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GCC Code Coverage Report
Directory:	.		Exec	Total	Coverage
File:	src/theory/quantifiers/fmf/full_model_check.cpp	Lines:	763	802	95.1 %
Date:	2021-09-07	Branches:	1665	3243	51.3 %

/******************************************************************************
 * Top contributors (to current version):
 *   Andrew Reynolds, Mathias Preiner, Aina Niemetz
 *
 * This file is part of the cvc5 project.
 *
 * Copyright (c) 2009-2021 by the authors listed in the file AUTHORS
 * in the top-level source directory and their institutional affiliations.
 * All rights reserved.  See the file COPYING in the top-level source
 * directory for licensing information.
 * ****************************************************************************
 *
 * Implementation of full model check class.
 */

#include "theory/quantifiers/fmf/full_model_check.h"

#include "expr/skolem_manager.h"
#include "options/quantifiers_options.h"
#include "options/strings_options.h"
#include "options/theory_options.h"
#include "options/uf_options.h"
#include "theory/quantifiers/first_order_model.h"
#include "theory/quantifiers/fmf/bounded_integers.h"
#include "theory/quantifiers/instantiate.h"
#include "theory/quantifiers/quant_rep_bound_ext.h"
#include "theory/quantifiers/quantifiers_inference_manager.h"
#include "theory/quantifiers/quantifiers_registry.h"
#include "theory/quantifiers/quantifiers_state.h"
#include "theory/quantifiers/term_database.h"
#include "theory/quantifiers/term_util.h"
#include "theory/rewriter.h"

using namespace cvc5::kind;
using namespace cvc5::context;

namespace cvc5 {
namespace theory {
namespace quantifiers {
namespace fmcheck {

struct ModelBasisArgSort
{
  std::vector< Node > d_terms;
  // number of arguments that are model-basis terms
  std::unordered_map<Node, unsigned> d_mba_count;
  bool operator() (int i,int j) {
    return (d_mba_count[d_terms[i]] < d_mba_count[d_terms[j]]);
  }
};

bool EntryTrie::hasGeneralization( FirstOrderModelFmc * m, Node c, int index ) {
  if (index==(int)c.getNumChildren()) {
    return d_data!=-1;
  }else{
    TypeNode tn = c[index].getType();
    Node st = m->getStar(tn);
    if(d_child.find(st)!=d_child.end()) {
      if( d_child[st].hasGeneralization(m, c, index+1) ){
        return true;
      }
    }
    if( c[index]!=st && d_child.find( c[index] )!=d_child.end() ){
      if( d_child[ c[index] ].hasGeneralization(m, c, index+1) ){
        return true;
      }
    }
    if( c[index].getType().isSort() ){
      //for star: check if all children are defined and have generalizations
      if( c[index]==st ){     ///options::fmfFmcCoverSimplify()
        //check if all children exist and are complete
        unsigned num_child_def =
            d_child.size() - (d_child.find(st) != d_child.end() ? 1 : 0);
        if (num_child_def == m->getRepSet()->getNumRepresentatives(tn))
        {
          bool complete = true;
          for ( std::map<Node,EntryTrie>::iterator it = d_child.begin(); it != d_child.end(); ++it ){
            if( !m->isStar(it->first) ){
              if( !it->second.hasGeneralization(m, c, index+1) ){
                complete = false;
                break;
              }
            }
          }
          if( complete ){
            return true;
          }
        }
      }
    }

    return false;
  }
}

int EntryTrie::getGeneralizationIndex( FirstOrderModelFmc * m, std::vector<Node> & inst, int index ) {
  Debug("fmc-entry-trie") << "Get generalization index " << inst.size() << " " << index << std::endl;
  if (index==(int)inst.size()) {
    return d_data;
  }else{
    int minIndex = -1;
    Node st = m->getStar(inst[index].getType());
    if (d_child.find(st) != d_child.end())
    {
      minIndex = d_child[st].getGeneralizationIndex(m, inst, index + 1);
    }
    Node cc = inst[index];
    if (cc != st && d_child.find(cc) != d_child.end())
    {
      int gindex = d_child[cc].getGeneralizationIndex(m, inst, index + 1);
      if (minIndex == -1 || (gindex != -1 && gindex < minIndex))
      {
        minIndex = gindex;
      }
    }
    return minIndex;
  }
}

void EntryTrie::addEntry( FirstOrderModelFmc * m, Node c, Node v, int data, int index ) {
  if (index==(int)c.getNumChildren()) {
    if(d_data==-1) {
      d_data = data;
    }
  }
  else {
    d_child[ c[index] ].addEntry(m,c,v,data,index+1);
    if( d_complete==0 ){
      d_complete = -1;
    }
  }
}

void EntryTrie::getEntries( FirstOrderModelFmc * m, Node c, std::vector<int> & compat, std::vector<int> & gen, int index, bool is_gen ) {
  if (index==(int)c.getNumChildren()) {
    if( d_data!=-1) {
      if( is_gen ){
        gen.push_back(d_data);
      }
      compat.push_back(d_data);
    }
  }else{
    if (m->isStar(c[index])) {
      for ( std::map<Node,EntryTrie>::iterator it = d_child.begin(); it != d_child.end(); ++it ){
        it->second.getEntries(m, c, compat, gen, index+1, is_gen );
      }
    }else{
      Node st = m->getStar(c[index].getType());
      if(d_child.find(st)!=d_child.end()) {
        d_child[st].getEntries(m, c, compat, gen, index+1, false);
      }
      if( d_child.find( c[index] )!=d_child.end() ){
        d_child[ c[index] ].getEntries(m, c, compat, gen, index+1, is_gen);
      }
    }

