diff --git a/src/ast/sls/bv_sls_eval.h b/src/ast/sls/bv_sls_eval.h
index 89cd3f4cf03..4384660e79a 100644
--- a/src/ast/sls/bv_sls_eval.h
+++ b/src/ast/sls/bv_sls_eval.h
@@ -25,6 +25,12 @@ namespace bv {
 
     class sls_fixed;
 
+    class sls_eval_plugin {
+    public:
+        virtual ~sls_eval_plugin() {}
+        
+    };
+
     class sls_eval {
         struct config {
             unsigned m_prob_randomize_extract = 50;
@@ -40,6 +46,8 @@ namespace bv {
         random_gen          m_rand;
         config              m_config;
 
+        scoped_ptr_vector<sls_eval_plugin> m_plugins;
+
 
 
         scoped_ptr_vector<sls_valuation> m_values; // expr-id -> bv valuation
diff --git a/src/math/lp/nra_solver.cpp b/src/math/lp/nra_solver.cpp
index 9c9db4e4114..4c1b2b3eef8 100644
--- a/src/math/lp/nra_solver.cpp
+++ b/src/math/lp/nra_solver.cpp
@@ -3,6 +3,10 @@
   Author: Nikolaj Bjorner, Lev Nachmanson
 */
 
+#ifndef SINGLE_THREAD
+#include <thread>
+#endif
+#include <fstream>
 #include "math/lp/lar_solver.h"
 #include "math/lp/nra_solver.h"
 #include "nlsat/nlsat_solver.h"
@@ -11,6 +15,7 @@
 #include "util/map.h"
 #include "util/uint_set.h"
 #include "math/lp/nla_core.h"
+#include "smt/params/smt_params_helper.hpp"
 
 
 namespace nra {
@@ -157,6 +162,23 @@ struct solver::imp {
 
         TRACE("nra", m_nlsat->display(tout));
 
+        smt_params_helper p(m_params);
+        if (p.arith_nl_log()) {
+            static unsigned id = 0;
+            std::stringstream strm;
+
+#ifndef SINGLE_THREAD            
+            std::thread::id this_id = std::this_thread::get_id();
+            strm << "nla_" << this_id << "." << (++id) << ".smt2";
+#else
+            strm << "nla_" << (++id) << ".smt2";
+#endif
+            std::ofstream out(strm.str());
+            m_nlsat->display_smt2(out);
+            out << "(check-sat)\n";
+            out.close();
+        }
+
         lbool r = l_undef;
         try {
             r = m_nlsat->check();
diff --git a/src/nlsat/nlsat_solver.cpp b/src/nlsat/nlsat_solver.cpp
index d99603dcddc..7a63f4e636b 100644
--- a/src/nlsat/nlsat_solver.cpp
+++ b/src/nlsat/nlsat_solver.cpp
@@ -3863,6 +3863,10 @@ namespace nlsat {
         return out;
     }
 
+    std::ostream& solver::display_smt2(std::ostream & out) const {
+        return m_imp->display_smt2(out);
+    }
+
     std::ostream& solver::display_smt2(std::ostream & out, literal_vector const& ls) const {
         return display_smt2(out, ls.size(), ls.data());
     }
diff --git a/src/nlsat/nlsat_solver.h b/src/nlsat/nlsat_solver.h
index c65a2b4ff79..15764150d7d 100644
--- a/src/nlsat/nlsat_solver.h
+++ b/src/nlsat/nlsat_solver.h
@@ -254,6 +254,8 @@ namespace nlsat {
 
         std::ostream& display_smt2(std::ostream & out, literal_vector const& ls) const;
 
+                std::ostream& display_smt2(std::ostream & out) const;
+
 
         /**
            \brief Display variable
diff --git a/src/smt/params/smt_params_helper.pyg b/src/smt/params/smt_params_helper.pyg
index 4e498b2c461..1ef795e4b7d 100644
--- a/src/smt/params/smt_params_helper.pyg
+++ b/src/smt/params/smt_params_helper.pyg
@@ -83,6 +83,7 @@ def_module_params(module_name='smt',
 			  ('arith.nl.propagate_linear_monomials', BOOL, True, 'propagate linear monomials'),
 			  ('arith.nl.optimize_bounds', BOOL, True, 'enable bounds optimization'),
 			  ('arith.nl.cross_nested', BOOL, True, 'enable cross-nested consistency checking'),
+			  ('arith.nl.log', BOOL, False, 'Log lemmas sent to nra solver'),
                           ('arith.propagate_eqs', BOOL, True, 'propagate (cheap) equalities'),
                           ('arith.propagation_mode', UINT, 1, '0 - no propagation, 1 - propagate existing literals, 2 - refine finite bounds'),
                           ('arith.branch_cut_ratio', UINT, 2, 'branch/cut ratio for linear integer arithmetic'),