/*++
  Copyright (c) 2011 Microsoft Corporation

  Module Name:

  iz3translate_direct.cpp

  Abstract:

  Translate a Z3 proof into the interpolating proof calculus.
  Translation is direct, without transformations on the target proof
  representation.

  Author:

  Ken McMillan (kenmcmil)

  Revision History:

  --*/


#ifdef _WINDOWS
#pragma warning(disable:4996)
#pragma warning(disable:4800)
#pragma warning(disable:4267)
#pragma warning(disable:4101)
#pragma warning(disable:4390)
#endif

#include "interp/iz3translate.h"
#include "interp/iz3proof.h"
#include "interp/iz3profiling.h"
#include "interp/iz3interp.h"

#include <assert.h>
#include <algorithm>
#include <stdio.h>
#include <fstream>
#include <sstream>
#include <iostream>
#include <set>

//using std::vector;
using namespace stl_ext;

/* This can introduce an address dependency if the range type of hash_map has
   a destructor. Since the code in this file is not used and only here for
   historical comparisons, we allow this non-determinism.
*/
namespace stl_ext {
    template <class T>
    class hash<T *> {
    public:
        size_t operator()(const T *p) const {
            return (size_t) p;
        }
    };
}

static int lemma_count = 0;
#if 0
static int nll_lemma_count = 0;
#endif
#define SHOW_LEMMA_COUNT -1

// One half of a resolution. We need this to distinguish
// between resolving as a clause and as a unit clause.
// if pivot == conclusion(proof) it is unit.

struct Z3_resolvent {
    iz3base::ast proof;
    bool is_unit;
    iz3base::ast pivot;
    Z3_resolvent(const iz3base::ast &_proof,  bool _is_unit, const iz3base::ast &_pivot){
        proof = _proof;
        is_unit = _is_unit;
        pivot = _pivot;
    }
};

namespace hash_space {
    template <>
    class hash<Z3_resolvent > {
    public:
        size_t operator()(const Z3_resolvent &p) const {
            return (p.proof.hash() + p.pivot.hash());
        }
    };
}


bool operator==(const Z3_resolvent &x, const Z3_resolvent &y) {
    return x.proof == y.proof && x.pivot == y.pivot;
}



typedef std::vector<Z3_resolvent *> ResolventAppSet;

struct non_local_lits {
    ResolventAppSet proofs; // the proof nodes being raised
    non_local_lits(ResolventAppSet &_proofs){
        proofs.swap(_proofs);
    }
};

namespace hash_space {
    template <>
    class hash<non_local_lits > {
    public:
        size_t operator()(const non_local_lits &p) const {
            size_t h = 0;
            for(ResolventAppSet::const_iterator it = p.proofs.begin(), en = p.proofs.end(); it != en; ++it)
                h += (size_t)*it;
            return h;
        }
    };
}


bool operator==(const non_local_lits &x, const non_local_lits &y) {
    ResolventAppSet::const_iterator itx = x.proofs.begin();
    ResolventAppSet::const_iterator ity = y.proofs.begin();
    while(true){
        if(ity == y.proofs.end()) return itx == x.proofs.end();
        if(itx == x.proofs.end()) return ity == y.proofs.end();
        if(*itx != *ity) return false;
        ++itx; ++ity;
    }
}


/* This translator goes directly from Z3 proofs to interpolatable
   proofs without an intermediate representation as an iz3proof. */

class iz3translation_direct : public iz3translation {
public:

    typedef ast Zproof;   // type of non-interpolating proofs
    typedef iz3proof Iproof; // type of interpolating proofs
  
    /* Here we have lots of hash tables for memoizing various methods and
       other such global data structures.
    */

    typedef hash_map<ast,int> AstToInt;
    AstToInt locality;                        // memoizes locality of Z3 proof terms

    typedef std::pair<ast,ast> EquivEntry;
    typedef hash_map<ast,EquivEntry> EquivTab;
    EquivTab equivs;                          // maps non-local terms to equivalent local terms, with proof

    typedef hash_set<ast> AstHashSet;
    AstHashSet equivs_visited;                // proofs already checked for equivalences


    typedef std::pair<hash_map<ast,Iproof::node>, hash_map<ast,Iproof::node> > AstToIpf;
    AstToIpf translation;                     // Zproof nodes to Iproof nodes
  
    AstHashSet antes_added;                   // Z3 proof terms whose antecedents have been added to the list
    std::vector<std::pair<ast,int> > antes;   // list of antecedent/frame pairs
    std::vector<ast> local_antes;                       // list of local antecedents

    Iproof *iproof;                            // the interpolating proof we are constructing

    int frames;                               // number of frames

    typedef std::set<ast> AstSet;
    typedef hash_map<ast,AstSet> AstToAstSet;
    AstToAstSet hyp_map;                      // map proof terms to hypothesis set

    struct LocVar {                           // localization vars
        ast var;                                // a fresh variable
        ast term;                               // term it represents
        int frame;                              // frame in which it's defined
        LocVar(ast v, ast t, int f){var=v;term=t;frame=f;}
    };

    std::vector<LocVar> localization_vars;         // localization vars in order of creation
    typedef hash_map<ast,ast> AstToAst;
    AstToAst localization_map;                // maps terms to their localization vars

    typedef hash_map<ast,bool> AstToBool;



    iz3secondary *secondary;                // the secondary prover

    // Unique table for sets of non-local resolutions
    hash_map<non_local_lits, non_local_lits *> non_local_lits_unique;

    // Unique table for resolvents
    hash_map<Z3_resolvent, Z3_resolvent *> Z3_resolvent_unique;

    // Translation memo for case of non-local resolutions
    hash_map<non_local_lits *, AstToIpf> non_local_translation;

public:

 
#define from_ast(x) (x)

    // determine locality of a proof term
    // return frame of derivation if local, or -1 if not
    // result INT_MAX means the proof term is a tautology
    // memoized in hash_map "locality"

    int get_locality_rec(ast proof){
        std::pair<ast,int> foo(proof,INT_MAX);
        std::pair<AstToInt::iterator, bool> bar = locality.insert(foo);
        int &res = bar.first->second;
        if(!bar.second) return res;
        if(pr(proof) == PR_ASSERTED){
            ast ass = conc(proof);
            res = frame_of_assertion(ass);
        }
        else {
            unsigned nprems = num_prems(proof);
            for(unsigned i = 0; i < nprems; i++){
                ast arg = prem(proof,i);
                int bar = get_locality_rec(arg);
                if(res == INT_MAX || res == bar) res = bar;
                else if(bar != INT_MAX) res = -1;
            }
        }
        return res;
    }


    int get_locality(ast proof){
        // if(lia_z3_axioms_only) return -1;
        int res = get_locality_rec(proof);
        if(res != -1){
            ast con = conc(proof);
            range rng = ast_scope(con);

            // hack: if a clause contains "true", it reduces to "true",
            // which means we won't compute the range correctly. we handle
            // this case by computing the ranges of the literals separately

            if(is_true(con)){
                std::vector<ast> lits;
                get_Z3_lits(conc(proof),lits);
                for(unsigned i = 0; i < lits.size(); i++)
                    rng = range_glb(rng,ast_scope(lits[i]));
            }
      
            if(!range_is_empty(rng)){
                AstSet &hyps = get_hyps(proof);
                for(AstSet::iterator it = hyps.begin(), en = hyps.end(); it != en; ++it){
                    ast hyp = *it;
                    rng = range_glb(rng,ast_scope(hyp));
                }
            }

            if(res == INT_MAX){
                if(range_is_empty(rng))
                    res = -1;
                else res = range_max(rng);
            }
            else {
                if(!in_range(res,rng))
                    res = -1;
            }
        }
        return res;
    }