  }
}

bool Def::addEntry( FirstOrderModelFmc * m, Node c, Node v) {
  if (d_et.hasGeneralization(m, c)) {
    Trace("fmc-debug") << "Already has generalization, skip." << std::endl;
    return false;
  }
  int newIndex = (int)d_cond.size();
  if (!d_has_simplified) {
    std::vector<int> compat;
    std::vector<int> gen;
    d_et.getEntries(m, c, compat, gen);
    for( unsigned i=0; i<compat.size(); i++) {
      if( d_status[compat[i]]==status_unk ){
        if( d_value[compat[i]]!=v ){
          d_status[compat[i]] = status_non_redundant;
        }
      }
    }
    for( unsigned i=0; i<gen.size(); i++) {
      if( d_status[gen[i]]==status_unk ){
        if( d_value[gen[i]]==v ){
          d_status[gen[i]] = status_redundant;
        }
      }
    }
    d_status.push_back( status_unk );
  }
  d_et.addEntry(m, c, v, newIndex);
  d_cond.push_back(c);
  d_value.push_back(v);
  return true;
}

Node Def::evaluate( FirstOrderModelFmc * m, std::vector<Node>& inst ) {
  int gindex = d_et.getGeneralizationIndex(m, inst);
  if (gindex!=-1) {
    return d_value[gindex];
  }else{
    Trace("fmc-warn") << "Warning : evaluation came up null!" << std::endl;
    return Node::null();
  }
}

int Def::getGeneralizationIndex( FirstOrderModelFmc * m, std::vector<Node>& inst ) {
  return d_et.getGeneralizationIndex(m, inst);
}

void Def::basic_simplify( FirstOrderModelFmc * m ) {
  d_has_simplified = true;
  std::vector< Node > cond;
  cond.insert( cond.end(), d_cond.begin(), d_cond.end() );
  d_cond.clear();
  std::vector< Node > value;
  value.insert( value.end(), d_value.begin(), d_value.end() );
  d_value.clear();
  d_et.reset();
  for (unsigned i=0; i<d_status.size(); i++) {
    if( d_status[i]!=status_redundant ){
      addEntry(m, cond[i], value[i]);
    }
  }
  d_status.clear();
}

void Def::simplify(FullModelChecker * mc, FirstOrderModelFmc * m) {
  Trace("fmc-simplify") << "Simplify definition, #cond = " << d_cond.size() << std::endl;
  basic_simplify( m );
  Trace("fmc-simplify") << "post-basic simplify, #cond = " << d_cond.size() << std::endl;

  //check if the last entry is not all star, if so, we can make the last entry all stars
  if( !d_cond.empty() ){
    bool last_all_stars = true;
    Node cc = d_cond[d_cond.size()-1];
    for( unsigned i=0; i<cc.getNumChildren(); i++ ){
      if (!m->isStar(cc[i]))
      {
        last_all_stars = false;
        break;
      }
    }
    if( !last_all_stars ){
      Trace("fmc-cover-simplify") << "Need to modify last entry to be all stars." << std::endl;
      Trace("fmc-cover-simplify") << "Before: " << std::endl;
      debugPrint("fmc-cover-simplify",Node::null(), mc);
      Trace("fmc-cover-simplify") << std::endl;
      std::vector< Node > cond;
      cond.insert( cond.end(), d_cond.begin(), d_cond.end() );
      d_cond.clear();
      std::vector< Node > value;
      value.insert( value.end(), d_value.begin(), d_value.end() );
      d_value.clear();
      d_et.reset();
      d_has_simplified = false;
      //change the last to all star
      std::vector< Node > nc;
      nc.push_back( cc.getOperator() );
      for( unsigned j=0; j< cc.getNumChildren(); j++){
        nc.push_back(m->getStar(cc[j].getType()));
      }
      cond[cond.size()-1] = NodeManager::currentNM()->mkNode( APPLY_UF, nc );
      //re-add the entries
      for (unsigned i=0; i<cond.size(); i++) {
        addEntry(m, cond[i], value[i]);
      }
      Trace("fmc-cover-simplify") << "Finished re-adding entries." << std::endl;
      basic_simplify( m );
      Trace("fmc-cover-simplify") << "After: " << std::endl;
      debugPrint("fmc-cover-simplify",Node::null(), mc);
      Trace("fmc-cover-simplify") << std::endl;
    }
  }
  Trace("fmc-simplify") << "finish simplify, #cond = " << d_cond.size() << std::endl;
}

void Def::debugPrint(const char * tr, Node op, FullModelChecker * m) {
  if (!op.isNull()) {
    Trace(tr) << "Model for " << op << " : " << std::endl;
  }
  for( unsigned i=0; i<d_cond.size(); i++) {
    //print the condition
    if (!op.isNull()) {
      Trace(tr) << op;
    }
    m->debugPrintCond(tr, d_cond[i], true);
    Trace(tr) << " -> ";
    m->debugPrint(tr, d_value[i]);
    Trace(tr) << std::endl;
  }
}

