diff --git a/gecode/int/branch/cbs.hpp b/gecode/int/branch/cbs.hpp
index 331681d9e2..3071acb6e0 100755
--- a/gecode/int/branch/cbs.hpp
+++ b/gecode/int/branch/cbs.hpp
@@ -147,6 +147,8 @@ namespace Gecode { namespace Int { namespace Branch {
     // Lambda we pass to propagators via solndistrib to query solution densities
     auto SendMarginal = [this](unsigned int prop_id, unsigned int var_id,
                                int val, double dens) {
+        if (!varIdToPos.isIn(var_id)) return;
+
         if (logProp[prop_id].dens < dens) {
           logProp[prop_id].var_id = var_id;
           logProp[prop_id].val = val;
@@ -157,6 +159,11 @@ namespace Gecode { namespace Int { namespace Branch {
     for (auto& kv : logProp)
       kv.second.visited = false;
 
+    // We can change rho's value. Actually, there is no memory exception
+    // with rho = 1. But with other values of rho, there is a memory 
+    // exception for some crossword problems.
+    float rho = 1;
+
     for (Propagators p(home, PropagatorGroup::all); p(); ++p) {
       unsigned int prop_id = p.propagator().id();
       unsigned int domsum;
@@ -181,7 +188,7 @@ namespace Gecode { namespace Int { namespace Branch {
       // If the domain size sum of all variables in the propagator has changed
       // since the last time we called this function, we need to recompute
       // solution densities. Otherwise, we can reuse them.
-      if (logProp[prop_id].domsum != domsum) {
+      if (domsum < rho * logProp[prop_id].domsum || logProp[prop_id].domsum == 0) {
         logProp[prop_id].dens = -1;
         // Solution density computation
         p.propagator().solndistrib(home, SendMarginal);
diff --git a/gecode/int/extensional/compact.hpp b/gecode/int/extensional/compact.hpp
index ae2c619182..62640795e9 100755
--- a/gecode/int/extensional/compact.hpp
+++ b/gecode/int/extensional/compact.hpp
@@ -533,6 +533,79 @@ namespace Gecode { namespace Int { namespace Extensional {
     return sizeof(*this);
   }
 
+#ifdef GECODE_HAS_CBS
+  template<class View, class Table>
+  void
+  void 
+  PosCompact<View,Table>::solndistrib(Space& home,
+                                      Propagator::SendMarginal send) const {
+
+    int minVal = std::numeric_limits<int>::max();
+    int maxVal = std::numeric_limits<int>::min();
+
+    for (Advisors<CTAdvisor> as(c); as(); ++as) {
+      CTAdvisor& a = as.advisor();
+      View x = a.view();
+
+      minVal = std::min(x.min(), minVal);
+      maxVal = std::max(x.max(), maxVal);
+    }
+
+    Region r;
+    unsigned long long int* solCounts = r.alloc<unsigned long long int>(maxVal - minVal + 1);
+
+    for (Advisors<CTAdvisor> as(c); as(); ++as) {
+      CTAdvisor& a = as.advisor();
+      View x = a.view();
+
+      if (x.assigned()) continue;
+
+      // Normalization constant for keeping densities values between 0 and 1
+      double normalization = 0;
+
+      for (ValidSupports vs(*this, a); vs(); ++vs) {
+        assert(vs.val() >= minVal);
+        assert(vs.val() <= maxVal);
+
+        unsigned long long int cbsSupports = table.ones(vs.supports());
+        solCounts[vs.val() - minVal] = cbsSupports;
+        normalization += cbsSupports;
+      }
+
+      // Because we approximate the permanent of each value for the variable, we
+      // assign densities in a separate loop where we normalize solution densities.
+      for (ValidSupports vs(*this, a); vs(); ++vs) {
+          send(this->id(),
+               x.id(),
+               x.baseval(vs.val()),
+               solCounts[vs.val() - minVal] / normalization);
+      }
+    } 
+
+    r.free();
+  }
+
+  template<class View, class Table>
+  void
+  PosCompact<View,Table>::domainsizesum(Propagator::InDecision in,
+                                        unsigned int& size,
+                                        unsigned int& size_b) const {
+    size   = 0;
+    size_b = 0;
+
+    for (Advisors<CTAdvisor> as(c); as(); ++as) {
+      CTAdvisor& a = as.advisor();
+      View x = a.view();
+
+      if (!x.assigned()) {
+        size += x.size();
+        if (in(x.id()))
+          size_b += x.size();
+      }
+    }
+  }
+#endif
+
   template<class View, class Table>
   void
   PosCompact<View,Table>::reschedule(Space& home) {