diff --git a/src/muz_qe/datalog_parser.cpp b/src/muz_qe/datalog_parser.cpp
index cfe283410..545f3e14a 100644
--- a/src/muz_qe/datalog_parser.cpp
+++ b/src/muz_qe/datalog_parser.cpp
@@ -441,6 +441,7 @@ protected:
     unsigned          m_sym_idx;
     std::string       m_path;
     str2sort          m_sort_dict;
+
     
     // true if an error occured during the current call to the parse_stream
     // function
@@ -812,7 +813,8 @@ protected:
             }
             f = m_manager.mk_func_decl(s, domain.size(), domain.c_ptr(), m_manager.mk_bool_sort());
 
-            m_context.register_predicate(f);
+            m_context.register_predicate(f, true);
+        
             while (tok == TK_ID) {
                 char const* pred_pragma = m_lexer->get_token_data();
                 if(strcmp(pred_pragma, "printtuples")==0 || strcmp(pred_pragma, "outputtuples")==0) {
diff --git a/src/muz_qe/dl_mk_quantifier_abstraction.cpp b/src/muz_qe/dl_mk_quantifier_abstraction.cpp
new file mode 100644
index 000000000..d4abb1ffc
--- /dev/null
+++ b/src/muz_qe/dl_mk_quantifier_abstraction.cpp
@@ -0,0 +1,367 @@
+/*++
+Copyright (c) 2013 Microsoft Corporation
+
+Module Name:
+
+    dl_mk_quantifier_abstraction.cpp
+
+Abstract:
+
+    Create quantified Horn clauses from benchmarks with arrays.
+
+Author:
+
+    Ken McMillan 
+    Andrey Rybalchenko
+    Nikolaj Bjorner (nbjorner) 2013-04-02
+
+Revision History:
+
+--*/
+
+#include "dl_mk_quantifier_abstraction.h"
+#include "dl_context.h"
+#include "expr_safe_replace.h"
+#include "expr_abstract.h"
+
+namespace datalog {
+
+
+    // model converter: 
+    // Given model for P^(x, y, i, a[i])
+    // create model: P(x,y,a) == forall i . P^(x,y,i,a[i])
+    // requires substitution and list of bound variables.
+
+    class mk_quantifier_abstraction::qa_model_converter : public model_converter {
+        ast_manager&            m;
+        func_decl_ref_vector    m_old_funcs;
+        func_decl_ref_vector    m_new_funcs;
+        vector<expr_ref_vector> m_subst;
+        vector<sort_ref_vector> m_sorts;
+        vector<svector<bool> >  m_bound;
+
+    public:
+
+        qa_model_converter(ast_manager& m):
+            m(m), m_old_funcs(m), m_new_funcs(m) {}
+
+        virtual ~qa_model_converter() {}
+
+        virtual model_converter * translate(ast_translation & translator) { 
+            return alloc(qa_model_converter, m);
+        }
+
+        void insert(func_decl* old_p, func_decl* new_p, expr_ref_vector& sub, sort_ref_vector& sorts, svector<bool> const& bound) {
+            m_old_funcs.push_back(old_p);
+            m_new_funcs.push_back(new_p);
+            m_subst.push_back(sub);
+            m_bound.push_back(bound);
+            m_sorts.push_back(sorts);
+        }
+
+        virtual void operator()(model_ref & old_model) {
+            model_ref new_model = alloc(model, m);
+            for (unsigned i = 0; i < m_new_funcs.size(); ++i) {
+                func_decl* p = m_new_funcs[i].get();
+                func_decl* q = m_old_funcs[i].get();
+                expr_ref_vector const& sub = m_subst[i];
+                sort_ref_vector const& sorts = m_sorts[i];
+                svector<bool> const& is_bound  = m_bound[i];
+                func_interp* f = old_model->get_func_interp(p);
+                expr_ref body(m);                
+                unsigned arity_p = p->get_arity();
+                unsigned arity_q = q->get_arity();
+                SASSERT(0 < arity_p);
+                func_interp* g = alloc(func_interp, m, arity_q);
+
+                if (f) {
+                    body = f->get_interp();
+                    SASSERT(!f->is_partial());
+                    SASSERT(body);                    
+                }
+                else {
+                    body = m.mk_false();  
+                }
+                // Create quantifier wrapper around body.