    AstSet &get_hyps(ast proof){
        std::pair<ast,AstSet > foo(proof,AstSet());
        std::pair<AstToAstSet::iterator, bool> bar = hyp_map.insert(foo);
        AstSet &res = bar.first->second;
        if(!bar.second) return res;
        pfrule dk = pr(proof);
        if(dk == PR_HYPOTHESIS){
            ast con = conc(proof);
            res.insert(con);
        }
        else {
            unsigned nprems = num_prems(proof);
            for(unsigned i = 0; i < nprems; i++){
                ast arg = prem(proof,i);
                AstSet &arg_hyps = get_hyps(arg);
                res.insert(arg_hyps.begin(),arg_hyps.end());
            }
            if(dk == PR_LEMMA){
                ast con = conc(proof);
                res.erase(mk_not(con));
                if(is_or(con)){
                    int clause_size = num_args(con);
                    for(int i = 0; i < clause_size; i++){
                        ast neglit = mk_not(arg(con,i));
                        res.erase(neglit);
                    }
                }        
            }
        }
#if 0
        AstSet::iterator it = res.begin(), en = res.end();
        if(it != en){
            AstSet::iterator old = it;
            ++it;
            for(; it != en; ++it, ++old)
                if(!(*old < *it))
                    std::cout << "foo!";
        }
#endif
        return res;
    }


    // Find all the judgements of the form p <-> q, where
    // p is local and q is non-local, recording them in "equivs"
    // the map equivs_visited is used to record the already visited proof terms

    void find_equivs(ast proof){
        if(equivs_visited.find(proof) != equivs_visited.end())
            return;
        equivs_visited.insert(proof);
        unsigned nprems = num_prems(proof);
        for(unsigned i = 0; i < nprems; i++) // do all the sub_terms
            find_equivs(prem(proof,i));
        ast con = conc(proof); // get the conclusion
        if(is_iff(con)){
            ast iff = con;
            for(int i = 0; i < 2; i++)
                if(!is_local(arg(iff,i)) && is_local(arg(iff,1-i))){
                    std::pair<ast,std::pair<ast,ast> > foo(arg(iff,i),std::pair<ast,ast>(arg(iff,1-i),proof));
                    equivs.insert(foo);
                }
        }
    }

    // get the lits of a Z3 clause as secondary prover terms
    void get_Z3_lits(ast t, std::vector<ast> &lits){
        opr dk = op(t);
        if(dk == False)
            return; // false = empty clause
        if(dk == Or){
            unsigned nargs = num_args(t);
            lits.resize(nargs);
            for(unsigned i = 0; i < nargs; i++) // do all the sub_terms
                lits[i] = arg(t,i);
        }
        else {
            lits.push_back(t);
        }
    }

    // resolve two clauses represented as vectors of lits. replace first clause
    void resolve(ast pivot, std::vector<ast> &cls1, std::vector<ast> &cls2){
        ast neg_pivot = mk_not(pivot);
        for(unsigned i = 0; i < cls1.size(); i++){
            if(cls1[i] == pivot){
                cls1[i] = cls1.back();
                cls1.pop_back();
                bool found_pivot2 = false;
                for(unsigned j = 0; j < cls2.size(); j++){
                    if(cls2[j] == neg_pivot)
                        found_pivot2 = true;
                    else
                        cls1.push_back(cls2[j]);
                }
                (void)found_pivot2;
                assert(found_pivot2);
                return;
            }
        }
        assert(0 && "resolve failed");
    }

    // get lits resulting from unit resolution up to and including "position"
    // TODO: this is quadratic -- fix it
    void do_unit_resolution(ast proof, int position, std::vector<ast> &lits){
        ast orig_clause = conc(prem(proof,0));
        get_Z3_lits(orig_clause,lits);
        for(int i = 1; i <= position; i++){
            std::vector<ast> unit(1);
            unit[0] = conc(prem(proof,i));
            resolve(mk_not(unit[0]),lits,unit);
        }
    }
  

    // clear the localization variables
    void clear_localization(){
        localization_vars.clear();
        localization_map.clear();
    }
  
    // create a fresh variable for localization
    ast fresh_localization_var(ast term, int frame){
        std::ostringstream s;
        s << "%" << (localization_vars.size());
        ast var = make_var(s.str().c_str(),get_type(term));
        sym_range(sym(var)) = range_full(); // make this variable global
        localization_vars.push_back(LocVar(var,term,frame));
        return var;
    }
  

    // "localize" a term to a given frame range by 
    // creating new symbols to represent non-local subterms

    ast localize_term(ast e, const range &rng){
        if(ranges_intersect(ast_scope(e),rng))
            return e; // this term occurs in range, so it's O.K.
        AstToAst::iterator it = localization_map.find(e);
        if(it != localization_map.end())
            return it->second;

        // if is is non-local, we must first localize the arguments to
        // the range of its function symbol
    
        int nargs = num_args(e);
        if(nargs > 0 /*  && (!is_local(e) || flo <= hi || fhi >= lo) */){
            range frng = rng;
            if(op(e) == Uninterpreted){
                symb f = sym(e);
                range srng = sym_range(f);
                if(ranges_intersect(srng,rng)) // localize to desired range if possible
                    frng = range_glb(srng,rng);
            }
            std::vector<ast> largs(nargs);
            for(int i = 0; i < nargs; i++){
                largs[i] = localize_term(arg(e,i),frng);
                frng = range_glb(frng,ast_scope(largs[i]));
            }
            e = clone(e,largs);
            assert(is_local(e));
        }


        if(ranges_intersect(ast_scope(e),rng))
            return e; // this term occurs in range, so it's O.K.

        // choose a frame for the constraint that is close to range
        int frame = range_near(ast_scope(e),rng);

        ast new_var = fresh_localization_var(e,frame);
        localization_map[e] = new_var;
        ast cnst = make(Equal,new_var,e);
        antes.push_back(std::pair<ast,int>(cnst,frame));
        return new_var;
    }

    // some patterm matching functions

    // match logical or with nargs arguments
    // assumes AIG form
    bool match_or(ast e, ast *args, int nargs){
        if(op(e) != Or) return false;
        int n = num_args(e);
        if(n != nargs) return false;
        for(int i = 0; i < nargs; i++)
            args[i] = arg(e,i);
        return true;
    }

    // match operator f with exactly nargs arguments
    bool match_op(ast e, opr f, ast *args, int nargs){
        if(op(e) != f) return false;
        int n = num_args(e);
        if(n != nargs) return false;
        for(int i = 0; i < nargs; i++)
            args[i] = arg(e,i);
        return true;
    }