FullModelChecker::FullModelChecker(QuantifiersState& qs,
                                   QuantifiersInferenceManager& qim,
                                   QuantifiersRegistry& qr,
                                   TermRegistry& tr)
    : QModelBuilder(qs, qim, qr, tr), d_fm(new FirstOrderModelFmc(qs, qr, tr))
{
  d_true = NodeManager::currentNM()->mkConst(true);
  d_false = NodeManager::currentNM()->mkConst(false);
}

void FullModelChecker::finishInit() { d_model = d_fm.get(); }

bool FullModelChecker::preProcessBuildModel(TheoryModel* m) {
  //standard pre-process
  if( !preProcessBuildModelStd( m ) ){
    return false;
  }

  Trace("fmc") << "---Full Model Check preprocess() " << std::endl;
  d_preinitialized_eqc.clear();
  d_preinitialized_types.clear();
  //traverse equality engine
  eq::EqClassesIterator eqcs_i = eq::EqClassesIterator(m->getEqualityEngine());
  while( !eqcs_i.isFinished() ){
    Node r = *eqcs_i;
    TypeNode tr = r.getType();
    d_preinitialized_eqc[tr] = r;
    ++eqcs_i;
  }

  //must ensure model basis terms exists in model for each relevant type
  Trace("fmc") << "preInitialize types..." << std::endl;
  d_fm->initialize();
  for (std::pair<const Node, Def*>& mp : d_fm->d_models)
  {
    Node op = mp.first;
    Trace("fmc") << "preInitialize types for " << op << std::endl;
    TypeNode tno = op.getType();
    for( unsigned i=0; i<tno.getNumChildren(); i++) {
      Trace("fmc") << "preInitializeType " << tno[i] << std::endl;
      preInitializeType(m, tno[i]);
      Trace("fmc") << "finished preInitializeType " << tno[i] << std::endl;
    }
  }
  Trace("fmc") << "Finish preInitialize types" << std::endl;
  //do not have to introduce terms for sorts of domains of quantified formulas if we are allowed to assume empty sorts
  for (unsigned i = 0, nquant = d_fm->getNumAssertedQuantifiers(); i < nquant;
       i++)
  {
    Node q = d_fm->getAssertedQuantifier(i);
    registerQuantifiedFormula(q);
    if (!isHandled(q))
    {
      continue;
    }
    // make sure all types are set
    for (const Node& v : q[0])
    {
      preInitializeType(m, v.getType());
    }
  }
  return true;
}

bool FullModelChecker::processBuildModel(TheoryModel* m){
  if (!m->areFunctionValuesEnabled())
  {
    // nothing to do if no functions
    return true;
  }
  FirstOrderModelFmc* fm = d_fm.get();
  Trace("fmc") << "---Full Model Check reset() " << std::endl;
  d_quant_models.clear();
  d_rep_ids.clear();
  d_star_insts.clear();
  //process representatives
  RepSet* rs = m->getRepSetPtr();
  for (std::map<TypeNode, std::vector<Node> >::iterator it =
           rs->d_type_reps.begin();
       it != rs->d_type_reps.end();
       ++it)
  {
    if( it->first.isSort() ){
      Trace("fmc") << "Cardinality( " << it->first << " )" << " = " << it->second.size() << std::endl;
      for( size_t a=0; a<it->second.size(); a++ ){
        Node r = m->getRepresentative(it->second[a]);
        if( Trace.isOn("fmc-model-debug") ){
          std::vector< Node > eqc;
          d_qstate.getEquivalenceClass(r, eqc);
          Trace("fmc-model-debug") << "   " << (it->second[a]==r);
          Trace("fmc-model-debug") << " : " << it->second[a] << " : " << r << " : ";
          //Trace("fmc-model-debug") << r2 << " : " << ir << " : ";
          Trace("fmc-model-debug") << " {";
          for( size_t i=0; i<eqc.size(); i++ ){
            Trace("fmc-model-debug") << eqc[i] << ", ";
          }
          Trace("fmc-model-debug") << "}" << std::endl;
        }
        d_rep_ids[it->first][r] = (int)a;
      }
      Trace("fmc-model-debug") << std::endl;
    }
  }

