use logarithms to calculate the cost of each fove operator

packages/CLPBN/clpbn/bp/FoveSolver.cpp

@@ -44,8 +44,8 @@ LiftedOperator::printValidOps (
 
 
 
-unsigned
+double
-SumOutOperator::getCost (void)
+SumOutOperator::getLogCost (void)
 {
   TinySet<unsigned> groupSet;
   ParfactorList::const_iterator pfIter = pfList_.begin();
@@ -56,7 +56,7 @@ SumOutOperator::getCost (void)
     }
     ++ pfIter;
   }
-  unsigned cost = 1;
+  double cost = 1.0;
   for (unsigned i = 0; i < groupSet.size(); i++) {
     pfIter = pfList_.begin();
     while (pfIter != pfList_.end()) {
@@ -68,7 +68,7 @@ SumOutOperator::getCost (void)
       ++ pfIter;
     }
   }
-  return cost;
+  return std::log (cost);
 }
 
 
@@ -143,7 +143,7 @@ SumOutOperator::toString (void)
   TupleSet tupleSet = (*pfIters[0])->constr()->tupleSet (f.logVars());
   ss << "sum out " << f.functor() << "/" << f.arity();
   ss << "|" << tupleSet << " (group " << group_ << ")";
-  ss << " [cost=" << getCost() << "]" << endl;
+  ss << " [cost=" << getLogCost() << "]" << endl;
   return ss.str();
 }
 
@@ -228,10 +228,10 @@ SumOutOperator::isToEliminate (
 
 
 
-unsigned
+double
-CountingOperator::getCost (void)
+CountingOperator::getLogCost (void)
 {
-  unsigned cost = 0;
+  double cost = 0.0;
   int fIdx = (*pfIter_)->indexOfLogVar (X_);
   unsigned range = (*pfIter_)->range (fIdx);
   unsigned size  = (*pfIter_)->size() / range;
@@ -240,7 +240,7 @@ CountingOperator::getCost (void)
   for (unsigned i = 0; i < counts.size(); i++) {
     cost += size * HistogramSet::nrHistograms (counts[i], range);
   }
-  return cost;
+  return std::log (cost);
 }
 
 
@@ -295,7 +295,7 @@ CountingOperator::toString (void)
   stringstream ss;
   ss << "count convert " << X_ << " in " ;
   ss << (*pfIter_)->getLabel();
-  ss << " [cost=" << getCost() << "]" << endl;
+  ss << " [cost=" << getLogCost() << "]" << endl;
   Parfactors pfs = FoveSolver::countNormalize (*pfIter_, X_);
   if ((*pfIter_)->constr()->isCountNormalized (X_) == false) {
     for (unsigned i = 0; i < pfs.size(); i++) {
@@ -334,20 +334,22 @@ CountingOperator::validOp (Parfactor* g, LogVar X)
 
 
 
-unsigned
+double
-GroundOperator::getCost (void)
+GroundOperator::getLogCost (void)
 {
-  unsigned cost = 0;
+  double cost = 0.0;
   bool isCountingLv = (*pfIter_)->countedLogVars().contains (X_);
   if (isCountingLv) {
     int fIdx = (*pfIter_)->indexOfLogVar (X_);
     unsigned currSize  = (*pfIter_)->size();
     unsigned nrHists   = (*pfIter_)->range (fIdx);
-    unsigned range     = (*pfIter_)->argument (fIdx).range();
     unsigned nrSymbols = (*pfIter_)->constr()->getConditionalCount (X_);
-    cost = (currSize / nrHists) * (std::pow (range, nrSymbols));
+    unsigned range     = (*pfIter_)->argument (fIdx).range();
+    double power = std::log (range) * nrSymbols;
+    cost = std::log (currSize / nrHists) + power;
   } else {
-    cost = (*pfIter_)->constr()->nrSymbols (X_) * (*pfIter_)->size();
+    unsigned currSize  = (*pfIter_)->size();
+    cost = std::log ((*pfIter_)->constr()->nrSymbols (X_) * currSize);
   }
   return cost;
 }
@@ -401,7 +403,7 @@ GroundOperator::toString (void)
       ? ss << "full expanding " 
       : ss << "grounding " ;
   ss << X_ << " in " << (*pfIter_)->getLabel();
-  ss << " [cost=" << getCost() << "]" << endl;
+  ss << " [cost=" << getLogCost() << "]" << endl;
   return ss.str();
 }
 
@@ -525,12 +527,12 @@ FoveSolver::runSolver (const Grounds& query)
 LiftedOperator*
 FoveSolver::getBestOperation (const Grounds& query)
 {
-  unsigned bestCost = Util::maxUnsigned();
+  double bestCost = 0.0;
   LiftedOperator* bestOp = 0;
   vector<LiftedOperator*> validOps;
   validOps = LiftedOperator::getValidOps (pfList_, query);
   for (unsigned i = 0; i < validOps.size(); i++) {
-    unsigned cost = validOps[i]->getCost();
+    double cost = validOps[i]->getLogCost();
     if ((bestOp == 0) || (cost < bestCost)) {
       bestOp   = validOps[i];
       bestCost = cost;

packages/CLPBN/clpbn/bp/FoveSolver.h

@@ -8,7 +8,7 @@
 class LiftedOperator
 {
   public:
-    virtual unsigned getCost (void) = 0;
+    virtual double getLogCost (void) = 0;
 
     virtual void apply (void) = 0;
 
@@ -28,7 +28,7 @@ class SumOutOperator : public LiftedOperator
     SumOutOperator (unsigned group, ParfactorList& pfList) 
         : group_(group), pfList_(pfList) { }
 
-    unsigned getCost (void);
+    double getLogCost (void);
 
     void apply (void);
 
@@ -60,7 +60,7 @@ class CountingOperator : public LiftedOperator
         ParfactorList& pfList)
         : pfIter_(pfIter), X_(X), pfList_(pfList) { }
 
-    unsigned getCost (void);
+    double getLogCost (void);
 
     void apply (void);
 
@@ -87,7 +87,7 @@ class GroundOperator : public LiftedOperator
         ParfactorList& pfList)
         : pfIter_(pfIter), X_(X), pfList_(pfList) { }
 
-    unsigned getCost (void);
+    double getLogCost (void);
 
     void apply (void);