+
+                TRACE("dl", tout << mk_pp(body, m) << "\n";);
+                // 1. replace variables by the compound terms from 
+                //    the original predicate.
+                expr_safe_replace rep(m);
+                for (unsigned i = 0; i < sub.size(); ++i) {
+                    rep.insert(m.mk_var(i, m.get_sort(sub[i])), sub[i]);
+                }
+                rep(body);
+                rep.reset();
+
+                TRACE("dl", tout << mk_pp(body, m) << "\n";);
+                // 2. replace bound variables by constants.
+                expr_ref_vector consts(m), bound(m), free(m);
+                svector<symbol> names;
+                ptr_vector<sort> bound_sorts;
+                for (unsigned i = 0; i < sorts.size(); ++i) {
+                    sort* s = sorts[i];
+                    consts.push_back(m.mk_fresh_const("C", s));
+                    rep.insert(m.mk_var(i, s), consts.back());
+                    if (is_bound[i]) {
+                        bound.push_back(consts.back());
+                        names.push_back(symbol(i));
+                        bound_sorts.push_back(s);
+                    }
+                    else {
+                        free.push_back(consts.back());
+                    }
+                }
+                rep(body);                
+                rep.reset();
+
+                TRACE("dl", tout << mk_pp(body, m) << "\n";);
+                // 3. abstract and quantify those variables that should be bound.
+                expr_abstract(m, 0, bound.size(), bound.c_ptr(), body, body);
+                body = m.mk_forall(names.size(), bound_sorts.c_ptr(), names.c_ptr(), body);
+
+                TRACE("dl", tout << mk_pp(body, m) << "\n";);
+                // 4. replace remaining constants by variables.                                
+                for (unsigned i = 0; i < free.size(); ++i) {
+                    rep.insert(free[i].get(), m.mk_var(i, m.get_sort(free[i].get())));
+                }
+                rep(body);                
+                g->set_else(body);
+                TRACE("dl", tout << mk_pp(body, m) << "\n";);
+
+                new_model->register_decl(q, g);
+            }  
+            old_model = new_model;
+        }                        
+    };
+
+    mk_quantifier_abstraction::mk_quantifier_abstraction(
+        context & ctx, unsigned priority):
+        plugin(priority),
+        m(ctx.get_manager()),
+        m_ctx(ctx),
+        a(m),
+        m_refs(m) {        
+    }
+
+    mk_quantifier_abstraction::~mk_quantifier_abstraction() {        
+    }
+
+    func_decl* mk_quantifier_abstraction::declare_pred(func_decl* old_p) {
+
+        if (m_ctx.is_output_predicate(old_p)) {
+            return 0;
+        }
+
+        unsigned sz = old_p->get_arity();
+        unsigned num_arrays = 0;
+        for (unsigned i = 0; i < sz; ++i) {
+            if (a.is_array(old_p->get_domain(i))) {
+                num_arrays++;
+            }
+        }
+        if (num_arrays == 0) {
+            return 0;
+        }
+
+        func_decl* new_p = 0;
+        if (!m_old2new.find(old_p, new_p)) {
+            expr_ref_vector sub(m), vars(m);
+            svector<bool> bound;            
+            sort_ref_vector domain(m), sorts(m);
+            expr_ref arg(m);
+            for (unsigned i = 0; i < sz; ++i) {
+                sort* s0 = old_p->get_domain(i);
+                unsigned lookahead = 0;
+                sort* s = s0;
+                while (a.is_array(s)) {
+                    lookahead += get_array_arity(s);
+                    s = get_array_range(s);
+                }
+                arg = m.mk_var(bound.size() + lookahead, s0);
