diff --git a/src/math/lp/int_solver.cpp b/src/math/lp/int_solver.cpp
index 0ab7d1e40..bd1ac5313 100644
--- a/src/math/lp/int_solver.cpp
+++ b/src/math/lp/int_solver.cpp
@@ -31,7 +31,7 @@ namespace lp {
         lra.remove_fixed_vars_from_base();
         lp_assert(lia.is_feasible());
         for (unsigned j : lra.r_basis()) 
-            if (!lra.get_value(j).is_int() && lra.column_is_int(j))
+            if (!lra.get_value(j).is_int() && lra.column_is_int(j)&& !lia.is_fixed(j))
                 patch_basic_column(j);
         if (!lia.has_inf_int()) {
             lia.settings().stats().m_patches_success++;
diff --git a/src/math/lp/lar_solver.cpp b/src/math/lp/lar_solver.cpp
index 1bd55b9bb..5f82516ef 100644
--- a/src/math/lp/lar_solver.cpp
+++ b/src/math/lp/lar_solver.cpp
@@ -22,7 +22,8 @@ namespace lp {
     }
 
     lar_solver::lar_solver() :
-        m_crossed_bounds_column(-1),
+        m_crossed_bounds_column(null_lpvar),
+        m_crossed_bounds_deps(nullptr),
         m_mpq_lar_core_solver(m_settings, *this),
         m_var_register(false),
         m_term_register(true),
@@ -213,17 +214,10 @@ namespace lp {
     }
 
     void lar_solver::fill_explanation_from_crossed_bounds_column(explanation& evidence) const {
-        lp_assert(static_cast<int>(get_column_type(m_crossed_bounds_column)) >= static_cast<int>(column_type::boxed));
-        lp_assert(!column_is_feasible(m_crossed_bounds_column));
-
         // this is the case when the lower bound is in conflict with the upper one
-        const ul_pair& ul = m_columns_to_ul_pairs[m_crossed_bounds_column];
         svector<constraint_index> deps;
-        m_dependencies.linearize(ul.upper_bound_witness(), deps);
-        for (auto d : deps)
-            evidence.add_pair(d, numeric_traits<mpq>::one());
-        deps.reset();
-        m_dependencies.linearize(ul.lower_bound_witness(), deps);
+        SASSERT(m_crossed_bounds_deps != nullptr);
+        m_dependencies.linearize(m_crossed_bounds_deps, deps);
         for (auto d : deps)
             evidence.add_pair(d, -numeric_traits<mpq>::one());
     }
@@ -232,7 +226,8 @@ namespace lp {
         m_simplex_strategy = m_settings.simplex_strategy();
         m_simplex_strategy.push();
         m_columns_to_ul_pairs.push();
-        m_crossed_bounds_column.push();
+        m_crossed_bounds_column = null_lpvar;
+        m_crossed_bounds_deps = nullptr;
         m_mpq_lar_core_solver.push();
         m_term_count = m_terms.size();
         m_term_count.push();
@@ -262,7 +257,8 @@ namespace lp {
 
     void lar_solver::pop(unsigned k) {
         TRACE("lar_solver", tout << "k = " << k << std::endl;);
-        m_crossed_bounds_column.pop(k);
+        m_crossed_bounds_column = null_lpvar;
+        m_crossed_bounds_deps = nullptr;
         unsigned n = m_columns_to_ul_pairs.peek_size(k);
         m_var_register.shrink(n);
         pop_tableau(n);
@@ -1021,7 +1017,7 @@ namespace lp {
 
     void lar_solver::get_infeasibility_explanation(explanation& exp) const {
         exp.clear();
-        if (m_crossed_bounds_column != -1) {
+        if (m_crossed_bounds_column != null_lpvar) {
             fill_explanation_from_crossed_bounds_column(exp);
             return;
         }
@@ -1828,7 +1824,6 @@ namespace lp {
 
         if (is_base(j) && column_is_fixed(j))
             m_fixed_base_var_set.insert(j);
-
         TRACE("lar_solver_feas", tout << "j = " << j << " became " << (this->column_is_feasible(j) ? "feas" : "non-feas") << ", and " << (this->column_is_bounded(j) ? "bounded" : "non-bounded") << std::endl;);    
     }
 
