fix divergence reported by Guido Martinez

Author: NikolajBjorner

src/math/lp/emonics.cpp

@@ -611,4 +611,19 @@ void emonics::set_propagated(monic const& m) {
     m_u_f_stack.push(set_unpropagated(*this, m.var()));
 }
 
+void emonics::set_bound_propagated(monic const& m) {
+    struct set_bound_unpropagated : public trail {
+        emonics& em;
+        unsigned var;
+    public:
+        set_bound_unpropagated(emonics& em, unsigned var): em(em), var(var) {}
+        void undo() override {
+            em[var].set_bound_propagated(false);
+        }
+    };
+    SASSERT(!m.is_bound_propagated());
+    (*this)[m.var()].set_bound_propagated(true);
+    m_u_f_stack.push(set_bound_unpropagated(*this, m.var()));
+}
+
 }

src/math/lp/emonics.h

@@ -143,6 +143,7 @@ class emonics {
     void after_merge_eh(unsigned r2, unsigned r1, unsigned v2, unsigned v1) {}
 
     void set_propagated(monic const& m);
+    void set_bound_propagated(monic const& m);
 
     // this method is required by union_find
     trail_stack & get_trail_stack() { return m_u_f_stack; }

src/math/lp/monic.h

@@ -59,6 +59,7 @@ class monic: public mon_eq {
     bool             m_rsign;
     mutable unsigned m_visited;
     bool             m_propagated = false;
+    bool             m_bound_propagated = false;
 public:
     // constructors
     monic(lpvar v, unsigned sz, lpvar const* vs, unsigned idx):  
@@ -77,6 +78,8 @@ class monic: public mon_eq {
     void sort_rvars() { std::sort(m_rvars.begin(), m_rvars.end()); }
     void set_propagated(bool p) { m_propagated = p; }
     bool is_propagated() const { return m_propagated; }
+    void set_bound_propagated(bool p) { m_bound_propagated = p; }
+    bool is_bound_propagated() const { return m_bound_propagated; }
 
     svector<lpvar>::const_iterator begin() const { return vars().begin(); }
     svector<lpvar>::const_iterator end() const { return vars().end(); }

src/math/lp/nla_core.cpp

@@ -1517,6 +1517,9 @@ void core::add_bounds() {
         for (lpvar j : m.vars()) {
             if (!var_is_free(j))
                 continue;
+	    if (m.is_bound_propagated())
+                continue;
+	    m_emons.set_bound_propagated(m);
             // split the free variable (j <= 0, or j > 0), and return
             m_literals.push_back(ineq(j, lp::lconstraint_kind::EQ, rational::zero()));
             TRACE("nla_solver", print_ineq(m_literals.back(), tout) << "\n");