+                s = s0;
+                while (a.is_array(s)) {
+                    unsigned arity = get_array_arity(s);
+                    expr_ref_vector args(m);
+                    for (unsigned j = 0; j < arity; ++j) {
+                        sort* s1 = get_array_domain(s, j);
+                        domain.push_back(s1);
+                        args.push_back(m.mk_var(bound.size(), s1));
+                        bound.push_back(true);
+                        sorts.push_back(s1);
+                    }
+                    arg = mk_select(arg, args.size(), args.c_ptr());
+                    s = get_array_range(s);
+                }
+                domain.push_back(s);
+                bound.push_back(false);
+                sub.push_back(arg);
+                sorts.push_back(s0);
+            }          
+            SASSERT(old_p->get_range() == m.mk_bool_sort());
+            new_p = m.mk_func_decl(old_p->get_name(), domain.size(), domain.c_ptr(), old_p->get_range());
+            m_refs.push_back(new_p);
+            m_ctx.register_predicate(new_p, false);
+            if (m_mc) {
+                m_mc->insert(old_p, new_p, sub, sorts, bound);
+            }
+            m_old2new.insert(old_p, new_p);
+        }
+        return new_p;
+    }
+
+    app_ref mk_quantifier_abstraction::mk_head(app* p, unsigned idx) {
+        func_decl* new_p = declare_pred(p->get_decl());
+        if (!new_p) {
+            return app_ref(p, m);
+        }
+        expr_ref_vector args(m);
+        expr_ref arg(m);
+        unsigned sz = p->get_num_args();
+        for (unsigned i = 0; i < sz; ++i) {
+            arg = p->get_arg(i);
+            sort* s = m.get_sort(arg);
+            while (a.is_array(s)) {
+                unsigned arity = get_array_arity(s);
+                for (unsigned j = 0; j < arity; ++j) {
+                    args.push_back(m.mk_var(idx++, get_array_domain(s, j)));
+                }
+                arg = mk_select(arg, arity, args.c_ptr()+args.size()-arity);
+                s = get_array_range(s);
+            }
+            args.push_back(arg);
+        }
+        TRACE("dl", 
+              tout << mk_pp(new_p, m) << "\n";
+              for (unsigned i = 0; i < args.size(); ++i) {
+                  tout << mk_pp(args[i].get(), m) << "\n";
+              });
+        return app_ref(m.mk_app(new_p, args.size(), args.c_ptr()), m);        
+    }
+
+    app_ref mk_quantifier_abstraction::mk_tail(app* p) {
+        func_decl* old_p = p->get_decl();
+        func_decl* new_p = declare_pred(old_p);
+        if (!new_p) {
+            return app_ref(p, m);
+        }
+        SASSERT(new_p->get_arity() > old_p->get_arity());
+        unsigned num_extra_args = new_p->get_arity() - old_p->get_arity();
+        var_shifter shift(m);
+        expr_ref p_shifted(m);
+        shift(p, num_extra_args, p_shifted);
+        app* ps = to_app(p_shifted);
+        expr_ref_vector args(m);
+        app_ref_vector  pats(m);
+        sort_ref_vector vars(m);
+        svector<symbol> names;
+        expr_ref arg(m);
+        unsigned idx = 0;
+        unsigned sz = p->get_num_args();
+        for (unsigned i = 0; i < sz; ++i) {
+            arg = ps->get_arg(i);
+            sort* s = m.get_sort(arg);
+            bool is_pattern = false;            
+            while (a.is_array(s)) {
+                is_pattern = true;
+                unsigned arity = get_array_arity(s);
+                for (unsigned j = 0; j < arity; ++j) {
+                    vars.push_back(get_array_domain(s, j));
+                    names.push_back(symbol(idx));
+                    args.push_back(m.mk_var(idx++, vars.back()));
+                }
