add options to substitute vars in Horner and Grobner

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

src/math/lp/horner.cpp

@@ -78,7 +78,7 @@ bool horner::lemmas_on_row(const T& row) {
 
     SASSERT (row_is_interesting(row));
     c().clear_and_resize_active_var_set();
-    create_sum_from_row(row, cn.get_nex_creator(), m_row_sum, nullptr);
+    create_sum_from_row(row, cn.get_nex_creator(), m_row_sum);
     c().set_active_vars_weights(m_nex_creator); // without this call the comparisons will be incorrect
     nex* e =  m_nex_creator.simplify(m_row_sum.mk());
     TRACE("nla_horner", tout << "e = " << * e << "\n";);

src/math/lp/nla_common.cpp

@@ -123,17 +123,9 @@ unsigned common::random() {
 }
 
 // creates a nex expression for the coeff and var, 
-nex * common::nexvar(const rational & coeff, lpvar j, nex_creator& cn,
+nex * common::nexvar(const rational & coeff, lpvar j, nex_creator& cn) {
-                     u_dependency*& dep,
-                     u_dependency_manager* dep_manager) {
     SASSERT(!coeff.is_zero());
-    unsigned lc, uc;
+    if (c().m_nla_settings.horner_subs_fixed() && c().var_is_fixed(j)) {
-    if (c().var_is_fixed(j)) {
-        if (dep_manager) {
-            c().m_lar_solver.get_bound_constraint_witnesses_for_column(j, lc, uc);
-            dep = dep_manager->mk_join(dep, dep_manager->mk_leaf(lc));
-            dep = dep_manager->mk_join(dep, dep_manager->mk_leaf(uc));
-        }
         return cn.mk_scalar(coeff * c().m_lar_solver.column_lower_bound(j).x);
     }
     if (!c().is_monic_var(j)) {
@@ -144,12 +136,7 @@ nex * common::nexvar(const rational & coeff, lpvar j, nex_creator& cn,
     nex_creator::mul_factory mf(cn);
     mf *= coeff;
     for (lpvar k : m.vars()) {
-        if (c().var_is_fixed(k)) {
+        if (c().m_nla_settings.horner_subs_fixed() && c().var_is_fixed(k)) {
-            if (dep_manager) {
-                c().m_lar_solver.get_bound_constraint_witnesses_for_column(k, lc, uc);
-                dep = dep_manager->mk_join(dep, dep_manager->mk_leaf(lc));
-                dep = dep_manager->mk_join(dep, dep_manager->mk_leaf(uc));
-            }
             mf *= c().m_lar_solver.column_lower_bound(k).x;
         } else {
             c().insert_to_active_var_set(k);
@@ -163,31 +150,20 @@ nex * common::nexvar(const rational & coeff, lpvar j, nex_creator& cn,
 }
 
 
-template <typename T> u_dependency* common::create_sum_from_row(const T& row,
+template <typename T> void common::create_sum_from_row(const T& row,
                                                                 nex_creator& cn,
-                                                                nex_creator::sum_factory& sum,
+                                                                nex_creator::sum_factory& sum
-                                                                u_dependency_manager* dep_manager
                                                                 ) {
 
     TRACE("nla_horner", tout << "row="; m_core->print_row(row, tout) << "\n";);
-    u_dependency * dep = nullptr;
     SASSERT(row.size() > 1);
     sum.reset();
     for (const auto &p : row) {
-        nex* e = nexvar(p.coeff(), p.var(), cn, dep, dep_manager);
+        nex* e = nexvar(p.coeff(), p.var(), cn);
         if (!e)
             continue;
-        unsigned lc, uc;
-        if (dep_manager) {
-            c().m_lar_solver.get_bound_constraint_witnesses_for_column(p.var(), lc, uc);
-            if (lc + 1)
-                dep = dep_manager->mk_join(dep, dep_manager->mk_leaf(lc));
-            if (uc + 1) 
-                dep = dep_manager->mk_join(dep, dep_manager->mk_leaf(uc));                    
-        }
         sum += e;
     }
-    return dep;
 }
 
 template <typename T>
@@ -223,4 +199,4 @@ u_dependency* common::get_fixed_vars_dep_from_row(const T& row, u_dependency_man
 
 
 }
-template u_dependency* nla::common::create_sum_from_row<old_vector<lp::row_cell<rational>, true, unsigned int> >(old_vector<lp::row_cell<rational>, true, unsigned int> const&, nla::nex_creator&, nla::nex_creator::sum_factory&, u_dependency_manager*);  
+template void nla::common::create_sum_from_row<old_vector<lp::row_cell<rational>, true, unsigned int> >(old_vector<lp::row_cell<rational>, true, unsigned int> const&, nla::nex_creator&, nla::nex_creator::sum_factory&);  

src/math/lp/nla_common.h

@@ -116,9 +116,9 @@ struct common {
         typedef lp::constraint_index value;
     };
         
