do not add row with free basic vars in grobner, more tracing

Signed-off-by: Lev Nachmanson <levnach@hotmail.com>

src/math/lp/lar_core_solver.h

@@ -799,6 +799,11 @@ public:
             ( m_column_types()[j] == column_type::boxed &&
               m_r_solver.m_lower_bounds[j] == m_r_solver.m_upper_bounds[j]);
     }
+
+    bool column_is_free(unsigned j) const {
+        return m_column_types()[j] == column_type::free_column;
+    }
+
     
     const impq & lower_bound(unsigned j) const {
         lp_assert(m_column_types()[j] == column_type::fixed ||

src/math/lp/lar_solver.cpp

@@ -1693,6 +1693,10 @@ bool lar_solver::column_is_fixed(unsigned j) const {
     return m_mpq_lar_core_solver.column_is_fixed(j);
 }
 
+bool lar_solver::column_is_free(unsigned j) const {
+    return m_mpq_lar_core_solver.column_is_free(j);
+}
+
 // below is the initialization functionality of lar_solver
 
 bool lar_solver::strategy_is_undecided() const {

src/math/lp/lar_solver.h

@@ -151,6 +151,7 @@ public:
 
     bool is_term(var_index j) const;
     bool column_is_fixed(unsigned j) const;
+    bool column_is_free(unsigned j) const;
 public:
 
     // init region

src/math/lp/nla_common.cpp

@@ -141,8 +141,10 @@ nex * common::nexvar(const rational & coeff, lpvar j, nex_creator& cn, bool fixe
     for (lpvar k : m.vars()) {
         if (fixed_as_scalars && c().var_is_fixed(k)) {
             auto & b = c().m_lar_solver.get_lower_bound(k).x;
-            if (b.is_zero())
+            if (b.is_zero()) {
+                TRACE("nla_grobner", tout << "[" << k << "] is fixed to zero\n";); 
                 return nullptr;
+            }
             e->coeff() *=  b;
             continue;
         }  

src/math/lp/nla_core.cpp

@@ -641,6 +641,10 @@ bool core:: var_is_fixed_to_val(lpvar j, const rational& v) const {
 bool core:: var_is_fixed(lpvar j) const {
     return m_lar_solver.column_is_fixed(j);
 }
+
+bool core:: var_is_free(lpvar j) const {
+    return m_lar_solver.column_is_free(j);
+}
     
 std::ostream & core::print_ineq(const ineq & in, std::ostream & out) const {
     m_lar_solver.print_term_as_indices(in.m_term, out);

src/math/lp/nla_core.h

@@ -287,6 +287,7 @@ public:
     bool var_is_fixed_to_val(lpvar j, const rational& v) const;
 
     bool var_is_fixed(lpvar j) const;
+    bool var_is_free(lpvar j) const;
         
     bool find_canonical_monic_of_vars(const svector<lpvar>& vars, lpvar & i) const;
     bool is_canonical_monic(lpvar) const;

src/math/lp/nla_grobner.cpp

@@ -34,11 +34,19 @@ bool nla_grobner::internalize_gb_eq(equation* ) {
 
 void nla_grobner::add_var_and_its_factors_to_q_and_collect_new_rows(lpvar j, std::queue<lpvar> & q) {
     SASSERT(!c().active_var_set_contains(j));
+    TRACE("grobner", tout << "j = " << j << ", "; c().print_var(j, tout) << "\n";);
     const auto& matrix = c().m_lar_solver.A_r();
     c().insert_to_active_var_set(j);
+    const auto & core_slv = c().m_lar_solver.m_mpq_lar_core_solver;
     for (auto & s : matrix.m_columns[j]) {
         unsigned row = s.var();
         if (m_rows.contains(row)) continue;
+        lpvar basic_in_row = core_slv.m_r_basis[row];
+        if (c().var_is_free(basic_in_row)) {
+            TRACE("grobner", tout << "ignore the row " << row << " with the free basic var\n";); 
+            continue; // mimic the behavior of the legacy solver
+            
+        }
         m_rows.insert(row);
         for (auto& rc : matrix.m_rows[row]) {
             if (c().active_var_set_contains(rc.var()))
@@ -159,6 +167,7 @@ void nla_grobner::init() {
 
     find_nl_cluster();
     c().clear_and_resize_active_var_set();
+    TRACE("grobner", tout << "m_rows.size() = " << m_rows.size() << "\n";);
     for (unsigned i : m_rows) {
         add_row(i);
     }
@@ -730,7 +739,7 @@ bool nla_grobner::done() const {
         ||
         canceled()
         ||
-        m_reported > 10
+        m_reported > 100000
         ||
         m_conflict) {
         TRACE("grobner", tout << "done()\n";);
@@ -776,7 +785,8 @@ bool nla_grobner::try_to_modify_eqs(ptr_vector<equation>& eqs, unsigned& next_we
 
 
 void nla_grobner::grobner_lemmas() {
-    c().lp_settings().stats().m_grobner_calls++;    
+    c().lp_settings().stats().m_grobner_calls++;
+
     init();
     
     ptr_vector<equation> eqs;