    // see if the given formula can be interpreted as
    // an axiom instance (e.g., an array axiom instance).
    // if so, add it to "antes" in an appropriate frame.
    // this may require "localization"
  
    void get_axiom_instance(ast e){

        // "store" axiom
        // (or (= w q) (= (select (store a1 w y) q) (select a1 q)))
        // std::cout << "ax: "; show(e);
        ast lits[2],eq_ops_l[2],eq_ops_r[2],sel_ops[2], sto_ops[3], sel_ops2[2] ; 
        if(match_or(e,lits,2))
            if(match_op(lits[0],Equal,eq_ops_l,2))
                if(match_op(lits[1],Equal,eq_ops_r,2))
                    for(int i = 0; i < 2; i++){ // try the second equality both ways
                        if(match_op(eq_ops_r[0],Select,sel_ops,2))
                            if(match_op(sel_ops[0],Store,sto_ops,3))
                                if(match_op(eq_ops_r[1],Select,sel_ops2,2))
                                    for(int j = 0; j < 2; j++){ // try the first equality both ways
                                        if(eq_ops_l[0] == sto_ops[1]
                                           && eq_ops_l[1] == sel_ops[1]
                                           && eq_ops_l[1] == sel_ops2[1]
                                           && sto_ops[0] == sel_ops2[0])
                                            if(is_local(sel_ops[0])) // store term must be local
                                                {    
                                                    ast sto = sel_ops[0];
                                                    ast addr = localize_term(eq_ops_l[1],ast_scope(sto));
                                                    ast res = make(Or,
                                                                   make(Equal,eq_ops_l[0],addr),
                                                                   make(Equal,
                                                                        make(Select,sto,addr),
                                                                        make(Select,sel_ops2[0],addr)));
                                                    int frame = range_min(ast_scope(res));
                                                    antes.push_back(std::pair<ast,int>(res,frame));
                                                    return;
                                                }
                                        std::swap(eq_ops_l[0],eq_ops_l[1]);
                                    }
                        std::swap(eq_ops_r[0],eq_ops_r[1]);
                    }
    }

    // a quantifier instantation looks like (~ forall x. P) \/ P[z/x]
    // we need to find a time frame for P, then localize P[z/x] in this frame

    void get_quantifier_instance(ast e){
        ast disjs[2];
        if(match_or(e,disjs,2)){
            if(is_local(disjs[0])){
                ast res = localize_term(disjs[1], ast_scope(disjs[0]));
                int frame = range_min(ast_scope(res));
                antes.push_back(std::pair<ast,int>(res,frame));
                return;
            }
        }
    }

    ast get_judgement(ast proof){
        ast con = from_ast(conc(proof));
        AstSet &hyps = get_hyps(proof);
        std::vector<ast> hyps_vec;
        for(AstSet::iterator it = hyps.begin(), en = hyps.end(); it != en; ++it)
            hyps_vec.push_back(*it);
        if(hyps_vec.size() == 0) return con;
        con = make(Or,mk_not(make(And,hyps_vec)),con);
        return con;
    }

    // add the premises of a proof term to the "antes" list

    void add_antes(ast proof){
        if(antes_added.find(proof) != antes_added.end()) return;
        antes_added.insert(proof);
        int frame = get_locality(proof);
        if(frame != -1)
            if(1){
                ast e = get_judgement(proof);
                if(frame >= frames) frame = frames-1; // can happen if there are no symbols
                antes.push_back(std::pair<ast,int>(e,frame));
                return;
            }
        pfrule dk = pr(proof);
        if(dk == PR_ASSERTED){
            ast ass = conc(proof);
            frame = frame_of_assertion(ass);
            if(frame >= frames) frame = frames-1; // can happen if a theory fact
            antes.push_back(std::pair<ast,int>(ass,frame));
            return;
        }
        if(dk == PR_TH_LEMMA && num_prems(proof) == 0){
            get_axiom_instance(conc(proof));
        }
        if(dk == PR_QUANT_INST && num_prems(proof) == 0){
            get_quantifier_instance(conc(proof));
        }
        unsigned nprems = num_prems(proof);
        for(unsigned i = 0; i < nprems; i++){
            ast arg = prem(proof,i);
            add_antes(arg);
        }    
    }


    // add quantifiers over the localization vars
    // to an interpolant for frames lo-hi

    ast add_quants(ast e, int lo, int hi){
        for(int i = localization_vars.size() - 1; i >= 0; i--){
            LocVar &lv = localization_vars[i];
            opr quantifier = (lv.frame >= lo && lv.frame <= hi) ? Exists : Forall; 
            e = apply_quant(quantifier,lv.var,e);
        }
        return e;
    }

    int get_lits_locality(std::vector<ast> &lits){
        range rng = range_full();
        for(std::vector<ast>::iterator it = lits.begin(), en = lits.end(); it != en; ++it){
            ast lit = *it;
            rng = range_glb(rng,ast_scope(lit));
        }
        if(range_is_empty(rng)) return -1;
    int hi = range_max(rng);
        if(hi >= frames) return frames - 1;
        return hi;
    }


    struct invalid_lemma: public iz3_exception {
        invalid_lemma(): iz3_exception("invalid_lemma") {}
    };




    // prove a lemma (clause) using current antes list
    // return proof of the lemma
    // use the secondary prover

    int prove_lemma(std::vector<ast> &lits){
    

        // first try localization
        if(antes.size() == 0){
            int local_frame = get_lits_locality(lits);
            if(local_frame != -1)
                return iproof->make_assumption(local_frame,lits); // no proof needed for purely local fact
        }

        // group the assumptions by frame
        std::vector<ast> preds(frames);
        for(unsigned i = 0; i < preds.size(); i++)
            preds[i] = mk_true();
        for(unsigned i = 0; i < antes.size(); i++){
            int frame = antes[i].second;
            preds[frame] = mk_and(preds[frame],antes[i].first); // conjoin it to frame
        }

        for(unsigned i = 0; i < lits.size(); i++){
            int frame;
            if(!weak_mode()){
                frame = range_max(ast_scope(lits[i]));
                if(frame >= frames) frame = frames-1; // could happen if contains no symbols
            }
            else {
                frame = range_min(ast_scope(lits[i]));
                if(frame < 0){
                    frame = range_max(ast_scope(lits[i])); // could happen if contains no symbols
                    if(frame >= frames) frame = frames-1; 
                }
            }
            preds[frame] = mk_and(preds[frame],mk_not(lits[i]));
        }


        std::vector<ast> itps; // holds interpolants


#if 1
        ++lemma_count;
        // std::cout << "lemma: " << lemma_count << std::endl;
        if(lemma_count == SHOW_LEMMA_COUNT){
            for(unsigned i = 0; i < lits.size(); i++)
                show_lit(lits[i]);
            std::cerr << "lemma written to file lemma.smt:\n";
            iz3base foo(*this,preds,std::vector<int>(),std::vector<ast>());
            foo.print("lemma.smt");
            throw invalid_lemma();
        }
#endif

#if 0
        std::cout << "\nLemma:\n";
        for(unsigned i = 0; i < lits.size(); i++)
            show_lit(lits[i]);
#endif 

        // interpolate using secondary prover
        profiling::timer_start("secondary prover");
        int sat = secondary->interpolate(preds,itps);
        profiling::timer_stop("secondary prover");

        std::cout << "lemma done" << std::endl;

        // if sat, lemma isn't valid, something is wrong
        if(sat){
#if 1
            std::cerr << "invalid lemma written to file invalid_lemma.smt:\n";
            iz3base foo(*this,preds,std::vector<int>(),std::vector<ast>());
            foo.print("invalid_lemma.smt");
#endif
            throw iz3_incompleteness();
        }
        assert(sat == 0); // if sat, lemma doesn't hold!

