diff --git a/src/sat/sat_clause.h b/src/sat/sat_clause.h
index 7bacf0777..1477cc6e3 100644
--- a/src/sat/sat_clause.h
+++ b/src/sat/sat_clause.h
@@ -65,8 +65,7 @@ namespace sat {
         literal & operator[](unsigned idx) { SASSERT(idx < m_size); return m_lits[idx]; }
         literal const & operator[](unsigned idx) const { SASSERT(idx < m_size); return m_lits[idx]; }
         bool is_learned() const { return m_learned; }
-        void set_learned() { SASSERT(!is_learned()); m_learned = true; }
-        void unset_learned() { SASSERT(is_learned()); m_learned = false; }
+        void set_learned(bool l) { SASSERT(is_learned() != l); m_learned = l; }
         void shrink(unsigned num_lits) { SASSERT(num_lits <= m_size); if (num_lits < m_size) { m_size = num_lits; mark_strengthened(); } }
         bool strengthened() const { return m_strengthened; }
         void mark_strengthened() { m_strengthened = true; update_approx(); }
diff --git a/src/sat/sat_simplifier.cpp b/src/sat/sat_simplifier.cpp
index 106cc791e..577badbc8 100644
--- a/src/sat/sat_simplifier.cpp
+++ b/src/sat/sat_simplifier.cpp
@@ -151,7 +151,7 @@ namespace sat {
     inline void simplifier::block_clause(clause & c) {
         if (m_retain_blocked_clauses) {
             m_need_cleanup = true;
-            c.set_learned();
+            s.set_learned(c, true);
             m_use_list.block(c);
         }
         else {
@@ -161,7 +161,7 @@ namespace sat {
     }
 
     inline void simplifier::unblock_clause(clause & c) {
-        c.unset_learned();
+        s.set_learned(c, false);
         m_use_list.unblock(c);
     }
 
@@ -499,7 +499,7 @@ namespace sat {
             if (!c2.was_removed() && *l_it == null_literal) {
                 // c2 was subsumed
                 if (c1.is_learned() && !c2.is_learned())
-                    c1.unset_learned();
+                    s.set_learned(c1, false);
                 TRACE("subsumption", tout << c1 << " subsumed " << c2 << "\n";);
                 remove_clause(c2);
                 m_num_subsumed++;
@@ -599,7 +599,7 @@ namespace sat {
             clause & c2 = *cp;
             // c2 was subsumed
             if (c1.is_learned() && !c2.is_learned())
-                c1.unset_learned();
+                s.set_learned(c1, false);
             TRACE("subsumption", tout << c1 << " subsumed " << c2 << "\n";);
             remove_clause(c2);
             m_num_subsumed++;
@@ -759,7 +759,7 @@ namespace sat {
                             SASSERT(wlist[j] == w);
                             TRACE("set_not_learned_bug",
                                   tout << "marking as not learned: " << l2 << " " << wlist[j].is_learned() << "\n";);
-                            wlist[j].set_not_learned();
+                            wlist[j].set_learned(false);
                             mark_as_not_learned_core(get_wlist(~l2), l);
                         }
                         if (s.inconsistent())
@@ -776,7 +776,7 @@ namespace sat {
     void simplifier::mark_as_not_learned_core(watch_list & wlist, literal l2) {
         for (watched & w : wlist) {
             if (w.is_binary_clause() && w.get_literal() == l2 && w.is_learned()) {
-                w.set_not_learned();
+                w.set_learned(false);
                 return;
             }
         }
@@ -1793,7 +1793,7 @@ namespace sat {
         w = find_binary_watch(wlist1, l2);
         if (w) {
             if (w->is_learned())
-                w->set_not_learned();
+                w->set_learned(false);
         }
         else {
             wlist1.push_back(watched(l2, false));
@@ -1802,7 +1802,7 @@ namespace sat {
         w = find_binary_watch(wlist2, l1);
         if (w) {
             if (w->is_learned())
-                w->set_not_learned();
+                w->set_learned(false);
         }
         else {
             wlist2.push_back(watched(l1, false));
diff --git a/src/sat/sat_solver.cpp b/src/sat/sat_solver.cpp
index 0c2d34dac..d21e773f3 100644
--- a/src/sat/sat_solver.cpp
+++ b/src/sat/sat_solver.cpp
@@ -336,13 +336,13 @@ namespace sat {
         watched* w0 = find_binary_watch(get_wlist(~l1), l2);
         if (w0) {
             if (w0->is_learned() && !learned) {
-                w0->set_not_learned();
+                w0->set_learned(false);
             }            
             w0 = find_binary_watch(get_wlist(~l2), l1);
         }
         if (w0) {
             if (w0->is_learned() && !learned) {
-                w0->set_not_learned();
+                w0->set_learned(false);
             }            
             return;
         }
@@ -481,6 +481,19 @@ namespace sat {
             reinit = attach_nary_clause(c);
     }
 