@@ -1924,7 +1919,6 @@ namespace lp {
         }
     }
 
-    // clang-format on
     void lar_solver::update_bound_with_ub_lb(var_index j, lconstraint_kind kind, const mpq& right_side, u_dependency* dep) {
         lp_assert(column_has_lower_bound(j) && column_has_upper_bound(j));
         lp_assert(m_mpq_lar_core_solver.m_column_types[j] == column_type::boxed ||
@@ -1937,12 +1931,14 @@ namespace lp {
             case LE: {
                 auto up = numeric_pair<mpq>(right_side, y_of_bound);
                 if (up < m_mpq_lar_core_solver.m_r_lower_bounds[j]) {
-                    set_infeasible_column(j);
+                    set_infeasible_column_and_witness(j, true, dep);
+                }
+                else {
+                    if (up >= m_mpq_lar_core_solver.m_r_upper_bounds[j]) return;
+                    m_mpq_lar_core_solver.m_r_upper_bounds[j] = up;
+                    set_upper_bound_witness(j, dep);
+                    insert_to_columns_with_changed_bounds(j);
                 }
-                if (up >= m_mpq_lar_core_solver.m_r_upper_bounds[j]) return;
-                m_mpq_lar_core_solver.m_r_upper_bounds[j] = up;
-                set_upper_bound_witness(j, dep);
-                insert_to_columns_with_changed_bounds(j);
                 break;
             }
             case GT:
@@ -1950,25 +1946,33 @@ namespace lp {
             case GE: {
                 auto low = numeric_pair<mpq>(right_side, y_of_bound);
                 if (low > m_mpq_lar_core_solver.m_r_upper_bounds[j]) {
-                    set_infeasible_column(j);
+                    set_infeasible_column_and_witness(j, false, dep);
+                } else {
+                    if (low < m_mpq_lar_core_solver.m_r_lower_bounds[j]) {
+                        return;
+                    }
+                    m_mpq_lar_core_solver.m_r_lower_bounds[j] = low;
+                    set_lower_bound_witness(j, dep);
+                    m_mpq_lar_core_solver.m_column_types[j] = (low == m_mpq_lar_core_solver.m_r_upper_bounds[j] ? column_type::fixed : column_type::boxed);
+                    insert_to_columns_with_changed_bounds(j);
                 }
-                if (low < m_mpq_lar_core_solver.m_r_lower_bounds[j]) {
-                    return;
-                }
-                m_mpq_lar_core_solver.m_r_lower_bounds[j] = low;
-                set_lower_bound_witness(j, dep);
-                m_mpq_lar_core_solver.m_column_types[j] = (low == m_mpq_lar_core_solver.m_r_upper_bounds[j] ? column_type::fixed : column_type::boxed);
-                insert_to_columns_with_changed_bounds(j);
                 break;
+                
             } 
             case EQ: {
                 auto v = numeric_pair<mpq>(right_side, zero_of_type<mpq>());
-                if (v > m_mpq_lar_core_solver.m_r_upper_bounds[j] || v < m_mpq_lar_core_solver.m_r_lower_bounds[j]) {
-                    set_infeasible_column(j);
+                if (v > m_mpq_lar_core_solver.m_r_upper_bounds[j]){
+                    set_infeasible_column_and_witness(j, false, dep);
+                }  
+                else if (v < m_mpq_lar_core_solver.m_r_lower_bounds[j]) {
+                    set_infeasible_column_and_witness(j, true, dep);
+                }
+                else {
+                    set_upper_bound_witness(j, dep);
+                    set_lower_bound_witness(j, dep);
+                    m_mpq_lar_core_solver.m_r_upper_bounds[j] = m_mpq_lar_core_solver.m_r_lower_bounds[j] = v;
+                    insert_to_columns_with_changed_bounds(j);
                 }
-                set_upper_bound_witness(j, dep);
-                set_lower_bound_witness(j, dep);
-                m_mpq_lar_core_solver.m_r_upper_bounds[j] = m_mpq_lar_core_solver.m_r_lower_bounds[j] = v;
                 break;
             }
 