  //now, make models
  for (std::pair<const Node, Def*>& fmm : d_fm->d_models)
  {
    Node op = fmm.first;
    //reset the model
    d_fm->d_models[op]->reset();

    std::vector< Node > add_conds;
    std::vector< Node > add_values;
    bool needsDefault = true;
    if (m->hasUfTerms(op))
    {
      const std::vector<Node>& uft = m->getUfTerms(op);
      Trace("fmc-model-debug")
          << uft.size() << " model values for " << op << " ... " << std::endl;
      for (const Node& n : uft)
      {
        // only consider unique up to congruence (in model equality engine)?
        add_conds.push_back( n );
        add_values.push_back( n );
        Node r = m->getRepresentative(n);
        Trace("fmc-model-debug") << n << " -> " << r << std::endl;
      }
    }else{
      Trace("fmc-model-debug") << "No model values for " << op << " ... " << std::endl;
    }
    Trace("fmc-model-debug") << std::endl;
    //possibly get default
    if( needsDefault ){
      Node nmb = d_fm->getModelBasisOpTerm(op);
      //add default value if necessary
      if (m->hasTerm(nmb))
      {
        Trace("fmc-model-debug") << "Add default " << nmb << std::endl;
        add_conds.push_back( nmb );
        add_values.push_back( nmb );
      }else{
        Node vmb = getSomeDomainElement(d_fm.get(), nmb.getType());
        Trace("fmc-model-debug") << "Add default to default representative " << nmb << " ";
        Trace("fmc-model-debug")
            << m->getRepSet()->getNumRepresentatives(nmb.getType())
            << std::endl;
        add_conds.push_back( nmb );
        add_values.push_back( vmb );
      }
    }

    std::vector< Node > conds;
    std::vector< Node > values;
    std::vector< Node > entry_conds;
    //get the entries for the model
    for( size_t i=0; i<add_conds.size(); i++ ){
      Node c = add_conds[i];
      Node v = add_values[i];
      Trace("fmc-model-debug")
          << "Add cond/value : " << c << " -> " << v << std::endl;
      std::vector< Node > children;
      std::vector< Node > entry_children;
      children.push_back(op);
      entry_children.push_back(op);
      bool hasNonStar = false;
      for (const Node& ci : c)
      {
        Node ri = fm->getRepresentative(ci);
        children.push_back(ri);
        bool isStar = false;
        if (fm->isModelBasisTerm(ri))
        {
          ri = fm->getStar(ri.getType());
          isStar = true;
        }
        else
        {
          hasNonStar = true;
        }
        if( !isStar && !ri.isConst() ){
          Trace("fmc-warn") << "Warning : model for " << op
                            << " has non-constant argument in model " << ri
                            << " (from " << ci << ")" << std::endl;
          Assert(false);
        }
        entry_children.push_back(ri);
      }
      Node n = NodeManager::currentNM()->mkNode( APPLY_UF, children );
      Node nv = fm->getRepresentative( v );
      Trace("fmc-model-debug")
          << "Representative of " << v << " is " << nv << std::endl;
      if( !nv.isConst() ){
        Trace("fmc-warn") << "Warning : model for " << op << " has non-constant value in model " << nv << std::endl;
        Assert(false);
      }
      Node en = (useSimpleModels() && hasNonStar) ? n : NodeManager::currentNM()->mkNode( APPLY_UF, entry_children );
      if( std::find(conds.begin(), conds.end(), n )==conds.end() ){
        Trace("fmc-model-debug") << "- add " << n << " -> " << nv << " (entry is " << en << ")" << std::endl;
        conds.push_back(n);
        values.push_back(nv);
        entry_conds.push_back(en);
      }
      else {
        Trace("fmc-model-debug") << "Already have entry for : " << n << " -> " << nv << " (entry is " << en << ")" << std::endl;
      }
    }


    //sort based on # default arguments
    std::vector< int > indices;
    ModelBasisArgSort mbas;
    for (int i=0; i<(int)conds.size(); i++) {
      mbas.d_terms.push_back(conds[i]);
      mbas.d_mba_count[conds[i]] = fm->getModelBasisArg(conds[i]);
      indices.push_back(i);
    }
    std::sort( indices.begin(), indices.end(), mbas );

    for (int i=0; i<(int)indices.size(); i++) {
      fm->d_models[op]->addEntry(fm, entry_conds[indices[i]], values[indices[i]]);
    }

    Trace("fmc-model-simplify") << "Before simplification : " << std::endl;
    fm->d_models[op]->debugPrint("fmc-model-simplify", op, this);
    Trace("fmc-model-simplify") << std::endl;

    Trace("fmc-model-simplify") << "Simplifying " << op << "..." << std::endl;
    fm->d_models[op]->simplify( this, fm );

    fm->d_models[op]->debugPrint("fmc-model", op, this);
    Trace("fmc-model") << std::endl;

    //for debugging
    /*
    for( size_t i=0; i<fm->d_uf_terms[op].size(); i++ ){
      std::vector< Node > inst;
      for( unsigned j=0; j<fm->d_uf_terms[op][i].getNumChildren(); j++ ){
        Node r = fm->getRepresentative( fm->d_uf_terms[op][i][j] );
        inst.push_back( r );
      }
      Node ev = fm->d_models[op]->evaluate( fm, inst );
      Trace("fmc-model-debug") << ".....Checking eval( " <<
    fm->d_uf_terms[op][i] << " ) = " << ev << std::endl; AlwaysAssert(
    fm->areEqual( ev, fm->d_uf_terms[op][i] ) );
    }
    */
  }
  Assert(d_addedLemmas == 0);