+                arg = mk_select(arg, arity, args.c_ptr()+args.size()-arity);
+                s = get_array_range(s);
+            }
+            if (is_pattern) {
+                pats.push_back(to_app(arg));
+            }
+            args.push_back(arg);
+        }
+        expr* pat = 0;
+        expr_ref pattern(m);
+        pattern = m.mk_pattern(pats.size(), pats.c_ptr());
+        pat = pattern.get();
+        app_ref result(m);
+        symbol qid, skid;
+        result = m.mk_app(new_p, args.size(), args.c_ptr());
+        result = m.mk_eq(m.mk_forall(vars.size(), vars.c_ptr(), names.c_ptr(), result, 1, qid, skid, 1, &pat), m.mk_true());
+        return result;
+    }
+
+    expr * mk_quantifier_abstraction::mk_select(expr* arg, unsigned num_args, expr* const* args) {
+        ptr_vector<expr> args2;
+        args2.push_back(arg);
+        args2.append(num_args, args);
+        return a.mk_select(args2.size(), args2.c_ptr());                
+    }
+        
+    rule_set * mk_quantifier_abstraction::operator()(rule_set const & source) {
+        TRACE("dl", tout << "quantify " << source.get_num_rules() << " " << m_ctx.get_params().quantify_arrays() << "\n";);
+        if (!m_ctx.get_params().quantify_arrays()) {
+            return 0;
+        }
+        unsigned sz = source.get_num_rules();
+        for (unsigned i = 0; i < sz; ++i) {
+            rule& r = *source.get_rule(i);
+            if (r.has_negation()) {
+                return 0;
+            }
+        }
+
+        m_refs.reset();
+        m_old2new.reset();
+        m_new2old.reset();
+        rule_manager& rm = source.get_rule_manager();
+        rule_ref new_rule(rm);
+        expr_ref_vector tail(m);
+        app_ref head(m);
+        expr_ref fml(m);
+        rule_counter& vc = rm.get_counter();
+
+        if (m_ctx.get_model_converter()) {
+            m_mc = alloc(qa_model_converter, m);
+        }
+        rule_set * result = alloc(rule_set, m_ctx);
+
+        for (unsigned i = 0; i < sz; ++i) {      
+            tail.reset();
+            rule & r = *source.get_rule(i);
+            TRACE("dl", r.display(m_ctx, tout); );      
+            unsigned cnt = vc.get_max_rule_var(r)+1;
+            unsigned utsz = r.get_uninterpreted_tail_size();
+            unsigned tsz = r.get_tail_size();
+            for (unsigned j = 0; j < utsz; ++j) {
+                tail.push_back(mk_tail(r.get_tail(j)));
+            }
+            for (unsigned j = utsz; j < tsz; ++j) {
+                tail.push_back(r.get_tail(j));
+            }
+            head = mk_head(r.get_head(), cnt);
+            fml = m.mk_implies(m.mk_and(tail.size(), tail.c_ptr()), head);
+            rule_ref_vector added_rules(rm);
+            proof_ref pr(m);
+            rm.mk_rule(fml, pr, added_rules);
+            result->add_rules(added_rules.size(), added_rules.c_ptr());
+            TRACE("dl", added_rules.back()->display(m_ctx, tout););
+        }        
+        
+        // proof converter: proofs are not necessarily preserved using this transformation.
+
+        if (m_old2new.empty()) {
+            dealloc(result);
+            dealloc(m_mc);
+            result = 0;
+        }
+        else {
+            m_ctx.add_model_converter(m_mc);
+        }
+        m_mc = 0;
+
+        return result;
+    }
+
+
+};
+
+
diff --git a/src/muz_qe/dl_mk_quantifier_abstraction.h b/src/muz_qe/dl_mk_quantifier_abstraction.h
new file mode 100644
index 000000000..c7e6c6bb4
--- /dev/null
+++ b/src/muz_qe/dl_mk_quantifier_abstraction.h
@@ -0,0 +1,64 @@
+/*++
+Copyright (c) 2013 Microsoft Corporation
+
+Module Name:
+
+    dl_mk_quantifier_abstraction.h
+
+Abstract:
+
+    Convert clauses with array arguments to predicates 
+    into Quantified Horn clauses.