@@ -1979,7 +1983,7 @@ namespace lp {
             m_mpq_lar_core_solver.m_column_types[j] = column_type::fixed;
         }
     }
-    // clang-format off
+    
     void lar_solver::update_bound_with_no_ub_lb(var_index j, lconstraint_kind kind, const mpq& right_side, u_dependency* dep) {
         lp_assert(column_has_lower_bound(j) && !column_has_upper_bound(j));
         lp_assert(m_mpq_lar_core_solver.m_column_types[j] == column_type::lower_bound);
@@ -1991,12 +1995,14 @@ namespace lp {
             case LE: {
                 auto up = numeric_pair<mpq>(right_side, y_of_bound);
                 if (up < m_mpq_lar_core_solver.m_r_lower_bounds[j]) {
-                    set_infeasible_column(j);
+                    set_infeasible_column_and_witness(j, true, dep);
+                }
+                else {
+                    m_mpq_lar_core_solver.m_r_upper_bounds[j] = up;
+                    set_upper_bound_witness(j, dep);
+                    m_mpq_lar_core_solver.m_column_types[j] = (up == m_mpq_lar_core_solver.m_r_lower_bounds[j] ? column_type::fixed : column_type::boxed);
+                    insert_to_columns_with_changed_bounds(j);
                 }
-                m_mpq_lar_core_solver.m_r_upper_bounds[j] = up;
-                set_upper_bound_witness(j, dep);
-                m_mpq_lar_core_solver.m_column_types[j] = (up == m_mpq_lar_core_solver.m_r_lower_bounds[j] ? column_type::fixed : column_type::boxed);
-                insert_to_columns_with_changed_bounds(j);
                 break;
             } 
             case GT:
@@ -2014,13 +2020,15 @@ namespace lp {
             case EQ: {
                 auto v = numeric_pair<mpq>(right_side, zero_of_type<mpq>());
                 if (v < m_mpq_lar_core_solver.m_r_lower_bounds[j]) {
-                    set_infeasible_column(j);
+                    set_infeasible_column_and_witness(j, true, dep);
+                } 
+                else {
+                    set_upper_bound_witness(j, dep);
+                    set_lower_bound_witness(j, dep);
+                    m_mpq_lar_core_solver.m_r_upper_bounds[j] = m_mpq_lar_core_solver.m_r_lower_bounds[j] = v;
+                    m_mpq_lar_core_solver.m_column_types[j] = column_type::fixed;
+                    insert_to_columns_with_changed_bounds(j);
                 }
-
-                set_upper_bound_witness(j, dep);
-                set_lower_bound_witness(j, dep);
-                m_mpq_lar_core_solver.m_r_upper_bounds[j] = m_mpq_lar_core_solver.m_r_lower_bounds[j] = v;
-                m_mpq_lar_core_solver.m_column_types[j] = column_type::fixed;
                 break;
             }
 
@@ -2051,26 +2059,29 @@ namespace lp {
         {
             auto low = numeric_pair<mpq>(right_side, y_of_bound);
             if (low > m_mpq_lar_core_solver.m_r_upper_bounds[j]) {
-                set_infeasible_column(j);
+                set_infeasible_column_and_witness(j, false, dep);
+            }
+            else {
+                m_mpq_lar_core_solver.m_r_lower_bounds[j] = low;
+                set_lower_bound_witness(j, dep);
+                m_mpq_lar_core_solver.m_column_types[j] = (low == m_mpq_lar_core_solver.m_r_upper_bounds[j] ? column_type::fixed : column_type::boxed);
+                insert_to_columns_with_changed_bounds(j);
             }
-            m_mpq_lar_core_solver.m_r_lower_bounds[j] = low;
-            set_lower_bound_witness(j, dep);
-            m_mpq_lar_core_solver.m_column_types[j] = (low == m_mpq_lar_core_solver.m_r_upper_bounds[j] ? column_type::fixed : column_type::boxed);
-            insert_to_columns_with_changed_bounds(j);
-            
         }
         break;
         case EQ:
         {
             auto v = numeric_pair<mpq>(right_side, zero_of_type<mpq>());
             if (v > m_mpq_lar_core_solver.m_r_upper_bounds[j]) {
-                set_infeasible_column(j);
+                set_infeasible_column_and_witness(j, false, dep);
+            }
+            else {
+                set_upper_bound_witness(j, dep);
+                set_lower_bound_witness(j, dep);
+                m_mpq_lar_core_solver.m_r_upper_bounds[j] = m_mpq_lar_core_solver.m_r_lower_bounds[j] = v;
+                m_mpq_lar_core_solver.m_column_types[j] = column_type::fixed;
+                insert_to_columns_with_changed_bounds(j);
             }
-
-            set_upper_bound_witness(j, dep);
-            set_lower_bound_witness(j, dep);
-            m_mpq_lar_core_solver.m_r_upper_bounds[j] = m_mpq_lar_core_solver.m_r_lower_bounds[j] = v;
-            m_mpq_lar_core_solver.m_column_types[j] = column_type::fixed;
             break;
         }
 