-    nex* nexvar(const rational& coeff, lpvar j, nex_creator&, u_dependency*&, u_dependency_manager*);
+    nex* nexvar(const rational& coeff, lpvar j, nex_creator&);
     template <typename T>
-    u_dependency* create_sum_from_row(const T&, nex_creator&, nex_creator::sum_factory&, u_dependency_manager*);
+    void create_sum_from_row(const T&, nex_creator&, nex_creator::sum_factory&);
     template <typename T>
     u_dependency* get_fixed_vars_dep_from_row(const T&, u_dependency_manager& dep_manager);
 };

src/math/lp/nla_core.cpp

@@ -1545,7 +1545,7 @@ const rational& core::val_of_fixed_var_with_deps(lpvar j, u_dependency*& dep) {
 }
 
 dd::pdd core::pdd_expr(const rational& c, lpvar j, u_dependency*& dep) {
-    if (var_is_fixed(j)) {
+    if (m_nla_settings.grobner_subs_fixed() && var_is_fixed(j)) {
         return m_pdd_manager.mk_val(c * val_of_fixed_var_with_deps(j, dep));
     }
 
@@ -1556,7 +1556,7 @@ dd::pdd core::pdd_expr(const rational& c, lpvar j, u_dependency*& dep) {
     dd::pdd r = m_pdd_manager.mk_val(c);
     const monic& m = emons()[j];
     for (lpvar k : m.vars()) {
-        if (var_is_fixed(k)) {
+        if (m_nla_settings.grobner_subs_fixed() && var_is_fixed(k)) {
             r *= m_pdd_manager.mk_val(val_of_fixed_var_with_deps(k, dep));
         } else {
             r *= m_pdd_manager.mk_var(k);

src/math/lp/nla_params.pyg

@@ -4,11 +4,12 @@ def_module_params('nla',
                    ('order', BOOL, True, 'run order lemmas'),
                    ('tangents', BOOL, True, 'run tangent lemmas'),
                    ('horner', BOOL, True, 'run horner\'s heuristic'),
+                   ('horner_subs_fixed', BOOL, True, 'substitute fixed variables by constants'),
                    ('horner_frequency', UINT, 4, 'horner\'s call frequency'),
                    ('horner_row_length_limit', UINT, 10, 'row is disregarded by the heuristic if its length is longer than the value'),
                    ('grobner', BOOL, True, 'run grobner\'s basis heuristic'),
-                   ('grobner_frequency', UINT, 5, 'grobner\'s call frequency'),
+                   ('grobner_eqs_threshold', UINT, 512, 'grobner\'s maximum number of equalities'),
-                   ('grobner_eqs_threshold', UINT, 512, 'grobner\'s maximum number of equalities')
+                   ('grobner_subs_fixed', BOOL, False, 'substitute fixed variables by constants')
                           ))           
 
 

src/math/lp/nla_settings.h

@@ -27,18 +27,21 @@ class nla_settings {
     // how often to call the horner heuristic
     unsigned m_horner_frequency;
     unsigned m_horner_row_length_limit;
+    bool m_horner_subs_fixed;
     // grobner fields
     bool m_run_grobner;
     unsigned m_grobner_row_length_limit;
-
+    bool m_grobner_subs_fixed;
 public:
     nla_settings() : m_run_order(true),
                      m_run_tangents(true),
                      m_run_horner(true),
                      m_horner_frequency(4),
                      m_horner_row_length_limit(10),
+                     m_horner_subs_fixed(true),
                      m_run_grobner(true),
-                     m_grobner_row_length_limit(50)
+                     m_grobner_row_length_limit(50),
+                     m_grobner_subs_fixed(false)
     {}
     
     bool run_order() const { return m_run_order; }
@@ -54,11 +57,15 @@ public:
     unsigned& horner_frequency() { return m_horner_frequency; }
     unsigned horner_row_length_limit() const { return m_horner_row_length_limit; }
     unsigned& horner_row_length_limit() { return m_horner_row_length_limit; }    
+    bool horner_subs_fixed() const { return m_horner_subs_fixed; }
+    bool& horner_subs_fixed() { return m_horner_subs_fixed; }
 
     bool run_grobner() const { return m_run_grobner; }
     bool& run_grobner() { return m_run_grobner; }
 
     unsigned grobner_row_length_limit() const { return m_grobner_row_length_limit; }
     unsigned& grobner_row_length_limit() { return m_grobner_row_length_limit; }
+    bool grobner_subs_fixed() const { return m_grobner_subs_fixed; }
+    bool& grobner_subs_fixed() { return m_grobner_subs_fixed; }
 };
 }

src/smt/theory_lra.cpp

@@ -450,9 +450,12 @@ class theory_lra::imp {
             m_nla->get_core()->m_nla_settings.run_order() = nla.order();
             m_nla->get_core()->m_nla_settings.run_tangents() = nla.tangents();
             m_nla->get_core()->m_nla_settings.run_horner() = nla.horner();
+            m_nla->get_core()->m_nla_settings.horner_subs_fixed() = nla.horner_subs_fixed();
+            
             m_nla->get_core()->m_nla_settings.horner_frequency() = nla.horner_frequency();
             m_nla->get_core()->m_nla_settings.horner_row_length_limit() = nla.horner_row_length_limit();
             m_nla->get_core()->m_nla_settings.run_grobner() = nla.grobner();
+            m_nla->get_core()->m_nla_settings.grobner_subs_fixed() = nla.grobner_subs_fixed();
         }
     }