+
+Author:
+
+    Ken McMillan 
+    Andrey Rybalchenko
+    Nikolaj Bjorner (nbjorner) 2013-04-02
+
+Revision History:
+
+    Based on approach suggested in SAS 2013 paper 
+    "On Solving Universally Quantified Horn Clauses"    
+
+--*/
+#ifndef _DL_MK_QUANTIFIER_ABSTRACTION_H_
+#define _DL_MK_QUANTIFIER_ABSTRACTION_H_
+
+
+#include"dl_rule_transformer.h"
+#include"array_decl_plugin.h"
+
+namespace datalog {
+
+    class context;
+
+    class mk_quantifier_abstraction : public rule_transformer::plugin {
+        class qa_model_converter;
+        ast_manager& m;
+        context&     m_ctx;
+        array_util   a;
+        func_decl_ref_vector           m_refs;
+        obj_map<func_decl, func_decl*> m_new2old;
+        obj_map<func_decl, func_decl*> m_old2new;
+        qa_model_converter*            m_mc;
+
+        func_decl* declare_pred(func_decl* old_p);
+        app_ref mk_head(app* p, unsigned idx);
+        app_ref mk_tail(app* p);
+        expr*   mk_select(expr* a, unsigned num_args, expr* const* args);
+
+    public:
+        mk_quantifier_abstraction(context & ctx, unsigned priority);
+
+        virtual ~mk_quantifier_abstraction();
+        
+        rule_set * operator()(rule_set const & source);
+    };
+
+
+
+};
+
+#endif /* _DL_MK_QUANTIFIER_ABSTRACTION_H_ */
+
diff --git a/src/muz_qe/dl_mk_quantifier_instantiation.cpp b/src/muz_qe/dl_mk_quantifier_instantiation.cpp
new file mode 100644
index 000000000..993e5ada5
--- /dev/null
+++ b/src/muz_qe/dl_mk_quantifier_instantiation.cpp
@@ -0,0 +1,300 @@
+/*++
+Copyright (c) 2013 Microsoft Corporation
+
+Module Name:
+
+    dl_mk_quantifier_instantiation.cpp
+
+Abstract:
+
+    Convert Quantified Horn clauses into non-quantified clauses using
+    instantiation.
+
+Author:
+
+    Ken McMillan 
+    Andrey Rybalchenko
+    Nikolaj Bjorner (nbjorner) 2013-04-02
+
+Revision History:
+
+    Based on approach suggested in the SAS 2013 paper 
+    "On Solving Universally Quantified Horn Clauses"    
+
+--*/
+
+#include "dl_mk_quantifier_instantiation.h"
+#include "dl_context.h"
+#include "pattern_inference.h"
+
+namespace datalog {
+
+    mk_quantifier_instantiation::mk_quantifier_instantiation(
+        context & ctx, unsigned priority):
+        plugin(priority),
+        m(ctx.get_manager()),
+        m_ctx(ctx),
+        m_var2cnst(m),
+        m_cnst2var(m) {        
+    }
+
+    mk_quantifier_instantiation::~mk_quantifier_instantiation() {        
+    }
+
+    void mk_quantifier_instantiation::extract_quantifiers(rule& r, expr_ref_vector& conjs, quantifier_ref_vector& qs) {
+        conjs.reset();
+        qs.reset();
+        unsigned tsz = r.get_tail_size();
+        for (unsigned j = 0; j < tsz; ++j) {
+            conjs.push_back(r.get_tail(j));            
+        }
+        datalog::flatten_and(conjs);
+        for (unsigned j = 0; j < conjs.size(); ++j) {
+            expr* e = conjs[j].get();
+            quantifier* q;
+            if (rule_manager::is_forall(m, e, q)) {
+                qs.push_back(q);
+                conjs[j] = conjs.back();
+                conjs.pop_back();
+                --j;
+            }
+        }
+    }
+
+    void mk_quantifier_instantiation::instantiate_quantifier(quantifier* q, expr_ref_vector & conjs) {
+        expr_ref qe(m);
+        qe = q;
+        m_var2cnst(qe);        
+        q = to_quantifier(qe);
+        if (q->get_num_patterns() == 0) {
+            proof_ref new_pr(m);
+            pattern_inference_params params;
+            pattern_inference infer(m, params);
+            infer(q, qe, new_pr);
+            q = to_quantifier(qe);
+        }
+        unsigned num_patterns = q->get_num_patterns();
+        for (unsigned i = 0; i < num_patterns; ++i) {
+            expr * pat = q->get_pattern(i);
+            SASSERT(m.is_pattern(pat));
+            instantiate_quantifier(q, to_app(pat), conjs);
+        }
+    }
+
+
+    void mk_quantifier_instantiation::instantiate_quantifier(quantifier* q, app* pat, expr_ref_vector & conjs) {
