na

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

src/math/lp/nla_basics_lemmas.cpp

@@ -207,11 +207,11 @@ void basics::negate_strict_sign(new_lemma& lemma, lpvar j) {
     } 
     else {  // val(j).is_zero()
         if (c().has_lower_bound(j) && c().get_lower_bound(j) >= rational(0)) {
-            c().explain_existing_lower_bound(lemma, j);
+            lemma.explain_existing_lower_bound(j);
             lemma |= ineq(j, llc::GT, 0);
         } else {
             SASSERT(c().has_upper_bound(j) && c().get_upper_bound(j) <= rational(0));
-            c().explain_existing_upper_bound(lemma, j);
+            lemma.explain_existing_upper_bound(j);
             lemma |= ineq(j, llc::LT, 0);
         }
     }
@@ -302,7 +302,7 @@ bool basics::basic_lemma_for_mon_non_zero_derived(const monic& rm, const factori
             continue;
         new_lemma lemma(c(), "x = 0 or y = 0 -> xy = 0");
         lemma.explain_fixed(var(fc));
-        c().explain_var_separated_from_zero(lemma, var(rm));
+        lemma.explain_var_separated_from_zero(var(rm));
         lemma &= rm;
         lemma &= f;
         return true;
@@ -328,7 +328,7 @@ bool basics::basic_lemma_for_mon_neutral_derived(const monic& rm, const factoriz
         return false;
     }
     bool mon_var_is_sep_from_zero =  c().var_is_separated_from_zero(mon_var);
-    lpvar jl = null_lpvar, not_one_j = null_lpvar;
+    lpvar u = null_lpvar, v = null_lpvar;
     bool all_int = true;
     for (auto fc : f) {
         lpvar j = var(fc);
@@ -336,31 +336,22 @@ bool basics::basic_lemma_for_mon_neutral_derived(const monic& rm, const factoriz
         if (j == null_lpvar && abs(val(j)) == abs_mv && 
             c().vars_are_equiv(j, mon_var) &&
             (mon_var_is_sep_from_zero ||  c().var_is_separated_from_zero(j))) 
-            jl = j;
+            u = j;
-        else if (j == jl)
-            return false;
         else if (abs(val(j)) != rational(1)) 
-            not_one_j = j;
+            v = j;
     }
-    if (jl == null_lpvar || not_one_j == null_lpvar)
+    if (u == null_lpvar || v == null_lpvar)
         return false;    
     if (!all_int && f.size() > 2)
         return false;
 
+    //    (mon_var != 0 || u != 0) & mon_var = +/- u =>
+    //    v = 1 or v = -1
     new_lemma lemma(c(), "|xa| = |x| & x != 0 -> |a| = 1");
-    // mon_var = 0
+    lemma.explain_var_separated_from_zero(mon_var_is_sep_from_zero ? mon_var : u);    
-    if (mon_var_is_sep_from_zero)
+    lemma.explain_equiv(mon_var, u);        
-        c().explain_var_separated_from_zero(lemma, mon_var);
+    lemma |= ineq(v, llc::EQ, 1);        
-    else
+    lemma |= ineq(v, llc::EQ, -1);
-        c().explain_var_separated_from_zero(lemma, jl);
-    
-    lemma.explain_equiv(mon_var, jl);
-        
-    // not_one_j = 1
-    lemma |= ineq(not_one_j, llc::EQ, 1);
-        
-    // not_one_j = -1
-    lemma |= ineq(not_one_j, llc::EQ, -1);
     lemma &= rm;
     lemma &= f;
     return true;
@@ -422,9 +413,6 @@ NSB review:
 
    sign_m*m < 0 or f_j = 0 or \/_{i != j} sign_m*m >= sign_i*f_i
 
-- or even, without reference to factor index:
-   sign_m*m < 0 or \/_i sign_m*m >= sign_i*f_i
-
 */
 void basics::generate_pl_on_mon(const monic& m, unsigned factor_index) {
     SASSERT(!mon_has_real(m));
@@ -529,7 +517,7 @@ void basics::basic_lemma_for_mon_zero_model_based(const monic& rm, const factori
     } else {
         lemma |= ineq(var(rm), llc::NE, 0);
         for (auto j : f) {
-            c().explain_separation_from_zero(lemma, var(j));
+            lemma.explain_separation_from_zero(var(j));
         }            
     }
     lemma &= f;
@@ -601,8 +589,8 @@ bool basics::basic_lemma_for_mon_neutral_from_factors_to_monic_model_based_fm(co
        