        // quantifiy the localization vars
        for(unsigned i = 0; i < itps.size(); i++)
            itps[i] = add_quants(itps[i],0,i);
    
        // Make a lemma, storing interpolants
        Iproof::node res = iproof->make_lemma(lits,itps);

#if 0
        std::cout << "Lemma interps\n";
        for(unsigned i = 0; i < itps.size(); i++)
            show(itps[i]);
#endif    

        // Reset state for the next lemma
        antes.clear();
        antes_added.clear();
        clear_localization(); // use a fresh localization for each lemma

        return res;
    }

    // sanity check: make sure that any non-local lit is really resolved
    // with something in the non_local_lits set

    void check_non_local(ast lit, non_local_lits *nll){
        if(nll)
            for(ResolventAppSet::iterator it = nll->proofs.begin(), en = nll->proofs.end(); it != en; ++it){
                ast con = (*it)->pivot;
                if(con == mk_not(lit)) return;
            }
        assert(0 && "bug in non-local resolution handling");
    }


    void get_local_conclusion_lits(ast proof, bool expect_clause, AstSet &lits){
        std::vector<ast> reslits;
        if(expect_clause)
            get_Z3_lits(conc(proof),reslits);
        else reslits.push_back(conc(proof));
        for(unsigned i = 0; i < reslits.size(); i++)
            if(is_local(reslits[i]))
                lits.insert(reslits[i]);
        AstSet &pfhyps = get_hyps(proof);
        for(AstSet::iterator hit = pfhyps.begin(), hen = pfhyps.end(); hit != hen; ++hit)
            if(is_local(*hit))
                lits.insert(mk_not(*hit));
    }


    void collect_resolvent_lits(Z3_resolvent *res, const AstSet &hyps, std::vector<ast> &lits){
        if(!res->is_unit){
            std::vector<ast> reslits;
            get_Z3_lits(conc(res->proof),reslits);
            for(unsigned i = 0; i < reslits.size(); i++)
                if(reslits[i] != res->pivot)
                    lits.push_back(reslits[i]);
        }
        AstSet &pfhyps = get_hyps(res->proof);
        for(AstSet::iterator hit = pfhyps.begin(), hen = pfhyps.end(); hit != hen; ++hit)
            if(hyps.find(*hit) == hyps.end())
                lits.push_back(mk_not(*hit));
    }

    void filter_resolvent_lits(non_local_lits *nll, std::vector<ast> &lits){
        std::vector<ast> orig_lits; orig_lits.swap(lits);
        std::set<ast> pivs;
        for(ResolventAppSet::iterator it = nll->proofs.begin(), en = nll->proofs.end(); it != en; ++it){
            Z3_resolvent *res = *it;
            pivs.insert(res->pivot);
            pivs.insert(mk_not(res->pivot));
        }
        for(unsigned i = 0; i < orig_lits.size(); i++)
            if(pivs.find(orig_lits[i]) == pivs.end())
                lits.push_back(orig_lits[i]);
    }

    void collect_all_resolvent_lits(non_local_lits *nll, std::vector<ast> &lits){
        if(nll){
            std::vector<ast> orig_lits; orig_lits.swap(lits);
            std::set<ast> pivs;
            for(ResolventAppSet::iterator it = nll->proofs.begin(), en = nll->proofs.end(); it != en; ++it){
                Z3_resolvent *res = *it;
                pivs.insert(res->pivot);
                pivs.insert(mk_not(res->pivot));
            }
            for(ResolventAppSet::iterator it = nll->proofs.begin(), en = nll->proofs.end(); it != en; ++it){
                Z3_resolvent *res = *it;
                {
                    std::vector<ast> reslits;
                    if(!res->is_unit) get_Z3_lits(conc(res->proof),reslits);
                    else reslits.push_back(conc(res->proof));
                    for(unsigned i = 0; i < reslits.size(); i++)
#if 0
                        if(reslits[i] != res->pivot && pivs.find(reslits[i]) == pivs.end())
#endif
                            if(is_local(reslits[i]))
                                lits.push_back(reslits[i]);
                }
            }
            for(unsigned i = 0; i < orig_lits.size(); i++)
                if(pivs.find(orig_lits[i]) == pivs.end())
                    lits.push_back(orig_lits[i]);
        }
    }

    void collect_proof_clause(ast proof, bool expect_clause, std::vector<ast> &lits){
        if(expect_clause)
            get_Z3_lits(conc(proof),lits);
        else
            lits.push_back(from_ast(conc(proof)));
        AstSet &hyps = get_hyps(proof);
        for(AstSet::iterator hit = hyps.begin(), hen = hyps.end(); hit != hen; ++hit)
            lits.push_back(mk_not(*hit));
    }


    // turn a bunch of literals into a lemma, replacing
    // non-local lits with their local equivalents
    // adds the accumulated antecedents (antes) as
    // proof obligations of the lemma

    Iproof::node fix_lemma(std::vector<ast> &con_lits, AstSet &hyps, non_local_lits *nll){
        std::vector<ast> lits(con_lits);
        for(AstSet::iterator it = hyps.begin(), en = hyps.end(); it != en; ++it)
            lits.push_back(mk_not(*it));
        if(nll){
            for(ResolventAppSet::iterator it = nll->proofs.begin(), en = nll->proofs.end(); it != en; ++it){
                Z3_resolvent *res = *it;
                collect_resolvent_lits(res,hyps,lits);
                add_antes(res->proof);
            }
            filter_resolvent_lits(nll,lits);
        }
        for(unsigned int i = 0; i < lits.size(); i++){
            EquivTab::iterator it = equivs.find(lits[i]);
            if(it != equivs.end()){
                lits[i] = it->second.first;  // replace with local equivalent
                add_antes(it->second.second); // collect the premises that prove this
            }
            else {
                if(!is_local(lits[i])){
                    check_non_local(lits[i],nll);
                    lits[i] = mk_false();
                }
            }
        }
        // TODO: should check here that derivation is local?
        Iproof::node res = prove_lemma(lits);
        return res;
    }

    int num_lits(ast ast){
        opr dk = op(ast);
        if(dk == False)
            return 0;
        if(dk == Or){
            unsigned nargs = num_args(ast);
            int n = 0;
            for(unsigned i = 0; i < nargs; i++) // do all the sub_terms
                n += num_lits(arg(ast,i));
            return n;
        }
        else 
            return 1;
    }

    struct non_lit_local_ante: public iz3_exception {
        non_lit_local_ante(): iz3_exception("non_lit_local_ante") {}
    };

    bool local_antes_simple;

    bool add_local_antes(ast proof, AstSet &hyps, bool expect_clause = false){
        if(antes_added.find(proof) != antes_added.end()) return true;
        antes_added.insert(proof);
        ast con = from_ast(conc(proof));
        pfrule dk = pr(proof);
        if(is_local(con) || equivs.find(con) != equivs.end()){
            if(!expect_clause || num_lits(conc(proof)) == 1){
                AstSet &this_hyps = get_hyps(proof);
                if(std::includes(hyps.begin(),hyps.end(),this_hyps.begin(),this_hyps.end())){
                    // if(hyps.find(con) == hyps.end())
#if 0
                    if(/* lemma_count == SHOW_LEMMA_COUNT - 1 && */ !is_literal_or_lit_iff(conc(proof))){
                        std::cout << "\nnon-lit local ante\n";
                        show_step(proof);
                        show(conc(proof));
                        throw non_lit_local_ante();
                    }
#endif
                    local_antes.push_back(proof);
                    return true;
                }
                else
                    ; //std::cout << "bar!\n";
            }
        }
        if(dk == PR_ASSERTED
           //|| dk == PR_HYPOTHESIS
           //|| dk == PR_TH_LEMMA
           || dk == PR_QUANT_INST
           //|| dk == PR_UNIT_RESOLUTION
           //|| dk == PR_LEMMA
       )
            return false;
        if(dk == PR_HYPOTHESIS && hyps.find(con) != hyps.end())
            ; //std::cout << "blif!\n";
        if(dk == PR_HYPOTHESIS
           || dk == PR_LEMMA)
            ; //std::cout << "foo!\n";
        if(dk == PR_TH_LEMMA && num_prems(proof) == 0){
            // Check if this is an axiom instance
            get_axiom_instance(conc(proof));
        }