+        unsigned sz = pat->get_num_args();
+        m_binding.reset();
+        m_binding.resize(q->get_num_decls());
+        term_pairs todo;
+        match(0, pat, 0, todo, q, conjs);
+    }
+
+    void mk_quantifier_instantiation::match(unsigned i, app* pat, unsigned j, term_pairs& todo, quantifier* q, expr_ref_vector& conjs) {
+        TRACE("dl", tout << "match" << mk_pp(pat, m) << "\n";);
+        while (j < todo.size()) {
+            expr* p = todo[j].first;
+            expr* t = todo[j].second;
+            if (is_var(p)) {
+                unsigned idx = to_var(p)->get_idx();
+                if (!m_binding[idx]) {
+                    m_binding[idx] = t;
+                    match(i, pat, j + 1, todo, q, conjs);
+                    m_binding[idx] = 0;
+                    return;
+                }
+                ++j;
+                continue;
+            }
+            if (!is_app(p)) {
+                return;
+            }
+            app* a1 = to_app(p);
+            unsigned id = t->get_id();
+            unsigned next_id = id;
+            unsigned sz = todo.size();
+            do {
+                expr* t2 = m_terms[next_id];
+                if (is_app(t2)) {
+                    app* a2 = to_app(t2);
+                    if (a1->get_decl() == a2->get_decl() &&
+                        a1->get_num_args() == a2->get_num_args()) {
+                        for (unsigned k = 0; k < a1->get_num_args(); ++k) {
+                            todo.push_back(std::make_pair(a1->get_arg(k), a2->get_arg(k)));
+                        }
+                        match(i, pat, j + 1, todo, q, conjs);
+                        todo.resize(sz);
+                    }                    
+                }
+                next_id = m_uf.next(next_id);
+            }
+            while (next_id != id);
+            return;
+        }
+
+        if (i == pat->get_num_args()) {
+            yield_binding(q, conjs);
+            return;
+        }
+        expr* arg = pat->get_arg(i);
+        ptr_vector<expr>* terms = 0;
+    
+        if (m_funs.find(to_app(arg)->get_decl(), terms)) {
+            for (unsigned k = 0; k < terms->size(); ++k) {
+                todo.push_back(std::make_pair(arg, (*terms)[k]));
+                match(i + 1, pat, j, todo, q, conjs);
+                todo.pop_back();
+            }
+        }
+    }
+
+    void mk_quantifier_instantiation::yield_binding(quantifier* q, expr_ref_vector& conjs) {
+        DEBUG_CODE(
+            for (unsigned i = 0; i < m_binding.size(); ++i) {
+                SASSERT(m_binding[i]);
+            });
+        m_binding.reverse();
+        expr_ref res(m);
+        instantiate(m, q, m_binding.c_ptr(), res);
+        m_binding.reverse();
+        m_cnst2var(res);
+        conjs.push_back(res);
+        TRACE("dl", tout << mk_pp(q, m) << "\n==>\n" << mk_pp(res, m) << "\n";);
+    }
+
+    void mk_quantifier_instantiation::collect_egraph(expr* e) {
+        expr* e1, *e2;
+        m_todo.push_back(e);
+        expr_fast_mark1 visited;
+        while (!m_todo.empty()) {
+            e = m_todo.back();
+            m_todo.pop_back();
+            if (visited.is_marked(e)) {
+                continue;
+            }
+            unsigned n = e->get_id();
+            if (n >= m_terms.size()) {
+                m_terms.resize(n+1);
+            }
+            m_terms[n] = e;
+            visited.mark(e);
+            if (m.is_eq(e, e1, e2) || m.is_iff(e, e1, e2)) {
+                m_uf.merge(e1->get_id(), e2->get_id());
+            }
+            if (is_app(e)) {
+                app* ap = to_app(e);
+                ptr_vector<expr>* terms = 0;
+                if (!m_funs.find(ap->get_decl(), terms)) {
+                    terms = alloc(ptr_vector<expr>);
+                    m_funs.insert(ap->get_decl(), terms);
+                }
+                terms->push_back(e);
+                m_todo.append(ap->get_num_args(), ap->get_args());
