!!
for (int m = 0; m < learnt.Literals.Count - 1; ++m)
{
Lit l = learnt.Literals[m];
//Ignore Literals without reason
if (l.Var.Reason == null)
{
continue;
}
else
{
//Check whether reason for current literal is already in learnt -> remove l
Clause re = l.Var.Reason;
bool found = false;
foreach (Lit rel in re.Literals)
{
if (!rel.Var.Seen && (rel.Var.DecisionLevel != decisionLevel[0]))
{
found = true;
break;
}
}
if (!found)
{
learnt.Literals.RemoveAt(m--);
}
}
}
//Reset Seen
foreach (Lit l in SeenList)
{
l.Var.Seen = false;
}
#if (CNSatDebug)
Console.WriteLine("\nLearned ");
learnt.Print();
//This Stuff checks whether learnt is already in learntClauses -> throws exception
/* bool blub=false;
* for(int r=0; r<satClauses.Count; r++) {
* bool nof=true;
* if(satClauses[r].Literals.Count != learnt.Literals.Count) continue;
* foreach(Lit l in learnt.Literals) {
* bool foundLit = false;
* foreach(Lit m in satClauses[r].Literals) {
* if(l.Var == (m.Var) && l.Sign == m.Sign) {
* foundLit = true;
* break;
* }
* }
* nof &= foundLit;
*
* if (false == nof) break;
* }
* if(nof) blub=true;
* }
* if(blub) throw new Exception("jbjkjdasklfjklasdkgklsaglajgkl");*/
#endif
//End Learn Clause
//Find backtracklevel:
DecisionLevel db;
int i = 1, maxLitIndex;
Lit changeLit;
if (learnt.Literals.Count == 1)
{
db = this.decisionLevel[0];
}
else
{
db = learnt.Literals[0].Var.DecisionLevel;
maxLitIndex = 0;
//Search newest decission, which affects a literal in learnt.
for (i = 1; i < learnt.Literals.Count - 1; ++i)
{
Lit l = learnt.Literals[i];
if (db.Level < l.Var.DecisionLevel.Level)
{
db = l.Var.DecisionLevel;
maxLitIndex = i;
}
}
changeLit = learnt.Literals[0];
learnt.Literals[0] = learnt.Literals[maxLitIndex];
learnt.Literals[maxLitIndex] = changeLit;
}
#if (CNSatDebug)
Console.WriteLine("Backtracking from " + this.decisionLevel[this.decisionLevel.Count - 1].Level + " to " + db.Level);
#endif
//Backtrack to db
backTrack(db);
//Add learnt clause: Unit Clauses have to be satisfied otherwise: -> UNSAT
bool solvable = this.addSATClause(learnt);
if (!solvable) // TODO can be removed once bugfree
{
Console.WriteLine("Error on insert learned clause");
return(false);
}
/*if(db==DecisionLevel[0] && learnt.Literals.Count>1) {
* Console.WriteLine("Reached decision level 0");
* return false;
* }*/
if (learnt.Literals.Count == 1)
{
//decisions[0].Assignment = learnt.Literals[0].Sign;
learnt.Literals[0].Var.Assignment = learnt.Literals[0].Sign;
learnt.Literals[0].Var.Reason = null;
}
//Switch assignment of UIP to satisfy learnt
if (learnt.Literals.Count > 1)
{
//DecisionLevel d = new DecisionLevel(decisions.Count);
//decisionLevel.Add(d);
//Set Learnt as Reason for UIP
Lit l = learnt.Literals[learnt.Literals.Count - 1];
l.Var.Assignment = l.Sign;
learnt.Satisfied = true;
l.Var.DecisionLevel = this.decisionLevel[this.decisionLevel.Count - 1];
l.Var.Reason = learnt;
decisions.Add(l.Var);
}
#if (CNSatDebug)
this.PrintAssignments();
Console.ReadLine();
#endif
return(true);
}
public void Add(Lit l)
{
literals.Add(l);
}