@@ -2345,7 +2356,21 @@ namespace lp {
             return false;
         return true;
     }
+    // If lower_bound is true than the new asserted upper bound is less than the existing lower bound.
+    // Otherwise the new asserted lower bound is is greater than the existing upper bound.
+    // dep is the reason for the new bound
 
+    void lar_solver::set_infeasible_column_and_witness(unsigned j, bool lower_bound, u_dependency* dep) {
+        bool was_feas = column_is_feasible(j);
+        bool in_heap = m_mpq_lar_core_solver.m_r_solver.inf_heap().contains(j);
+        SASSERT(m_crossed_bounds_deps == nullptr && m_crossed_bounds_deps == nullptr);
+        set_status(lp_status::INFEASIBLE);
+        m_crossed_bounds_column = j;
+        const auto& ul = this->m_columns_to_ul_pairs()[j];
+        u_dependency* bdep = lower_bound? ul.lower_bound_witness() : ul.upper_bound_witness();
+        SASSERT(bdep != nullptr);
+        m_crossed_bounds_deps = m_dependencies.mk_join(bdep, dep);
+    }
 } // namespace lp
 
 
diff --git a/src/math/lp/lar_solver.h b/src/math/lp/lar_solver.h
index fc696d4b2..a689d6665 100644
--- a/src/math/lp/lar_solver.h
+++ b/src/math/lp/lar_solver.h
@@ -78,7 +78,8 @@ class lar_solver : public column_namer {
     lp_status m_status = lp_status::UNKNOWN;
     stacked_value<simplex_strategy_enum> m_simplex_strategy;
     // such can be found at the initialization step: u < l
-    stacked_value<int> m_crossed_bounds_column;
+    lpvar m_crossed_bounds_column;
+    u_dependency* m_crossed_bounds_deps;   
     lar_core_solver m_mpq_lar_core_solver;
     int_solver* m_int_solver = nullptr;
     bool m_need_register_terms = false;
@@ -139,10 +140,14 @@ class lar_solver : public column_namer {
     bool compare_values(impq const& lhs, lconstraint_kind k, const mpq& rhs);
 
     inline void clear_columns_with_changed_bounds() { m_columns_with_changed_bounds.reset(); }
+ public:   
     void insert_to_columns_with_changed_bounds(unsigned j);
+ private:   
     void update_column_type_and_bound_check_on_equal(unsigned j, const mpq& right_side, constraint_index ci, unsigned&);
     void update_column_type_and_bound(unsigned j, const mpq& right_side, constraint_index ci);
+ public:   
     void update_column_type_and_bound(unsigned j, lconstraint_kind kind, const mpq& right_side, u_dependency* dep);
+ private:   
     void update_column_type_and_bound_with_ub(var_index j, lconstraint_kind kind, const mpq& right_side, u_dependency* dep);
     void update_column_type_and_bound_with_no_ub(var_index j, lconstraint_kind kind, const mpq& right_side, u_dependency* dep);
     void update_bound_with_ub_lb(var_index j, lconstraint_kind kind, const mpq& right_side, u_dependency* dep);
@@ -152,10 +157,7 @@ class lar_solver : public column_namer {
     void register_in_fixed_var_table(unsigned, unsigned&);
     void remove_non_fixed_from_fixed_var_table();
     constraint_index add_var_bound_on_constraint_for_term(var_index j, lconstraint_kind kind, const mpq& right_side);
-    inline void set_infeasible_column(unsigned j) {
-        set_status(lp_status::INFEASIBLE);
-        m_crossed_bounds_column = j;
-    }
+    void set_infeasible_column_and_witness(unsigned j, bool lower_bound, u_dependency* dep);
     constraint_index add_constraint_from_term_and_create_new_column_row(unsigned term_j, const lar_term* term,
                                                                         lconstraint_kind kind, const mpq& right_side);
     unsigned row_of_basic_column(unsigned) const;
diff --git a/src/math/lp/lp_core_solver_base.h b/src/math/lp/lp_core_solver_base.h
index e7570d5dd..d7d1666d0 100644
--- a/src/math/lp/lp_core_solver_base.h
+++ b/src/math/lp/lp_core_solver_base.h
@@ -540,9 +540,9 @@ public:
     }
 