        // #define SIMPLE_PROOFS    
#ifdef SIMPLE_PROOFS
        if(!(dk == PR_TRANSITIVITY
             || dk == PR_MONOTONICITY))
            local_antes_simple = false;
#endif

        unsigned nprems = num_prems(proof);
        for(unsigned i = 0; i < nprems; i++){
            ast arg = prem(proof,i);
            try {
                if(!add_local_antes(arg, hyps, dk == PR_UNIT_RESOLUTION && i == 0))
                    return false;
            }
            catch (const non_lit_local_ante &) {
                std::cout << "\n";
                show_step(proof);
                show(conc(proof));
                throw non_lit_local_ante();
            }
        }
        return true;
    }

    std::vector<ast> lit_trace;
    hash_set<ast> marked_proofs;

    bool proof_has_lit(const ast &proof, const ast &lit){
        AstSet &hyps = get_hyps(proof);
        if(hyps.find(mk_not(lit)) != hyps.end())
            return true;
        std::vector<ast> lits;
        ast con = conc(proof);
        get_Z3_lits(con, lits);
        for(unsigned i = 0; i < lits.size(); i++)
            if(lits[i] == lit)
                return true;
        return false;
    }


    void trace_lit_rec(const ast &lit, const ast &proof, AstHashSet &memo){
        if(memo.find(proof) == memo.end()){
            memo.insert(proof);
            AstSet &hyps = get_hyps(proof);
            std::vector<ast> lits;
            for(AstSet::iterator it = hyps.begin(), en = hyps.end(); it != en; ++it)
                lits.push_back(mk_not(*it));
            ast con = conc(proof);
            get_Z3_lits(con, lits);
            for(unsigned i = 0; i < lits.size(); i++){
                if(lits[i] == lit){
                    print_expr(std::cout,proof);
                    std::cout << "\n";
                    marked_proofs.insert(proof);
                    pfrule dk = pr(proof);
                    if(dk == PR_UNIT_RESOLUTION || dk == PR_LEMMA){
                        unsigned nprems = num_prems(proof);
                        for(unsigned i = 0; i < nprems; i++){
                            ast arg = prem(proof,i);
                            trace_lit_rec(lit,arg,memo);
                        }
                    }
                    else
                        lit_trace.push_back(proof);
                }
            }
        }
    }
  
    ast traced_lit;

    int trace_lit(const ast &lit, const ast &proof){
        marked_proofs.clear();
        lit_trace.clear();
        traced_lit = lit;
        AstHashSet memo;
        trace_lit_rec(lit,proof,memo);
        return lit_trace.size();
    }

    bool is_literal_or_lit_iff(const ast &lit){
        if(my_is_literal(lit)) return true;
        if(op(lit) == Iff){
            return my_is_literal(arg(lit,0)) && my_is_literal(arg(lit,1));
        }
        return false;
    }

    bool my_is_literal(const ast &lit){
        ast abslit = is_not(lit) ? arg(lit,0) : lit;
        int f = op(abslit);
        return !(f == And || f == Or || f == Iff);
    }

    void print_lit(const ast &lit){
        ast abslit = is_not(lit) ? arg(lit,0) : lit;
        if(!is_literal_or_lit_iff(lit)){
            if(is_not(lit)) std::cout << "~";
            std::cout << "[";
            print_expr(std::cout,abslit);
            std::cout << "]";
        }
        else
            print_expr(std::cout,lit);
    }

    void show_lit(const ast &lit){
        print_lit(lit);
        std::cout << "\n";
    }

    void print_z3_lit(const ast &a){
        print_lit(from_ast(a));
    }

    void show_z3_lit(const ast &a){
        print_z3_lit(a);
        std::cout << "\n";
    }

  
    void show_con(const ast &proof, bool brief){
        if(!traced_lit.null() && proof_has_lit(proof,traced_lit))
            std::cout << "(*) ";
        ast con = conc(proof);
        AstSet &hyps = get_hyps(proof);
        int count = 0;
        for(AstSet::iterator it = hyps.begin(), en = hyps.end(); it != en; ++it){
            if(brief && ++count > 5){
                std::cout << "... ";
                break;
            }
            print_lit(*it);
            std::cout << " ";
        }
        std::cout << "|- ";
        std::vector<ast> lits;
        get_Z3_lits(con,lits);
        for(unsigned i = 0; i < lits.size(); i++){
            print_lit(lits[i]);
            std::cout << " ";
        }
        std::cout << "\n";
    }

    void show_step(const  ast &proof){
        std::cout << "\n";
        unsigned nprems = num_prems(proof);
        for(unsigned i = 0; i < nprems; i++){
            std::cout << "(" << i << ") ";
            ast arg = prem(proof,i);
            show_con(arg,true);
        }
        std::cout << "|------ ";
        std::cout << string_of_symbol(sym(proof)) << "\n";
        show_con(proof,false);
    }

    void show_marked( const ast &proof){
        std::cout << "\n";
        unsigned nprems = num_prems(proof);
        for(unsigned i = 0; i < nprems; i++){
            ast arg = prem(proof,i);
            if(!traced_lit.null() && proof_has_lit(arg,traced_lit)){
                std::cout << "(" << i << ") ";
                show_con(arg,true);
            }
        }
    }

    std::vector<ast> pfhist;
    int pfhist_pos;
  
    void pfgoto(const ast &proof){
        if(pfhist.size() == 0)
            pfhist_pos = 0;
        else pfhist_pos++;
        pfhist.resize(pfhist_pos);
        pfhist.push_back(proof);
        show_step(proof);
    }

    void show_nll(non_local_lits *nll){
        if(!nll)return;
        for(ResolventAppSet::iterator it = nll->proofs.begin(), en = nll->proofs.end(); it != en; ++it){
            Z3_resolvent *res = *it;
            show_step(res->proof);
            std::cout << "Pivot: ";
            show(res->pivot);
            std::cout << std::endl;
        }
    }
  
    void pfback(){
        if(pfhist_pos > 0){
            pfhist_pos--;
            show_step(pfhist[pfhist_pos]);
        }
    }

    void pffwd(){
        if(pfhist_pos < ((int)pfhist.size()) - 1){
            pfhist_pos++;
            show_step(pfhist[pfhist_pos]);
        }
    }

    void pfprem(int i){
        if(pfhist.size() > 0){
            ast proof = pfhist[pfhist_pos];
            unsigned nprems = num_prems(proof);
            if(i >= 0 && i < (int)nprems)
                pfgoto(prem(proof,i));
        }
    }