+            }
+        }
+    }
+
+    void mk_quantifier_instantiation::instantiate_rule(rule& r, expr_ref_vector& conjs, quantifier_ref_vector& qs, rule_set& rules) {
+        rule_manager& rm = m_ctx.get_rule_manager();
+        expr_ref fml(m), cnst(m);
+        var_ref var(m);
+        ptr_vector<sort> sorts;
+        r.get_vars(sorts);
+        m_uf.reset();
+        m_terms.reset();
+        m_var2cnst.reset();
+        m_cnst2var.reset();
+        fml = m.mk_and(conjs.size(), conjs.c_ptr());
+
+        for (unsigned i = 0; i < sorts.size(); ++i) {
+            if (!sorts[i]) {
+                sorts[i] = m.mk_bool_sort();
+            }
+            var = m.mk_var(i, sorts[i]);
+            cnst = m.mk_fresh_const("C", sorts[i]);
+            m_var2cnst.insert(var, cnst);
+            m_cnst2var.insert(cnst, var);
+        }
+
+        fml = m.mk_and(conjs.size(), conjs.c_ptr());
+        m_var2cnst(fml);
+        collect_egraph(fml);
+
+        for (unsigned i = 0; i < qs.size(); ++i) {
+            instantiate_quantifier(qs[i].get(), conjs);
+        }
+        obj_map<func_decl, ptr_vector<expr>*>::iterator it = m_funs.begin(), end = m_funs.end();
+        for (; it != end; ++it) {
+            dealloc(it->m_value);
+        }
+        m_funs.reset();
+
+        fml = m.mk_and(conjs.size(), conjs.c_ptr());
+        fml = m.mk_implies(fml, r.get_head());
+        TRACE("dl", r.display(m_ctx, tout); tout << mk_pp(fml, m) << "\n";);
+        
+        rule_ref_vector added_rules(rm);
+        proof_ref pr(m); 
+        rm.mk_rule(fml, pr, added_rules);
+        if (r.get_proof()) {
+            // use def-axiom to encode that new rule is a weakening of the original.
+            proof* p1 = r.get_proof();
+            for (unsigned i = 0; i < added_rules.size(); ++i) {
+                rule* r2 = added_rules[i].get();
+                r2->to_formula(fml);
+                pr = m.mk_modus_ponens(m.mk_def_axiom(m.mk_implies(m.get_fact(p1), fml)), p1);
+                r2->set_proof(m, pr);
+            }
+        }
+        rules.add_rules(added_rules.size(), added_rules.c_ptr());
+    }
+        
+    rule_set * mk_quantifier_instantiation::operator()(rule_set const & source) {
+        TRACE("dl", tout << m_ctx.get_params().instantiate_quantifiers() << "\n";);
+        if (!m_ctx.get_params().instantiate_quantifiers()) {
+            return 0;
+        }
+        bool has_quantifiers = false;
+        unsigned sz = source.get_num_rules();
+        for (unsigned i = 0; !has_quantifiers && i < sz; ++i) {
+            rule& r = *source.get_rule(i);
+            has_quantifiers = has_quantifiers || r.has_quantifiers();   
+            if (r.has_negation()) {
+                return 0;
+            }
+        }
+        if (!has_quantifiers) {
+            return 0;
+        }
+
+        expr_ref_vector conjs(m);
+        quantifier_ref_vector qs(m);
+        rule_set * result = alloc(rule_set, m_ctx);
+
+        bool instantiated = false;
+
+        for (unsigned i = 0; i < sz; ++i) {       
+            rule * r = source.get_rule(i);
+            extract_quantifiers(*r, conjs, qs);
+            if (qs.empty()) {
+                result->add_rule(r);
+            }
+            else {
+                instantiate_rule(*r, conjs, qs, *result);
+                instantiated = true;
+            }
+        }
+
+        // model convertion: identity function.
+
+        if (!instantiated) {
+            dealloc(result);
+            result = 0;
+        }
+        return result;
+    }
+
+
+};
+
+
diff --git a/src/muz_qe/dl_mk_quantifier_instantiation.h b/src/muz_qe/dl_mk_quantifier_instantiation.h
new file mode 100644
index 000000000..138d5abee
--- /dev/null
+++ b/src/muz_qe/dl_mk_quantifier_instantiation.h
@@ -0,0 +1,136 @@
+/*++
+Copyright (c) 2013 Microsoft Corporation
+
+Module Name:
+
+    dl_mk_quantifier_instantiation.h
+
+Abstract:
+
+    Convert Quantified Horn clauses into non-quantified clauses using
+    instantiation.