     void add_delta_to_x_and_track_feasibility(unsigned j, const X & del) {
-        TRACE("lar_solver_feas_bug", tout << "del = " << del << ", was x[" << j << "] = " << m_x[j] << "\n";);
+        TRACE("lar_solver_feas", tout << "del = " << del << ", was x[" << j << "] = " << m_x[j] << "\n";);
         m_x[j] += del;
-        TRACE("lar_solver_feas_bug", tout << "became x[" << j << "] = " << m_x[j] << "\n";);
+        TRACE("lar_solver_feas", tout << "became x[" << j << "] = " << m_x[j] << "\n";);
         track_column_feasibility(j);
     }
 
diff --git a/src/math/lp/monomial_bounds.cpp b/src/math/lp/monomial_bounds.cpp
index e21891ee4..9dd4ffa90 100644
--- a/src/math/lp/monomial_bounds.cpp
+++ b/src/math/lp/monomial_bounds.cpp
@@ -258,51 +258,113 @@ namespace nla {
         }
     }
 
-    void monomial_bounds::unit_propagate() {        
-        for (auto const& m : c().m_emons) 
-            unit_propagate(m);
+    bool monomial_bounds::unit_propagate() {  
+        unsigned sz = 0;
+        vector<lpvar> monics_vars;
+        for (auto const& m : c().m_emons) {
+            monics_vars.push_back(m.var());
+            sz++;
+        }
+        unsigned l = this->random();
+        for (unsigned i = 0; i < sz; ++i) {
+            lpvar v = monics_vars[(i + l) % sz];
+            if (!unit_propagate(c().m_emons[v])) {
+                return false;
+            }
+        }
+
+        return true;    
     }
 
-    void monomial_bounds::unit_propagate(monic const& m) {
+// returns false if and only if there is a conflict
+    bool monomial_bounds::unit_propagate(monic const& m) {
         m_propagated.reserve(m.var() + 1, false);
         if (m_propagated[m.var()])
-            return;
+            return true;
 
         if (!is_linear(m))
-            return;
+            return true;
         
