Check if derivative is constant in validation of assumption

src/storm-pars/analysis/AssumptionChecker.cpp

@@ -171,6 +171,7 @@ namespace storm {
                 typename storm::storage::SparseMatrix<ValueType>::iterator state1succ2,
                 typename storm::storage::SparseMatrix<ValueType>::iterator state2succ1,
                 typename storm::storage::SparseMatrix<ValueType>::iterator state2succ2) {
+            bool result = true;
 
             ValueType prob;
             auto comp = lattice->compare(state1succ1->getColumn(), state1succ2->getColumn());
@@ -185,14 +186,17 @@ namespace storm {
             std::map<storm::RationalFunctionVariable, typename ValueType::CoeffType> substitutions;
             for (auto var : vars) {
                 auto derivative = prob.derivative(var);
-                assert(derivative.isConstant());
+                if(derivative.isConstant()) {
                     if (derivative.constantPart() >= 0) {
                         substitutions[var] = 0;
                     } else if (derivative.constantPart() <= 0) {
                         substitutions[var] = 1;
                     }
+                } else {
+                    result = false;
+                }
             }
-            return prob.evaluate(substitutions) >= 0;
+            return result && prob.evaluate(substitutions) >= 0;
         }
 
         template <typename ValueType>