    int extract_th_lemma_common(std::vector<ast> &lits, non_local_lits *nll, bool lemma_nll = true){
        std::vector<ast> la = local_antes;
        local_antes.clear();  // clear antecedents for next lemma
        antes_added.clear();
        // std::vector<int> lits;
        AstSet hyps; // no hyps
        for(unsigned i = 0; i < la.size(); i++)
            lits.push_back(mk_not(from_ast(conc(la[i]))));
        // lits.push_back(from_ast(conc(proof)));
        Iproof::node res =fix_lemma(lits,hyps, lemma_nll ? nll : nullptr);
        for(unsigned i = 0; i < la.size(); i++){
            Iproof::node q = translate_main(la[i],nll,false);
            ast pnode = from_ast(conc(la[i]));
            assert(is_local(pnode) ||  equivs.find(pnode) != equivs.end());
            Iproof::node neg = res;
            Iproof::node pos = q;
            if(is_not(pnode)){
                pnode = mk_not(pnode);
                std::swap(neg,pos);
            }
            try {
                res = iproof->make_resolution(pnode,neg,pos);
            }
            catch (const iz3proof::proof_error &){
                std::cout << "\nresolution error in theory lemma\n";
                std::cout << "lits:\n";
                for(unsigned j = 0; j < lits.size(); j++)
                    show_lit(lits[j]);
                std::cout << "\nstep:\n";
                show_step(la[i]);
                throw invalid_lemma();
            }
        }
        return res;
    }

    Iproof::node extract_simple_proof(const ast &proof, hash_set<ast> &leaves){
        if(leaves.find(proof) != leaves.end())
            return iproof->make_hypothesis(conc(proof));
        ast con = from_ast(conc(proof));
        pfrule dk = pr(proof);
        unsigned nprems = num_prems(proof);
        std::vector<Iproof::node> args(nprems);
        for(unsigned i = 0; i < nprems; i++){
            ast arg = prem(proof,i);
            args[i] = extract_simple_proof(arg,leaves);
        }

        switch(dk){
        case PR_TRANSITIVITY:
            return iproof->make_transitivity(con,args[0],args[1]);
        case PR_MONOTONICITY:
            return iproof->make_congruence(con,args);
        case PR_REFLEXIVITY:
            return iproof->make_reflexivity(con);
        case PR_SYMMETRY:
            return iproof->make_symmetry(con,args[0]);
        }
        assert(0 && "extract_simple_proof: unknown op");
        return 0;
    }

    int extract_th_lemma_simple(const ast &proof, std::vector<ast> &lits){
        std::vector<ast> la = local_antes;
        local_antes.clear();  // clear antecedents for next lemma
        antes_added.clear();

        hash_set<ast> leaves;
        for(unsigned i = 0; i < la.size(); i++)
            leaves.insert(la[i]);
    
        Iproof::node ipf = extract_simple_proof(proof,leaves);
        ast con = from_ast(conc(proof));
        Iproof::node hyp = iproof->make_hypothesis(mk_not(con));
        ipf = iproof->make_eqcontra(ipf,hyp);

        // std::vector<int> lits;
        AstSet hyps; // no hyps
        for(unsigned i = 0; i < la.size(); i++)
            lits.push_back(mk_not(from_ast(conc(la[i]))));
        // lits.push_back(from_ast(conc(proof)));

        Iproof::node res = iproof->make_contra(ipf,lits);

        for(unsigned i = 0; i < la.size(); i++){
            Iproof::node q = translate_main(la[i],nullptr,false);
            ast pnode = from_ast(conc(la[i]));
            assert(is_local(pnode) ||  equivs.find(pnode) != equivs.end());
            Iproof::node neg = res;
            Iproof::node pos = q;
            if(is_not(pnode)){
                pnode = mk_not(pnode);
                std::swap(neg,pos);
            }
            try {
                res = iproof->make_resolution(pnode,neg,pos);
            }
            catch (const iz3proof::proof_error &){
                std::cout << "\nresolution error in theory lemma\n";
                std::cout << "lits:\n";
                for(unsigned j = 0; j < lits.size(); j++)
                    show_lit(lits[j]);
                std::cout << "\nstep:\n";
                show_step(la[i]);
                throw invalid_lemma();
            }
        }
        return res;
    }

    // #define NEW_EXTRACT_TH_LEMMA

    void get_local_hyps(const ast &proof, std::set<ast> &res){
        std::set<ast> hyps = get_hyps(proof);
        for(std::set<ast>::iterator it = hyps.begin(), en = hyps.end(); it != en; ++it){
            ast hyp = *it;
            if(is_local(hyp))
                res.insert(hyp);
        }
    }

    int extract_th_lemma(ast proof, std::vector<ast> &lits, non_local_lits *nll){
        pfrule dk = pr(proof);
        unsigned nprems = num_prems(proof);
#ifdef NEW_EXTRACT_TH_LEMMA
        if(nprems == 0 && !nll)
#else
            if(nprems == 0)
#endif
                return 0;
        if(nprems == 0 && dk == PR_TH_LEMMA)
            // Check if this is an axiom instance
            get_axiom_instance(conc(proof));

        local_antes_simple = true;
        for(unsigned i = 0; i < nprems; i++){
            ast arg = prem(proof,i);
            if(!add_local_antes(arg,get_hyps(proof))){
                local_antes.clear();  // clear antecedents for next lemma
                antes_added.clear();
                antes.clear();
                return 0;
            }
        }
#ifdef NEW_EXTRACT_TH_LEMMA
        bool lemma_nll = nprems > 1;
        if(nll && !lemma_nll){
            lemma_nll = false;
            // std::cout << "lemma count = " << nll_lemma_count << "\n";
            for(ResolventAppSet::iterator it = nll->proofs.begin(), en = nll->proofs.end(); it != en; ++it){
                Z3_resolvent *res = *it;
                ast arg = res->proof;
                std::set<ast> loc_hyps; get_local_hyps(arg,loc_hyps); 
                if(!add_local_antes(arg,loc_hyps)){
                    local_antes.clear();  // clear antecedents for next lemma
                    antes_added.clear();
                    antes.clear();
                    return 0;
                }
            }
            collect_all_resolvent_lits(nll,lits);
        }
        int my_count = nll_lemma_count++;
        int res;
        try {
            res = extract_th_lemma_common(lits,nll,lemma_nll);
        }
#if 1
        catch (const invalid_lemma &) {
            std::cout << "\n\nlemma: " << my_count;
            std::cout << "\n\nproof node: \n";
            show_step(proof);
            std::cout << "\n\nnon-local: \n";
            show_nll(nll);
            pfgoto(nll->proofs[0]->proof);
            show(conc(pfhist.back()));
            pfprem(1);
            show(conc(pfhist.back()));
            pfprem(0);
            show(conc(pfhist.back()));
            pfprem(0);
            show(conc(pfhist.back()));
            pfprem(0);
            show(conc(pfhist.back()));
            std::cout << "\n\nliterals: \n";
            for(int i = 0; i < lits.size(); i++)
                show_lit(lits[i]);
            throw invalid_lemma();
        }
#endif
    
        return res;
#else
#ifdef SIMPLE_PROOFS
        if(local_antes_simple && !nll)
            return extract_th_lemma_simple(proof, lits);
#endif
        return extract_th_lemma_common(lits,nll);
#endif
    }

    int extract_th_lemma_ur(ast proof, int position, std::vector<ast> &lits, non_local_lits *nll){
        for(int i = 0; i <= position; i++){
            ast arg = prem(proof,i);
            if(!add_local_antes(arg,get_hyps(proof),i==0)){
                local_antes.clear();  // clear antecedents for next lemma
                antes_added.clear();
                antes.clear();
                return 0;
            }
        }
        return extract_th_lemma_common(lits,nll);
    }