         c().trail().push(set_bitvector_trail(m_propagated, m.var()));
-        
-        rational k = fixed_var_product(m);
-        
-        new_lemma lemma(c(), "fixed-values");
-        if (k == 0) {
-            for (auto v : m) {
-                if (c().var_is_fixed(v) && c().val(v).is_zero()) {
-                    lemma.explain_fixed(v);
+        lpvar zero_fixed = null_lpvar, non_fixed = null_lpvar;
+        // find a zero fixed variable and a non-fixed variable
+        for (lpvar v : m) {
+            if (c().var_is_fixed(v)) {
+                if (c().val(v).is_zero()) {
+                    zero_fixed = v;
                     break;
                 }
             }
-            lemma += ineq(m.var(), lp::lconstraint_kind::EQ, 0);
-        }
-        else {
-            for (auto v : m) 
-                if (c().var_is_fixed(v)) 
-                    lemma.explain_fixed(v);
-            
-            lpvar w = non_fixed_var(m);
-            if (w != null_lpvar) {
-                lp::lar_term term;
-                term.add_var(m.var());
-                term.add_monomial(-k, w);
-                lemma += ineq(term, lp::lconstraint_kind::EQ, 0);
-            } else {
-                lemma += ineq(m.var(), lp::lconstraint_kind::EQ, k);
+            else {
+                non_fixed = v;
             }
         }
-        
+
+        if (zero_fixed != null_lpvar) {
+            // the m.var() has to have a zero value
+            u_dependency* d = this->dep.mk_join(c().lra.get_column_lower_bound_witness(zero_fixed),
+                                                c().lra.get_column_upper_bound_witness(zero_fixed));
+
+            c().lra.update_column_type_and_bound(m.var(), lp::lconstraint_kind::EQ, mpq(0), d);
+        } else if (non_fixed != null_lpvar) {
+            u_dependency* d = nullptr;
+            rational k(1);
+            for (auto v : m)
+                if (v != non_fixed) {
+                    d = this->dep.mk_join(d, c().lra.get_column_upper_bound_witness(v));
+                    d = this->dep.mk_join(d, c().lra.get_column_lower_bound_witness(v));
+                    k *= c().val(v);
+                }
+            SASSERT(k.is_pos() || k.is_neg());
+            // we have m = k* non_fixed: m.var() getting the bounds witnesses of non_fixed
+            if (k.is_pos()) {
+                d = c().lra.get_column_upper_bound_witness(non_fixed);
+                if (d) {
+                    const auto& b = c().lra.get_column_value(non_fixed);
+                    bool strict = b.y.is_neg();
+                    c().lra.update_column_type_and_bound(m.var(), strict ? lp::lconstraint_kind::LT : lp::lconstraint_kind::LE, k * b.x, d);
+                }
+                d = c().lra.get_column_lower_bound_witness(non_fixed);
+                if (d) {
+                    const auto& b = c().lra.get_column_value(non_fixed);
+                    bool strict = b.y.is_pos();
+                    c().lra.update_column_type_and_bound(m.var(), strict ? lp::lconstraint_kind::GT : lp::lconstraint_kind::GE, k * b.x, d);
+                }
+
+            } else {
+                d = c().lra.get_column_upper_bound_witness(non_fixed);
+                if (d) {
+                    const auto& b = c().lra.get_column_value(non_fixed);
+                    bool strict = b.y.is_neg();
+                    c().lra.update_column_type_and_bound(m.var(), strict ? lp::lconstraint_kind::GT : lp::lconstraint_kind::GE, k * b.x, d);
+                }
+                d = c().lra.get_column_lower_bound_witness(non_fixed);
+                if (d) {
+                    const auto& b = c().lra.get_column_value(non_fixed);
+                    bool strict = b.y.is_pos();
+                    c().lra.update_column_type_and_bound(m.var(), strict ? lp::lconstraint_kind::LT : lp::lconstraint_kind::LE, k * b.x, d);                    
+                }
+            }
+        } else {
+            SASSERT(non_fixed == null_lpvar && zero_fixed == null_lpvar);
+            rational k(1);
+            u_dependency* d = nullptr;
+            for (auto v : m) {
+                SASSERT(c().var_is_fixed(v));
+                d = this->dep.mk_join(d, c().lra.get_column_upper_bound_witness(v));
+                d = this->dep.mk_join(d, c().lra.get_column_lower_bound_witness(v));
+                k *= c().val(v);
+            }
+            SASSERT(k.is_pos() || k.is_neg());
+            // we have m = k: m.var() getting the bounds witnesses of all fixed variables
+            c().lra.update_column_type_and_bound(m.var(), lp::lconstraint_kind::EQ, k, d);
+        }        
+        if (c().lra.get_status() == lp::lp_status::INFEASIBLE) {
+            TRACE("nla_solver", tout << "conflict in unit_propagate\n";);
+            return false;
+        }
+        return true;
     }
-    
     bool monomial_bounds::is_linear(monic const& m) {
         unsigned non_fixed = 0;
         for (lpvar v : m) {
@@ -324,12 +386,6 @@ namespace nla {
         return r;
     }
     
-    lpvar monomial_bounds::non_fixed_var(monic const& m) {
-        for (lpvar v : m) 
-            if (!c().var_is_fixed(v))
-                return v;
-        return null_lpvar;
-    }
-
+   
 }
 
diff --git a/src/math/lp/monomial_bounds.h b/src/math/lp/monomial_bounds.h
index c728d1a4c..41aa48f6c 100644
--- a/src/math/lp/monomial_bounds.h
+++ b/src/math/lp/monomial_bounds.h
@@ -32,14 +32,12 @@ namespace nla {
 