  //make function values
  for( std::map<Node, Def * >::iterator it = fm->d_models.begin(); it != fm->d_models.end(); ++it ){
    Node f_def = getFunctionValue( fm, it->first, "$x" );
    m->assignFunctionDefinition( it->first, f_def );
  }
  return TheoryEngineModelBuilder::processBuildModel( m );
}

void FullModelChecker::preInitializeType(TheoryModel* m, TypeNode tn)
{
  if( d_preinitialized_types.find( tn )==d_preinitialized_types.end() ){
    d_preinitialized_types[tn] = true;
    if (tn.isFirstClass())
    {
      Trace("fmc") << "Get model basis term " << tn << "..." << std::endl;
      Node mb = d_fm->getModelBasisTerm(tn);
      Trace("fmc") << "...return " << mb << std::endl;
      // if the model basis term does not exist in the model,
      // either add it directly to the model's equality engine if no other terms
      // of this type exist, or otherwise assert that it is equal to the first
      // equivalence class of its type.
      if (!m->hasTerm(mb) && !mb.isConst())
      {
        std::map<TypeNode, Node>::iterator itpe = d_preinitialized_eqc.find(tn);
        if (itpe == d_preinitialized_eqc.end())
        {
          Trace("fmc") << "...add model basis term to EE of model " << mb << " "
                       << tn << std::endl;
          m->getEqualityEngine()->addTerm(mb);
        }
        else
        {
          Trace("fmc") << "...add model basis eqc equality to model " << mb
                       << " == " << itpe->second << " " << tn << std::endl;
          bool ret = m->assertEquality(mb, itpe->second, true);
          AlwaysAssert(ret);
        }
      }
    }
  }
}

void FullModelChecker::debugPrintCond(const char * tr, Node n, bool dispStar) {
  Trace(tr) << "(";
  for( unsigned j=0; j<n.getNumChildren(); j++) {
    if( j>0 ) Trace(tr) << ", ";
    debugPrint(tr, n[j], dispStar);
  }
  Trace(tr) << ")";
}

void FullModelChecker::debugPrint(const char * tr, Node n, bool dispStar) {
  if( n.isNull() ){
    Trace(tr) << "null";
  }
  else if (FirstOrderModelFmc::isStar(n) && dispStar)
  {
    Trace(tr) << "*";
  }
  else
  {
    TypeNode tn = n.getType();
    if( tn.isSort() && d_rep_ids.find(tn)!=d_rep_ids.end() ){
      if (d_rep_ids[tn].find(n)!=d_rep_ids[tn].end()) {
        Trace(tr) << d_rep_ids[tn][n];
      }else{
        Trace(tr) << n;
      }
    }else{
      Trace(tr) << n;
    }
  }
}


int FullModelChecker::doExhaustiveInstantiation( FirstOrderModel * fm, Node f, int effort ) {
  Trace("fmc") << "Full model check " << f << ", effort = " << effort << "..." << std::endl;
  // register the quantifier
  registerQuantifiedFormula(f);
  Assert(!d_qstate.isInConflict());
  // we do not do model-based quantifier instantiation if the option
  // disables it, or if the quantified formula has an unhandled type.
  if (!optUseModel() || !isHandled(f))
  {
    return 0;
  }
  FirstOrderModelFmc* fmfmc = static_cast<FirstOrderModelFmc*>(fm);
  if (effort == 0)
  {
    if (options::mbqiMode() == options::MbqiMode::NONE)
    {
      // just exhaustive instantiate
      Node c = mkCondDefault(fmfmc, f);
      d_quant_models[f].addEntry(fmfmc, c, d_false);
      if (!exhaustiveInstantiate(fmfmc, f, c))
      {
        return 0;
      }
      return 1;
    }
    // model check the quantifier
    doCheck(fmfmc, f, d_quant_models[f], f[1]);
    std::vector<Node>& mcond = d_quant_models[f].d_cond;
    Trace("fmc") << "Definition for quantifier " << f << " is : " << std::endl;
    Assert(!mcond.empty());
    d_quant_models[f].debugPrint("fmc", Node::null(), this);
    Trace("fmc") << std::endl;