    // see if any of the pushed resolvents are resolutions
    // push the current proof into the latest such
    int push_into_resolvent(ast proof, std::vector<ast> &lits, non_local_lits *nll, bool expect_clause){
        if(!nll) return 0;
        if(num_args(proof) > 1) return 0;
        ResolventAppSet resos = nll->proofs;
        int pos = resos.size()-1;
        for( ResolventAppSet::reverse_iterator it = resos.rbegin(), en = resos.rend(); it != en; ++it, --pos){
            Z3_resolvent *reso = *it;
            ast ante = reso->proof;
            ast pivot = reso->pivot;
            bool is_unit = reso->is_unit;
            pfrule dk = pr(ante);
            bool pushable = dk == PR_UNIT_RESOLUTION || dk == PR_LEMMA;
            if(!pushable && num_args(ante) > 1){
#if 0
                if (!is_local(conc(ante)))
                    std::cout << "non-local ";
                std::cout << "pushable!\n";
#endif
                pushable = true;
            }
            if(pushable){
                // remove the resolvent from list and add new clause as resolvent
                resos.erase((++it).base());
                for(; pos < (int)resos.size(); pos++){
                    Z3_resolvent *r = resos[pos];
                    resos[pos] = find_resolvent(r->proof,r->is_unit,mk_not(pivot));
                }
                resos.push_back(find_resolvent(proof,!expect_clause,mk_not(pivot)));
                non_local_lits *new_nll = find_nll(resos);
                try {
                    int res = translate_main(ante,new_nll,!is_unit);
                    return res;
                }
                catch (const invalid_lemma &) {
                    std::cout << "\n\npushing: \n";
                    std::cout << "nproof node: \n";
                    show_step(proof);
                    std::cout << "\n\nold non-local: \n";
                    show_nll(nll);
                    std::cout << "\n\nnew non-local: \n";
                    show_nll(new_nll);
                    throw invalid_lemma();
                }
            }
        }
        return 0; // no pushed resolvents are resolution steps
    }

    non_local_lits *find_nll(ResolventAppSet &proofs){
        if(proofs.empty())
            return (non_local_lits *)nullptr;
        std::pair<non_local_lits,non_local_lits *> foo(non_local_lits(proofs),(non_local_lits *)nullptr);
        std::pair<hash_map<non_local_lits, non_local_lits *>::iterator,bool> bar = 
            non_local_lits_unique.insert(foo);
        non_local_lits *&res = bar.first->second;
        if(bar.second)
            res = new non_local_lits(bar.first->first);
        return res;
    }

    Z3_resolvent *find_resolvent(ast proof, bool unit, ast pivot){
        std::pair<Z3_resolvent,Z3_resolvent *> foo(Z3_resolvent(proof,unit,pivot),(Z3_resolvent *)nullptr);
        std::pair<hash_map<Z3_resolvent, Z3_resolvent *>::iterator,bool> bar = 
            Z3_resolvent_unique.insert(foo);
        Z3_resolvent *&res = bar.first->second;
        if(bar.second)
            res = new Z3_resolvent(bar.first->first);
        return res;
    }

    // translate a unit resolution at position pos of given app
    int translate_ur(ast proof, int position, non_local_lits *nll){
        ast ante =  prem(proof,position);
        if(position <= 0)
            return translate_main(ante, nll);
        ast pnode = conc(ante);
        ast pnode_abs = !is_not(pnode) ? pnode : mk_not(pnode);
        if(is_local(pnode) ||  equivs.find(pnode) != equivs.end()){
            Iproof::node neg = translate_ur(proof,position-1,nll);
            Iproof::node pos = translate_main(ante, nll, false);
            if(is_not(pnode)){
                pnode = mk_not(pnode);
                std::swap(neg,pos);
            }
            try {
                return iproof->make_resolution(pnode,neg,pos);
            }
            catch (const iz3proof::proof_error &){
                std::cout << "resolution error in unit_resolution, position" << position << "\n";
                show_step(proof);
                throw invalid_lemma();
            }
        }
        else {
            // non-local pivot we have no local equivalent for
            if(true){
                // try pushing the non-local resolution up
                pfrule dk = pr(ante);
                non_local_lits *old_nll = nll;
                if(dk == PR_HYPOTHESIS)
                    ; //std::cout << "non-local hyp!\n";  // resolving with a hyp is a no-op 
                else {
                    ResolventAppSet new_proofs;
                    if(nll) new_proofs = nll->proofs;
                    Z3_resolvent *reso = find_resolvent(ante,true,pnode);
                    new_proofs.push_back(reso);
                    nll = find_nll(new_proofs);
                }
                try {
                    return translate_ur(proof,position-1,nll);
                }
                catch (const invalid_lemma &) {
                    if(old_nll != nll){
                        std::cout << "\n\nadded_nll: \n";
                        std::cout << "nproof node: \n";
                        show_step(proof);
                        std::cout << "\n\new non-local step: \n";
                        show_step(nll->proofs.back()->proof);
                    }
                    throw invalid_lemma();
                }

            }
            else {
                // just make a lemma
                std::vector<ast> lits;
                do_unit_resolution(proof,position,lits);
                int res;
                if(!(res = extract_th_lemma_ur(proof,position,lits,nll))){
                    for(int i = 0; i <= position; i++){
                        z3pf p = prem(proof,i);
                        add_antes(p);
                    }
                    res = fix_lemma(lits,get_hyps(proof),nll);
                }
                return res;
            }
        }
    }

    non_local_lits *update_nll(ast proof, bool expect_clause, non_local_lits *nll){
        std::vector<ast> lits;
        collect_proof_clause(proof,expect_clause,lits);
        AstSet litset;
        litset.insert(lits.begin(),lits.end());
        ResolventAppSet to_keep;
        for(int i = nll->proofs.size()-1; i >= 0; --i){
            ast traced_lit = (nll->proofs[i])->pivot;
            ast traced_lit_neg = mk_not(traced_lit);
            if(litset.find(traced_lit) != litset.end() || litset.find(traced_lit_neg) != litset.end()){
                to_keep.push_back(nll->proofs[i]);
                std::vector<ast> reslits;
                AstSet dummy;
                collect_resolvent_lits(nll->proofs[i],dummy,reslits);
                litset.insert(reslits.begin(),reslits.end());
            }    
        }
        if(to_keep.size() == nll->proofs.size()) return nll;
        ResolventAppSet new_proofs;
        for(int i = to_keep.size() - 1; i >= 0; --i)
            new_proofs.push_back(to_keep[i]);
        return find_nll(new_proofs);
    }