         // monomial propagation
         bool_vector m_propagated;
-        void unit_propagate(monic const& m);
+        bool unit_propagate(monic const& m);
         bool is_linear(monic const& m);
         rational fixed_var_product(monic const& m);
-        lpvar non_fixed_var(monic const& m);
-
     public:
         monomial_bounds(core* core);
         void propagate();
-        void unit_propagate();
+        bool unit_propagate();
     }; 
 }
diff --git a/src/math/lp/nla_core.cpp b/src/math/lp/nla_core.cpp
index 4d4fa6cbe..08a768ee5 100644
--- a/src/math/lp/nla_core.cpp
+++ b/src/math/lp/nla_core.cpp
@@ -1818,14 +1818,18 @@ bool core::improve_bounds() {
     }
     return bounds_improved;
 }
-    
-void core::propagate(vector<lemma>& lemmas) {
+    // returns false if and only if makes lp_solver inconsistent
+bool core::propagate(vector<lemma>& lemmas) {
    // propagate linear monomials, those that have all, or all but one, variables fixed
     lemmas.reset();
     m_lemma_vec = &lemmas;
  
     m_monomial_bounds.unit_propagate();
-   
+    if (lra.get_status() == lp::lp_status::INFEASIBLE) {
+        TRACE("nla_solver", tout << "propagation found infeasibility\n";);
+        return false;
+    }
+    return true;
 }
 
 
diff --git a/src/math/lp/nla_core.h b/src/math/lp/nla_core.h
index 9c96f2fbf..340b94430 100644
--- a/src/math/lp/nla_core.h
+++ b/src/math/lp/nla_core.h
@@ -392,7 +392,7 @@ public:
 
     bool  no_lemmas_hold() const;
 
-    void propagate(vector<lemma>& lemmas);
+    bool propagate(vector<lemma>& lemmas);
     
     lbool  test_check(vector<lemma>& l);
     lpvar map_to_root(lpvar) const;
diff --git a/src/smt/theory_arith_aux.h b/src/smt/theory_arith_aux.h
index 470ea5f7b..ae224e3ec 100644
--- a/src/smt/theory_arith_aux.h
+++ b/src/smt/theory_arith_aux.h
@@ -1532,11 +1532,12 @@ namespace smt {
         bool max, 
         bool maintain_integrality, 
         bool& has_shared) {
+        return UNBOUNDED;    
+
         m_stats.m_max_min++;
         unsigned best_efforts = 0;
         bool inc = false;
-
-
+        
         SASSERT(!maintain_integrality || valid_assignment());
         SASSERT(satisfy_bounds());
 
diff --git a/src/smt/theory_arith_nl.h b/src/smt/theory_arith_nl.h
index f44516cad..77e2b25f3 100644
--- a/src/smt/theory_arith_nl.h
+++ b/src/smt/theory_arith_nl.h
@@ -511,6 +511,7 @@ bool theory_arith<Ext>::propagate_nl_downward(expr * n, var_power_pair const& p)
 */
 template<typename Ext>
 bool theory_arith<Ext>::propagate_nl_bounds(expr * m) {
+    return false;
     TRACE("non_linear", tout << "propagate several bounds using:\n"; display_monomial(tout, m); tout << "\n";);
     bool result = propagate_nl_upward(m);
     buffer<var_power_pair> vp;
@@ -530,6 +531,7 @@ bool theory_arith<Ext>::propagate_nl_bounds(expr * m) {
 */
 template<typename Ext>
 bool theory_arith<Ext>::propagate_nl_bounds() {
+    return false;
     m_dep_manager.reset();
     bool propagated = false;
     for (unsigned i = 0; i < m_nl_monomials.size(); i++) {
@@ -1632,6 +1634,7 @@ bool theory_arith<Ext>::is_cross_nested_consistent(row const & r) {
 */
 template<typename Ext>
 bool theory_arith<Ext>::is_cross_nested_consistent(svector<theory_var> const & nl_cluster) {
+    return true;
     for (theory_var v : nl_cluster) {
         if (!is_base(v))
             continue;
diff --git a/src/smt/theory_lra.cpp b/src/smt/theory_lra.cpp
index 31882ea11..29a46db19 100644
--- a/src/smt/theory_lra.cpp
+++ b/src/smt/theory_lra.cpp
@@ -2163,8 +2163,14 @@ public:
         if (!m_nla)
             return;
         m_nla->propagate(m_nla_lemma_vector);
-        for (nla::lemma const& l : m_nla_lemma_vector)
-            false_case_of_check_nla(l);
+        if (lp().get_status() == lp::lp_status::INFEASIBLE) {
+            TRACE("arith", tout << "propagation conflict\n";);
+            get_infeasibility_explanation_and_set_conflict();
+        } 
+        else {
+            for (nla::lemma const& l : m_nla_lemma_vector)
+                false_case_of_check_nla(l);
+        }
     }
 
     bool should_propagate() const {