We need to reset local conflicts

src/smt/seq/seq_nielsen.cpp

@@ -1315,6 +1315,11 @@ namespace seq {
         SASSERT(depth <= cur_path.size());
         m_stats.m_max_depth = std::max(m_stats.m_max_depth, depth);
 
+        if (node->is_general_conflict()) {
+            ++m_stats.m_num_simplify_conflict;
+            return search_result::unsat;
+        }
+
         // check for external cancellation (timeout, user interrupt)
         if (!m.inc())
             return search_result::unknown;
@@ -1336,10 +1341,18 @@ namespace seq {
             return search_result::unknown;
         }
         node->set_eval_idx(m_run_idx);
+        SASSERT(!node->is_general_conflict());
+        node->clear_local_conflict(); // clear local conflicts from previous runs
+
         // we might need to tell the SAT solver about the new integer inequalities
         // that might have been added by an extension step
         assert_node_new_int_constraints(node);
 
+        if (node->is_currently_conflict()) {
+            ++m_stats.m_num_simplify_conflict;
+            return search_result::unsat;
+        }
+
         // simplify constraints (idempotent after first call)
         const simplify_result sr = node->simplify_and_init(cur_path);
 

src/smt/seq/seq_nielsen.h

@@ -611,6 +611,13 @@ namespace seq {
                 (reason() != backtrack_reason::unevaluated && m_is_extended);
         }
 
+        void clear_local_conflict() {
+            SASSERT(!is_general_conflict());
+            m_reason = backtrack_reason::unevaluated;
+            m_conflict_internal = nullptr;
+            m_conflict_external_literal = sat::null_literal;
+        }
+
         backtrack_reason reason() const { return m_reason; }
 
         void set_child_conflict() {

src/smt/seq/seq_nielsen_pp.cpp

@@ -589,10 +589,10 @@ namespace seq {
                 out << ", color=green";
             else if (n->is_general_conflict())
                 out << ", color=darkred";
-            else if (n->eval_idx() != m_run_idx)  // inactive, not visited this run
-                out << ", color=blue";
             else if (n->is_currently_conflict())
                 out << ", color=red";
+            else if (n->eval_idx() != m_run_idx)  // inactive, not visited this run
+                out << ", color=blue";
 
             out << "];\n";
         }