     new_lemma lemma(c(), __FUNCTION__);
     for (auto j : m.vars()) {
-        if (not_one == j) continue;
+        if (not_one != j) 
-        lemma |= ineq(j, llc::NE, val(j));
+            lemma |= ineq(j, llc::NE, val(j));
     }
 
     if (not_one == null_lpvar) 
@@ -613,7 +601,7 @@ bool basics::basic_lemma_for_mon_neutral_from_factors_to_monic_model_based_fm(co
 }
 
 // use the fact that
-// |xabc| = |x| and x != 0 -> |a| = |b| = |c| = 1 
+// |uvw| = |u| and uvw != 0 -> |v| = 1 
 bool basics::basic_lemma_for_mon_neutral_monic_to_factor_model_based(const monic& rm, const factorization& f) {
     lpvar mon_var = c().emons()[rm.var()].var();
     TRACE("nla_solver_bl", c().trace_print_monic_and_factorization(rm, f, tout); tout << "\nmon_var = " << mon_var << "\n";);
@@ -624,36 +612,32 @@ bool basics::basic_lemma_for_mon_neutral_monic_to_factor_model_based(const monic
     if (abs_mv == rational::zero()) {
         return false;
     }
-    lpvar jl = null_lpvar, not_one_j = null_lpvar;
+    lpvar u = null_lpvar, v = null_lpvar;
     bool all_int = true;
     for (auto fc : f) {
         lpvar j = var(fc);
         all_int &= c().var_is_int(j);        
         if (j == null_lpvar && abs(val(fc)) == abs_mv) 
-            jl = j;
+            u = j;
-        else if (j == jl)
-            return false;
         else if (abs(val(fc)) != rational(1)) 
-            not_one_j = j;
+            v = j;
     }
-    if (jl == null_lpvar || not_one_j == null_lpvar)
+    if (u == null_lpvar || v == null_lpvar)
         return false;    
     if (!all_int && f.size() > 2)
         return false;
 
-    new_lemma lemma(c(), __FUNCTION__);
     // mon_var = 0
-    lemma |= ineq(mon_var, llc::EQ, 0);
+    // abs(u) != abs(mon_var)    
-        
+    // v = 1
-    // negate abs(jl) == abs()    
+    // v = -1
-    lemma |= ineq(term(jl, rational(val(jl) == -val(mon_var) ? 1 : -1), mon_var), llc::NE, 0);
 
-    // not_one_j = 1
+    new_lemma lemma(c(), __FUNCTION__);
-    lemma |= ineq(not_one_j, llc::EQ, 1);
+    lemma |= ineq(mon_var, llc::EQ, 0);        
-        
+    lemma |= ineq(term(u, rational(val(u) == -val(mon_var) ? 1 : -1), mon_var), llc::NE, 0);
-    // not_one_j = -1
+    lemma |= ineq(v, llc::EQ, 1);        
-    lemma |= ineq(not_one_j, llc::EQ, -1);
+    lemma |= ineq(v, llc::EQ, -1);
-    lemma &= rm;
+    lemma &= rm; // NSB review: is this dependency required?
     lemma &= f;
 
     return true;
@@ -695,7 +679,7 @@ bool basics::basic_lemma_for_mon_neutral_from_factors_to_monic_model_based(const
         }
             
         if (v == -rational(1)) { 
-            sign = - sign;
+            sign = -sign;
             continue;
         } 
             

