fixing #1520

Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>

src/util/lp/int_solver.h

@@ -50,7 +50,6 @@ public:
     // main function to check that the solution provided by lar_solver is valid for integral values,
     // or provide a way of how it can be adjusted.
     lia_move check(lar_term& t, mpq& k, explanation& ex, bool & upper);
-    lia_move check_(lar_term& t, mpq& k, explanation& ex, bool & upper);
     bool move_non_basic_column_to_bounds(unsigned j);
     lia_move check_wrapper(lar_term& t, mpq& k, explanation& ex);    
     bool is_base(unsigned j) const;

src/util/lp/lar_solver.cpp

@@ -540,11 +540,13 @@ lp_status lar_solver::maximize_term(unsigned ext_j,
         if (m_int_solver->is_base(j)) {
             if (!remove_from_basis(j)) { // consider a special version of remove_from_basis that would not remove inf_int columns
                 m_mpq_lar_core_solver.m_r_x = backup;
+                term_max = prev_value;
                 return lp_status::FEASIBLE; // it should not happen
             }
         }
         m_int_solver->patch_nbasic_column(j, false);
         if (!column_value_is_integer(j)) {
+            term_max = prev_value;
             m_mpq_lar_core_solver.m_r_x = backup;
             return lp_status::FEASIBLE;
         }

src/util/lp/lar_solver.h

@@ -247,6 +247,8 @@ public:
     void calculate_implied_bounds_for_row(unsigned i, bound_propagator & bp);
 
     unsigned adjust_column_index_to_term_index(unsigned j) const;
+
+    var_index local2external(var_index idx) const { return m_var_register.local_to_external(idx); }
     
     void propagate_bounds_on_a_term(const lar_term& t, bound_propagator & bp, unsigned term_offset);
 

src/util/lp/lia_move.h

@@ -28,4 +28,25 @@ enum class lia_move {
     undef,
     unsat
 };
+inline std::string lia_move_to_string(lia_move m) {
+    switch (m) {
+    case lia_move::sat:
+        return "sat";
+    case lia_move::branch:
+        return "branch";
+    case lia_move::cut:
+        return "cut";
+    case lia_move::conflict:
+        return "conflict";
+    case lia_move::continue_with_check:
+        return "continue_with_check";
+    case lia_move::undef:
+        return "undef";
+    case lia_move::unsat:
+        return "unsat";
+    default:
+        lp_assert(false);
+    };
+    return "strange";
+}
 }

src/util/lp/nra_solver.cpp

@@ -24,11 +24,12 @@ namespace nra {
         lp::lar_solver&      s;
         reslimit&              m_limit;  
         params_ref             m_params; 
-        u_map<polynomial::var> m_lp2nl;  // map from lar_solver variables to nlsat::solver variables
+        u_map<polynomial::var> m_lp2nl;  // map from lar_solver variables to nlsat::solver variables        
         scoped_ptr<nlsat::solver>  m_nlsat;
+        scoped_ptr<scoped_anum>    m_zero;
         vector<mon_eq>         m_monomials;
         unsigned_vector        m_monomials_lim;
-        mutable std::unordered_map<lp::var_index, rational> m_variable_values; // current model
+        mutable std::unordered_map<lp::var_index, rational> m_variable_values; // current model        
 
         imp(lp::lar_solver& s, reslimit& lim, params_ref const& p): 
             s(s), 
@@ -90,6 +91,7 @@ namespace nra {
         lbool check(lp::explanation_t& ex) {
             SASSERT(need_check());
             m_nlsat = alloc(nlsat::solver, m_limit, m_params, false);
+            m_zero = alloc(scoped_anum, am());
             m_lp2nl.reset();
             vector<nlsat::assumption, false> core;
 
@@ -208,12 +210,17 @@ namespace nra {
             if (!m_lp2nl.find(v, r)) {
                 r = m_nlsat->mk_var(is_int(v));
                 m_lp2nl.insert(v, r);
+                TRACE("arith", tout << "v" << v << " := x" << r << "\n";);
             }
             return r;
         }
 
         nlsat::anum const& value(lp::var_index v) const {
-           return m_nlsat->value(m_lp2nl.find(v));
+            polynomial::var pv;
+            if (m_lp2nl.find(v, pv))
+                return m_nlsat->value(pv);
+            else
+                return *m_zero;
         }
 
         nlsat::anum_manager& am() {