    // consider all entries going to non-true
    Instantiate* instq = d_qim.getInstantiate();
    for (unsigned i = 0, msize = mcond.size(); i < msize; i++)
    {
      if (d_quant_models[f].d_value[i] == d_true)
      {
        // already satisfied
        continue;
      }
      Trace("fmc-inst") << "Instantiate based on " << mcond[i] << "..."
                        << std::endl;
      bool hasStar = false;
      std::vector<Node> inst;
      for (unsigned j = 0, nchild = mcond[i].getNumChildren(); j < nchild; j++)
      {
        if (fmfmc->isStar(mcond[i][j]))
        {
          hasStar = true;
          inst.push_back(fmfmc->getModelBasisTerm(mcond[i][j].getType()));
        }
        else
        {
          inst.push_back(mcond[i][j]);
        }
      }
      bool addInst = true;
      if (hasStar)
      {
        // try obvious (specified by inst)
        Node ev = d_quant_models[f].evaluate(fmfmc, inst);
        if (ev == d_true)
        {
          addInst = false;
          Trace("fmc-debug")
              << "...do not instantiate, evaluation was " << ev << std::endl;
        }
      }
      else
      {
        // for debugging
        if (Trace.isOn("fmc-test-inst"))
        {
          Node ev = d_quant_models[f].evaluate(fmfmc, inst);
          if (ev == d_true)
          {
            CVC5Message() << "WARNING: instantiation was true! " << f << " "
                          << mcond[i] << std::endl;
            AlwaysAssert(false);
          }
          else
          {
            Trace("fmc-test-inst")
                << "...instantiation evaluated to false." << std::endl;
          }
        }
      }
      if (!addInst)
      {
        Trace("fmc-debug-inst")
            << "** Instantiation was already true." << std::endl;
        // might try it next effort level
        d_star_insts[f].push_back(i);
        continue;
      }
      if (options::fmfBound() || options::stringExp())
      {
        std::vector<Node> cond;
        cond.push_back(d_quant_cond[f]);
        cond.insert(cond.end(), inst.begin(), inst.end());
        // need to do exhaustive instantiate algorithm to set things properly
        // (should only add one instance)
        Node c = mkCond(cond);
        unsigned prevInst = d_addedLemmas;
        exhaustiveInstantiate(fmfmc, f, c);
        if (d_addedLemmas == prevInst)
        {
          d_star_insts[f].push_back(i);
        }
        continue;
      }
      // just add the instance
      d_triedLemmas++;
      if (instq->addInstantiation(f,
                                  inst,
                                  InferenceId::QUANTIFIERS_INST_FMF_FMC,
                                  Node::null(),
                                  true))
      {
        Trace("fmc-debug-inst") << "** Added instantiation." << std::endl;
        d_addedLemmas++;
        if (d_qstate.isInConflict() || options::fmfOneInstPerRound())
        {
          break;
        }
      }
      else
      {
        Trace("fmc-debug-inst")
            << "** Instantiation was duplicate." << std::endl;
        // might try it next effort level
        d_star_insts[f].push_back(i);
      }
    }
    return 1;
  }
  // Get the list of instantiation regions (described by "star entries" in the
  // definition) that were not tried at the previous effort level. For each
  // of these, we add one instantiation.
  std::vector<Node>& mcond = d_quant_models[f].d_cond;
  if (!d_star_insts[f].empty())
  {
    if (Trace.isOn("fmc-exh"))
    {
      Trace("fmc-exh") << "Exhaustive instantiate " << f << std::endl;
      Trace("fmc-exh") << "Definition was : " << std::endl;
      d_quant_models[f].debugPrint("fmc-exh", Node::null(), this);
      Trace("fmc-exh") << std::endl;
    }
    Def temp;
    // simplify the exceptions?
    for (int i = (d_star_insts[f].size() - 1); i >= 0; i--)
    {
      // get witness for d_star_insts[f][i]
      int j = d_star_insts[f][i];
      if (temp.addEntry(fmfmc, mcond[j], d_quant_models[f].d_value[j]))
      {
        if (!exhaustiveInstantiate(fmfmc, f, mcond[j]))
        {
          // something went wrong, resort to exhaustive instantiation
          return 0;
        }
      }
    }
  }
  return 1;
}

/** Representative bound fmc entry
 *
 * This bound information corresponds to one
 * entry in a term definition (see terminology in
 * Chapter 5 of Finite Model Finding for
 * Satisfiability Modulo Theories thesis).
 * For example, a term definition for the body
 * of a quantified formula:
 *   forall xyz. P( x, y, z )
 * may be:
 *   ( 0, 0, 0 ) -> false
 *   ( *, 1, 2 ) -> false
 *   ( *, *, * ) -> true
 * Indicating that the quantified formula evaluates
 * to false in the current model for x=0, y=0, z=0,
 * or y=1, z=2 for any x, and evaluates to true
 * otherwise.
 * This class is used if we wish
 * to iterate over all values corresponding to one
 * of these entries. For example, for the second entry:
 *   (*, 1, 2 )
 * we iterate over all values of x, but only {1}
 * for y and {2} for z.
 */
class RepBoundFmcEntry : public QRepBoundExt
{
 public:
  RepBoundFmcEntry(QuantifiersBoundInference& qbi,
                   Node e,
                   FirstOrderModelFmc* f)
      : QRepBoundExt(qbi, f), d_entry(e), d_fm(f)
  {
  }
  ~RepBoundFmcEntry() {}
  /** set bound */
  virtual RsiEnumType setBound(Node owner,
                               unsigned i,
                               std::vector<Node>& elements) override
  {
    if (!d_fm->isStar(d_entry[i]))
    {
      // only need to consider the single point
      elements.push_back(d_entry[i]);
      return ENUM_DEFAULT;
    }
    return QRepBoundExt::setBound(owner, i, elements);
  }

 private:
  /** the entry for this bound */
  Node d_entry;
  /** the model builder associated with this bound */
  FirstOrderModelFmc* d_fm;
};