src/math/lp/nla_core.cpp

@@ -625,24 +625,6 @@ bool core::is_canonical_monic(lpvar j) const {
 }
 
 
-void core::explain_existing_lower_bound(new_lemma& lemma, lpvar j) {
-    SASSERT(has_lower_bound(j));
-    lemma &= m_lar_solver.get_column_lower_bound_witness(j);
-}
-
-void core::explain_existing_upper_bound(new_lemma& lemma, lpvar j) {
-    SASSERT(has_upper_bound(j));
-    lemma &= m_lar_solver.get_column_upper_bound_witness(j);
-}
-    
-void core::explain_separation_from_zero(new_lemma& lemma, lpvar j) {
-    SASSERT(!val(j).is_zero());
-    if (val(j).is_pos())
-        explain_existing_lower_bound(lemma, j);
-    else
-        explain_existing_upper_bound(lemma, j);
-}
-
 void core::trace_print_monic_and_factorization(const monic& rm, const factorization& f, std::ostream& out) const {
     out << "rooted vars: ";
     print_product(rm.rvars(), out) << "\n";
@@ -651,14 +633,6 @@ void core::trace_print_monic_and_factorization(const monic& rm, const factorizat
     print_factorization(f, out << "fact: ") << "\n";
 }
 
-void core::explain_var_separated_from_zero(new_lemma& lemma, lpvar j) {
-    SASSERT(var_is_separated_from_zero(j));
-    if (m_lar_solver.column_has_upper_bound(j) && (m_lar_solver.get_upper_bound(j)< lp::zero_of_type<lp::impq>())) 
-        lemma &= m_lar_solver.get_column_upper_bound_witness(j);
-    else 
-        lemma &= m_lar_solver.get_column_lower_bound_witness(j);
-}
-
 
 bool core::var_has_positive_lower_bound(lpvar j) const {
     return m_lar_solver.column_has_lower_bound(j) && m_lar_solver.get_lower_bound(j) > lp::zero_of_type<lp::impq>();
@@ -1187,6 +1161,38 @@ new_lemma& new_lemma::explain_equiv(lpvar a, lpvar b) {
     return *this;
 }
 
+new_lemma& new_lemma::explain_var_separated_from_zero(lpvar j) {
+    SASSERT(c.var_is_separated_from_zero(j));
+    if (c.m_lar_solver.column_has_upper_bound(j) && 
+        (c.m_lar_solver.get_upper_bound(j)< lp::zero_of_type<lp::impq>())) 
+        *this &= c.m_lar_solver.get_column_upper_bound_witness(j);
+    else 
+        *this &= c.m_lar_solver.get_column_lower_bound_witness(j);
+    return *this;
+}
+
+new_lemma& new_lemma::explain_existing_lower_bound(lpvar j) {
+    SASSERT(c.has_lower_bound(j));
+    *this &= c.m_lar_solver.get_column_lower_bound_witness(j);
+    return *this;
+}
+
+new_lemma& new_lemma::explain_existing_upper_bound(lpvar j) {
+    SASSERT(c.has_upper_bound(j));
+    *this &= c.m_lar_solver.get_column_upper_bound_witness(j);
+    return *this;
+}
+    
+new_lemma& new_lemma::explain_separation_from_zero(lpvar j) {
+    SASSERT(!c.val(j).is_zero());
+    if (c.val(j).is_pos())
+        explain_existing_lower_bound(j);
+    else
+        explain_existing_upper_bound(j);
+    return *this;
+}
+
+
 
 std::ostream& new_lemma::display(std::ostream & out) const {
     auto const& lemma = current();

src/math/lp/nla_core.h

@@ -105,6 +105,11 @@ public:
     new_lemma& operator|=(ineq const& i);
     new_lemma& explain_fixed(lpvar j);
     new_lemma& explain_equiv(lpvar u, lpvar v);
+    new_lemma& explain_var_separated_from_zero(lpvar j);
+    new_lemma& explain_existing_lower_bound(lpvar j);
+    new_lemma& explain_existing_upper_bound(lpvar j);    
+    new_lemma& explain_separation_from_zero(lpvar j);
+
     unsigned num_ineqs() const { return current().ineqs().size(); }
 };
 
@@ -245,13 +250,7 @@ public:
     
     // return true iff the monic value is equal to the product of the values of the factors
     bool check_monic(const monic& m) const;
-    
+   
-    // NSB review: these should really be methods on new_lemma
-    void explain_existing_lower_bound(new_lemma& lemma, lpvar j);
-    void explain_existing_upper_bound(new_lemma& lemma, lpvar j);    
-    void explain_separation_from_zero(new_lemma& lemma, lpvar j);
-    void explain_var_separated_from_zero(new_lemma& lemma, lpvar j);
-
 
     std::ostream & print_ineq(const ineq & in, std::ostream & out) const;
     std::ostream & print_var(lpvar j, std::ostream & out) const;