+
+Author:
+
+    Ken McMillan 
+    Andrey Rybalchenko
+    Nikolaj Bjorner (nbjorner) 2013-04-02
+
+Revision History:
+
+    Based on approach suggested in the SAS 2013 paper 
+    "On Solving Universally Quantified Horn Clauses"    
+
+--*/
+#ifndef _DL_MK_QUANTIFIER_INSTANTIATION_H_
+#define _DL_MK_QUANTIFIER_INSTANTIATION_H_
+
+
+#include"dl_rule_transformer.h"
+#include"expr_safe_replace.h"
+
+
+namespace datalog {
+
+    class context;
+
+    class mk_quantifier_instantiation : public rule_transformer::plugin {
+        typedef svector<std::pair<expr*,expr*> > term_pairs;
+
+        class union_find {
+            unsigned_vector   m_find;
+            unsigned_vector   m_size;
+            unsigned_vector   m_next;
+
+            void ensure_size(unsigned v) {
+                while (v >= get_num_vars()) {
+                    mk_var();
+                }
+            }
+        public:
+            unsigned mk_var() {
+                unsigned r = m_find.size();
+                m_find.push_back(r);
+                m_size.push_back(1);
+                m_next.push_back(r);
+                return r;
+            }
+            unsigned get_num_vars() const { return m_find.size(); }
+            
+            unsigned find(unsigned v) const {
+                if (v >= get_num_vars()) {
+                    return v;
+                }
+                while (true) {
+                    unsigned new_v = m_find[v];
+                    if (new_v == v)
+                        return v;
+                    v = new_v;
+                }
+            }
+            
+            unsigned next(unsigned v) const { 
+                if (v >= get_num_vars()) {
+                    return v;
+                }
+                return m_next[v]; 
+            }
+            
+            bool is_root(unsigned v) const { 
+                return v >= get_num_vars() || m_find[v] == v; 
+            }
+            
+            void merge(unsigned v1, unsigned v2) {
+                unsigned r1 = find(v1);
+                unsigned r2 = find(v2);
+                if (r1 == r2)
+                    return;
+                ensure_size(v1);
+                ensure_size(v2);
+                if (m_size[r1] > m_size[r2])
+                    std::swap(r1, r2);
+                m_find[r1] = r2;
+                m_size[r2] += m_size[r1];
+                std::swap(m_next[r1], m_next[r2]);
+            }
+
+            void reset() {
+                m_find.reset();
+                m_next.reset();
+                m_size.reset();
+            }
+        };
+
+        ast_manager&      m;
+        context&          m_ctx;
+        expr_safe_replace m_var2cnst; 
+        expr_safe_replace m_cnst2var;
+        union_find        m_uf;
+        ptr_vector<expr>  m_todo;
+        ptr_vector<expr>  m_terms;
+        ptr_vector<expr>  m_binding;
+        obj_map<func_decl, ptr_vector<expr>*> m_funs;
+
+
+        void extract_quantifiers(rule& r, expr_ref_vector& conjs, quantifier_ref_vector& qs);
+        void collect_egraph(expr* e);
+        void instantiate_rule(rule& r, expr_ref_vector& conjs, quantifier_ref_vector& qs, rule_set& rules);
+        void instantiate_quantifier(quantifier* q, expr_ref_vector & conjs);
+        void instantiate_quantifier(quantifier* q, app* pat, expr_ref_vector & conjs);
+        void match(unsigned i, app* pat, unsigned j, term_pairs& todo, quantifier* q, expr_ref_vector& conjs);
+        void yield_binding(quantifier* q, expr_ref_vector& conjs);
+
+    public:
+        mk_quantifier_instantiation(context & ctx, unsigned priority);
+
+        virtual ~mk_quantifier_instantiation();
+        
+        rule_set * operator()(rule_set const & source);
+    };
+
+
+
+};
+
+#endif /* _DL_MK_QUANTIFIER_INSTANTIATION_H_ */
+