bool FullModelChecker::exhaustiveInstantiate(FirstOrderModelFmc* fm,
                                             Node f,
                                             Node c)
{
  Trace("fmc-exh") << "----Exhaustive instantiate based on " << c << " ";
  debugPrintCond("fmc-exh", c, true);
  Trace("fmc-exh")<< std::endl;
  QuantifiersBoundInference& qbi = d_qreg.getQuantifiersBoundInference();
  RepBoundFmcEntry rbfe(qbi, c, fm);
  RepSetIterator riter(fm->getRepSet(), &rbfe);
  Trace("fmc-exh-debug") << "Set quantifier..." << std::endl;
  //initialize
  if (riter.setQuantifier(f))
  {
    Trace("fmc-exh-debug") << "Set element domains..." << std::endl;
    int addedLemmas = 0;
    //now do full iteration
    Instantiate* ie = d_qim.getInstantiate();
    while( !riter.isFinished() ){
      d_triedLemmas++;
      Trace("fmc-exh-debug") << "Inst : ";
      std::vector< Node > ev_inst;
      std::vector< Node > inst;
      for (unsigned i = 0; i < riter.getNumTerms(); i++)
      {
        TypeNode tn = riter.getTypeOf(i);
        // if the type is not closed enumerable (see
        // TypeNode::isClosedEnumerable), then we must ensure that we are
        // using a term and not a value. This ensures that e.g. uninterpreted
        // constants do not appear in instantiations.
        Node rr = riter.getCurrentTerm(i, !tn.isClosedEnumerable());
        Node r = fm->getRepresentative(rr);
        debugPrint("fmc-exh-debug", r);
        Trace("fmc-exh-debug") << " (term : " << rr << ")";
        ev_inst.push_back( r );
        inst.push_back( rr );
      }
      int ev_index = d_quant_models[f].getGeneralizationIndex(fm, ev_inst);
      Trace("fmc-exh-debug") << ", index = " << ev_index << " / " << d_quant_models[f].d_value.size();
      Node ev = ev_index==-1 ? Node::null() : d_quant_models[f].d_value[ev_index];
      if (ev!=d_true) {
        Trace("fmc-exh-debug") << ", add!";
        //add as instantiation
        if (ie->addInstantiation(f,
                                 inst,
                                 InferenceId::QUANTIFIERS_INST_FMF_FMC_EXH,
                                 Node::null(),
                                 true))
        {
          Trace("fmc-exh-debug")  << " ...success.";
          addedLemmas++;
          if (d_qstate.isInConflict() || options::fmfOneInstPerRound())
          {
            break;
          }
        }else{
          Trace("fmc-exh-debug") << ", failed.";
        }
      }else{
        Trace("fmc-exh-debug") << ", already true";
      }
      Trace("fmc-exh-debug") << std::endl;
      int index = riter.increment();
      Trace("fmc-exh-debug") << "Incremented index " << index << std::endl;
      if( !riter.isFinished() ){
        if (index >= 0 && riter.d_index[index] > 0 && addedLemmas > 0
            && riter.d_enum_type[index] == ENUM_CUSTOM)
        {
          Trace("fmc-exh-debug")
              << "Since this is a custom enumeration, skip to the next..."
              << std::endl;
          riter.incrementAtIndex(index - 1);
        }
      }
    }
    d_addedLemmas += addedLemmas;
    Trace("fmc-exh") << "----Finished Exhaustive instantiate, lemmas = " << addedLemmas << ", incomplete=" << riter.isIncomplete() << std::endl;
    return addedLemmas>0 || !riter.isIncomplete();
  }else{
    Trace("fmc-exh") << "----Finished Exhaustive instantiate, failed." << std::endl;
    return !riter.isIncomplete();
  }
}

void FullModelChecker::doCheck(FirstOrderModelFmc * fm, Node f, Def & d, Node n ) {
  Trace("fmc-debug") << "Check " << n << " " << n.getKind() << std::endl;
  //first check if it is a bounding literal
  if( n.hasAttribute(BoundIntLitAttribute()) ){
    Trace("fmc-debug") << "It is a bounding literal, polarity = " << n.getAttribute(BoundIntLitAttribute()) << std::endl;
    d.addEntry(fm, mkCondDefault(fm, f), n.getAttribute(BoundIntLitAttribute())==1 ? d_false : d_true );
  }else if( n.getKind() == kind::BOUND_VARIABLE ){
    Trace("fmc-debug") << "Add default entry..." << std::endl;
    d.addEntry(fm, mkCondDefault(fm, f), n);
  }
  else if( n.getKind() == kind::NOT ){
    //just do directly
    doCheck( fm, f, d, n[0] );
    doNegate( d );
  }
  else if( n.getKind() == kind::FORALL ){
    d.addEntry(fm, mkCondDefault(fm, f), Node::null());
  }
  else if( n.getType().isArray() ){
    //Trace("fmc-warn") << "WARNING : ARRAYS : Can't process base array " << r << std::endl;
    //Trace("fmc-warn") << "          Default value was : " << odefaultValue << std::endl;
    //Trace("fmc-debug") << "Can't process base array " << r << std::endl;
    //can't process this array
    d.reset();
    d.addEntry(fm, mkCondDefault(fm, f), Node::null());
  }
  else if( n.getNumChildren()==0 ){
    Node r = n;
    if( !n.isConst() ){
      TypeNode tn = n.getType();
      if( !fm->hasTerm(n) && tn.isFirstClass() ){
        r = getSomeDomainElement(fm, tn );
      }
      r = fm->getRepresentative( r );
    }
    Trace("fmc-debug") << "Add constant entry..." << std::endl;
    d.addEntry(fm, mkCondDefault(fm, f), r);
  }
  else{
    std::vector< int > var_ch;
    std::vector< Def > children;
    for( int i=0; i<(int)n.getNumChildren(); i++) {
      Def dc;
      doCheck(fm, f, dc, n[i]);
      children.push_back(dc);
      if( n[i].getKind() == kind::BOUND_VARIABLE ){
        var_ch.push_back(i);
      }
    }