+    void solver::set_learned(clause& c, bool learned) {
+        if (c.is_learned() == learned) 
+            return;
+
+        if (c.size() == 3) {
+            set_ternary_learned(get_wlist(~c[0]), c[1], c[2], learned);
+            set_ternary_learned(get_wlist(~c[1]), c[0], c[2], learned);
+            set_ternary_learned(get_wlist(~c[2]), c[0], c[1], learned);
+        }
+        c.set_learned(learned);
+    }
+
+
     /**
        \brief Select a watch literal starting the search at the given position.
        This method is only used for clauses created during the search.
diff --git a/src/sat/sat_solver.h b/src/sat/sat_solver.h
index 8b97dc7ea..0370d634d 100644
--- a/src/sat/sat_solver.h
+++ b/src/sat/sat_solver.h
@@ -233,6 +233,7 @@ namespace sat {
         bool attach_nary_clause(clause & c);
         void attach_clause(clause & c, bool & reinit);
         void attach_clause(clause & c) { bool reinit; attach_clause(c, reinit); }
+        void set_learned(clause& c, bool learned);
         class scoped_disable_checkpoint {
             solver& s;
         public:
@@ -611,7 +612,7 @@ namespace sat {
         clause * const * end_learned() const { return m_learned.end(); }
         clause_vector const& learned() const { return m_learned; }
         clause_vector const& clauses() const { return m_clauses; }
-        void collect_bin_clauses(svector<bin_clause> & r, bool learned, bool learned_only = false) const;
+        void collect_bin_clauses(svector<bin_clause> & r, bool learned, bool learned_only = false) const;        
 
         // -----------------------
         //
diff --git a/src/sat/sat_watched.cpp b/src/sat/sat_watched.cpp
index 1a0880282..d7c6520bd 100644
--- a/src/sat/sat_watched.cpp
+++ b/src/sat/sat_watched.cpp
@@ -52,7 +52,7 @@ namespace sat {
         }
         return nullptr;
     }
-
+    
     void erase_binary_watch(watch_list& wlist, literal l) {
         watch_list::iterator it = wlist.begin(), end = wlist.end();
         watch_list::iterator it2 = it;
@@ -70,6 +70,30 @@ namespace sat {
         VERIFY(found);
     }
 
+    void erase_ternary_watch(watch_list& wlist, literal l1, literal l2) {
+        watch_list::iterator it = wlist.begin(), end = wlist.end();
+        watch_list::iterator it2 = it;
+        bool found = false;
+        for (; it != end; ++it) {
+            if (it->is_ternary_clause() && it->get_literal1() == l1 && it->get_literal2() == l2) {
+                found = true;
+                continue;
+            }
+            *it2 = *it;
+            ++it2;        
+        }
+        wlist.set_end(it2);
+        VERIFY(found);
+    }
+
+    void set_ternary_learned(watch_list& wlist, literal l1, literal l2, bool learned) {
+        for (watched& w : wlist) {
+            if (w.is_ternary_clause() && w.get_literal1() == l1 && w.get_literal2() == l2) {
+                w.set_learned(learned);
+            }
+        }
+    }
+
     void conflict_cleanup(watch_list::iterator it, watch_list::iterator it2, watch_list& wlist) {
         watch_list::iterator end = wlist.end();
         for (; it != end; ++it, ++it2) 
diff --git a/src/sat/sat_watched.h b/src/sat/sat_watched.h
index 88b6f3e51..8979405ae 100644
--- a/src/sat/sat_watched.h
+++ b/src/sat/sat_watched.h
@@ -33,7 +33,7 @@ namespace sat {
 
        For binary clauses: we use a bit to store whether the binary clause was learned or not.
        
-       Remark: there is not Clause object for binary clauses.
+       Remark: there are no clause objects for binary clauses.
     */
     class watched {
     public:
@@ -87,13 +87,12 @@ namespace sat {
         bool is_binary_clause() const { return get_kind() == BINARY; }
         literal get_literal() const { SASSERT(is_binary_clause()); return to_literal(static_cast<unsigned>(m_val1)); }
         void set_literal(literal l) { SASSERT(is_binary_clause()); m_val1 = l.to_uint(); }
-        bool is_learned() const { SASSERT(is_binary_clause()); return (m_val2 >> 2) == 1; }
+        bool is_learned() const { SASSERT(is_binary_clause() || is_ternary_clause()); return ((m_val2 >> 2) & 1) == 1; }
 
         bool is_binary_learned_clause() const { return is_binary_clause() && is_learned(); }
         bool is_binary_non_learned_clause() const { return is_binary_clause() && !is_learned(); }
 
-        void set_not_learned() { SASSERT(is_learned()); m_val2 &= 0x3; SASSERT(!is_learned()); }
-        void set_learned() { SASSERT(!is_learned()); m_val2 |= 0x4; SASSERT(is_learned()); }
+        void set_learned(bool l) { SASSERT(is_learned() != l); if (l) m_val2 |= 4; else m_val2 &= 3; SASSERT(is_learned() == l); }
                 
         bool is_ternary_clause() const { return get_kind() == TERNARY; }
         literal get_literal1() const { SASSERT(is_ternary_clause()); return to_literal(static_cast<unsigned>(m_val1)); }
@@ -136,7 +135,8 @@ namespace sat {
     watched* find_binary_watch(watch_list & wlist, literal l);
     watched const* find_binary_watch(watch_list const & wlist, literal l);
     bool erase_clause_watch(watch_list & wlist, clause_offset c);
-    inline void erase_ternary_watch(watch_list & wlist, literal l1, literal l2) { wlist.erase(watched(l1, l2, true)); wlist.erase(watched(l1, l2, false)); }
+    void erase_ternary_watch(watch_list & wlist, literal l1, literal l2);
+    void set_ternary_learned(watch_list& wlist, literal l1, literal l2, bool learned);
 
     class clause_allocator;
     std::ostream& display_watch_list(std::ostream & out, clause_allocator const & ca, watch_list const & wlist);