    // translate a Z3 proof term into a secondary prover proof term

    Iproof::node translate_main(ast proof, non_local_lits *nll, bool expect_clause = true){
        non_local_lits *old_nll = nll;
        if(nll) nll = update_nll(proof,expect_clause,nll);
        AstToIpf &tr = nll ? non_local_translation[nll] : translation; 
        hash_map<ast,Iproof::node> &trc = expect_clause ? tr.first : tr.second;
        std::pair<ast,int> foo(proof,INT_MAX);
        std::pair<AstToInt::iterator, bool> bar = trc.insert(foo);
        int &res = bar.first->second;
        if(!bar.second) return res;


        try {
            int frame = get_locality(proof);
            if(frame != -1){
                ast e = from_ast(conc(proof));
                if(frame >= frames) frame = frames - 1;
                std::vector<ast> foo;
                if(expect_clause)
                    get_Z3_lits(conc(proof),foo);
                else
                    foo.push_back(e);
                AstSet &hyps = get_hyps(proof);
                for(AstSet::iterator it = hyps.begin(), en = hyps.end(); it != en; ++it)
                    foo.push_back(mk_not(*it));
                res = iproof->make_assumption(frame,foo);
                return res;
            }

            pfrule dk = pr(proof);
            unsigned nprems = num_prems(proof);
            if(dk == PR_UNIT_RESOLUTION){
                res = translate_ur(proof, nprems - 1, nll);
            }
            else if(dk == PR_LEMMA){
                ast contra = prem(proof,0); // this is a proof of false from some hyps
                res = translate_main(contra, nll);
                if(!expect_clause){
                    std::vector<ast> foo;  // the negations of the hyps form a clause
                    foo.push_back(from_ast(conc(proof)));
                    AstSet &hyps = get_hyps(proof);
                    for(AstSet::iterator it = hyps.begin(), en = hyps.end(); it != en; ++it)
                        foo.push_back(mk_not(*it));
                    res = iproof->make_contra(res,foo);
                }
            }
            else {
                std::vector<ast> lits;
                ast con = conc(proof);
                if(expect_clause)
                    get_Z3_lits(con, lits);
                else
                    lits.push_back(from_ast(con));
#ifdef NEW_EXTRACT_TH_LEMMA
                if(!(res = push_into_resolvent(proof,lits,nll,expect_clause))){
                    if(!(res = extract_th_lemma(proof,lits,nll))){
#else
                        if(!(res = extract_th_lemma(proof,lits,nll))){
                            if(!(res = push_into_resolvent(proof,lits,nll,expect_clause))){
#endif
                                // std::cout << "extract theory lemma failed\n";
                                add_antes(proof);
                                res = fix_lemma(lits,get_hyps(proof),nll);
                            }
                        }
                    }
#ifdef CHECK_PROOFS

                    if(0){
                        AstSet zpf_con_lits, ipf_con_lits;
                        get_local_conclusion_lits(proof, expect_clause, zpf_con_lits);
                        if(nll){
                            for(unsigned i = 0; i < nll->proofs.size(); i++)
                                get_local_conclusion_lits(nll->proofs[i]->proof,!nll->proofs[i]->is_unit,zpf_con_lits);
                        }
                        std::vector<ast> ipf_con;
                        iproof->get_conclusion(res,ipf_con);
                        for(unsigned i = 0; i < ipf_con.size(); i++)
                            ipf_con_lits.insert(ipf_con[i]);
                        if(!(ipf_con_lits == zpf_con_lits)){
                            std::cout << "proof error:\n";
                            std::cout << "expected lits:\n";
                            for(AstSet::iterator hit = zpf_con_lits.begin(), hen = zpf_con_lits.end(); hit != hen; ++hit)
                                show_lit(*hit);
                            std::cout << "got lits:\n";
                            for(AstSet::iterator hit = ipf_con_lits.begin(), hen = ipf_con_lits.end(); hit != hen; ++hit)
                                show_lit(*hit);
                            std::cout << "\nproof step:";
                            show_step(proof);
                            std::cout << "\n";
                            throw invalid_lemma();
                        }
                    }
#endif

                    return res;
                }

                catch (const invalid_lemma &) {
                    if(old_nll != nll){
                        std::cout << "\n\nupdated nll: \n";
                        std::cout << "nproof node: \n";
                        show_step(proof);
                        std::cout << "\n\new non-local: \n";
                        show_nll(nll);
                    }
                    throw invalid_lemma();
                }

            }

            // Proof translation is in two stages:
            // 1) Translate ast proof term to Zproof
            // 2) Translate Zproof to Iproof

            Iproof::node translate(ast proof, Iproof &dst) override {
                iproof = &dst;
                Iproof::node Ipf = translate_main(proof,nullptr);  // builds result in dst
                return Ipf;
            }

            iz3translation_direct(iz3mgr &mgr,
                                  iz3secondary *_secondary,
                                  const std::vector<std::vector<ast> > &cnsts,
                                  const std::vector<int> &parents,
                                  const std::vector<ast> &theory)
                : iz3translation(mgr, cnsts, parents, theory)
                {
                    secondary = _secondary;
                    frames = cnsts.size();
                    traced_lit = ast();
                }

            ~iz3translation_direct() override {
                for(hash_map<non_local_lits, non_local_lits *>::iterator
                        it = non_local_lits_unique.begin(),
                        en = non_local_lits_unique.end();
                    it != en;
                    ++it)
                    delete it->second;

                for(hash_map<Z3_resolvent, Z3_resolvent *>::iterator
                        it = Z3_resolvent_unique.begin(),
                        en = Z3_resolvent_unique.end();
                    it != en;
                    ++it)
                    delete it->second;
            }
        };




#ifdef IZ3_TRANSLATE_DIRECT

        iz3translation *iz3translation::create(iz3mgr &mgr,
                                               iz3secondary *secondary,
                                               const std::vector<std::vector<ast> > &cnsts,
                                               const std::vector<int> &parents,
                                               const std::vector<ast> &theory){
            return new iz3translation_direct(mgr,secondary,cnsts,parents,theory);
        }


#if 1

        void iz3translation_direct_trace_lit(iz3translation_direct *p, iz3mgr::ast lit, iz3mgr::ast proof){
            p->trace_lit(lit, proof);
        }

        void iz3translation_direct_show_step(iz3translation_direct *p,  iz3mgr::ast proof){
            p->show_step(proof);
        }

        void iz3translation_direct_show_marked(iz3translation_direct *p,  iz3mgr::ast proof){
            p->show_marked(proof);
        }

        void iz3translation_direct_show_lit(iz3translation_direct *p,  iz3mgr::ast lit){
            p->show_lit(lit);
        }

        void iz3translation_direct_show_z3_lit(iz3translation_direct *p, iz3mgr::ast a){
            p->show_z3_lit(a);
        }

        void iz3translation_direct_pfgoto(iz3translation_direct *p, iz3mgr::ast proof){
            p->pfgoto(proof);
        }
  
        void iz3translation_direct_show_nll(iz3translation_direct *p, non_local_lits *nll){
            p->show_nll(nll);
        }

        void iz3translation_direct_pfback(iz3translation_direct *p ){
            p->pfback();
        }

        void iz3translation_direct_pffwd(iz3translation_direct *p ){
            p->pffwd();
        }

        void iz3translation_direct_pfprem(iz3translation_direct *p, int i){
            p->pfprem(i);
        }


        struct stdio_fixer {
            stdio_fixer(){
                std::cout.rdbuf()->pubsetbuf(0,0);
            }

        } my_stdio_fixer;

#endif

#endif