    if( n.getKind()==APPLY_UF ){
      Trace("fmc-debug") << "Do uninterpreted compose " << n << std::endl;
      //uninterpreted compose
      doUninterpretedCompose( fm, f, d, n.getOperator(), children );
      /*
    } else if( n.getKind()==SELECT ){
      Trace("fmc-debug") << "Do select compose " << n << std::endl;
      std::vector< Def > children2;
      children2.push_back( children[1] );
      std::vector< Node > cond;
      mkCondDefaultVec(fm, f, cond);
      std::vector< Node > val;
      doUninterpretedCompose(fm, f, d, children[0], children2, 0, cond, val );
      */
    } else {
      if( !var_ch.empty() ){
        if( n.getKind()==EQUAL && !n[0].getType().isBoolean() ){
          if( var_ch.size()==2 ){
            Trace("fmc-debug") << "Do variable equality " << n << std::endl;
            doVariableEquality( fm, f, d, n );
          }else{
            Trace("fmc-debug") << "Do variable relation " << n << std::endl;
            doVariableRelation( fm, f, d, var_ch[0]==0 ? children[1] : children[0], var_ch[0]==0 ? n[0] : n[1] );
          }
        }else{
          Trace("fmc-warn") << "Don't know how to check " << n << std::endl;
          d.addEntry(fm, mkCondDefault(fm, f), Node::null());
        }
      }else{
        Trace("fmc-debug") << "Do interpreted compose " << n << std::endl;
        std::vector< Node > cond;
        mkCondDefaultVec(fm, f, cond);
        std::vector< Node > val;
        //interpreted compose
        doInterpretedCompose( fm, f, d, n, children, 0, cond, val );
      }
    }
    Trace("fmc-debug") << "Simplify the definition..." << std::endl;
    d.debugPrint("fmc-debug", Node::null(), this);
    d.simplify(this, fm);
    Trace("fmc-debug") << "Done simplifying" << std::endl;
  }
  Trace("fmc-debug") << "Definition for " << n << " is : " << std::endl;
  d.debugPrint("fmc-debug", Node::null(), this);
  Trace("fmc-debug") << std::endl;
}

void FullModelChecker::doNegate( Def & dc ) {
  for (unsigned i=0; i<dc.d_cond.size(); i++) {
    Node v = dc.d_value[i];
    if (!v.isNull())
    {
      // In the case that the value is not-constant, we cannot reason about
      // its value (since the range of this must be a constant or variable).
      // In particular, returning null here is important if we have (not x)
      // where x is a bound variable.
      dc.d_value[i] =
          v == d_true ? d_false : (v == d_false ? d_true : Node::null());
    }
  }
}

void FullModelChecker::doVariableEquality( FirstOrderModelFmc * fm, Node f, Def & d, Node eq ) {
  std::vector<Node> cond;
  mkCondDefaultVec(fm, f, cond);
  if (eq[0]==eq[1]){
    d.addEntry(fm, mkCond(cond), d_true);
  }else{
    TypeNode tn = eq[0].getType();
    if( tn.isSort() ){
      int j = fm->getVariableId(f, eq[0]);
      int k = fm->getVariableId(f, eq[1]);
      const RepSet* rs = fm->getRepSet();
      if (!rs->hasType(tn))
      {
        getSomeDomainElement( fm, tn );  //to verify the type is initialized
      }
      unsigned nreps = rs->getNumRepresentatives(tn);
      for (unsigned i = 0; i < nreps; i++)
      {
        Node r = fm->getRepresentative(rs->getRepresentative(tn, i));
        cond[j+1] = r;
        cond[k+1] = r;
        d.addEntry( fm, mkCond(cond), d_true);
      }
      d.addEntry( fm, mkCondDefault(fm, f), d_false);
    }else{
      d.addEntry( fm, mkCondDefault(fm, f), Node::null());
    }
  }
}

void FullModelChecker::doVariableRelation( FirstOrderModelFmc * fm, Node f, Def & d, Def & dc, Node v) {
  int j = fm->getVariableId(f, v);
  for (unsigned i=0; i<dc.d_cond.size(); i++) {
    Node val = dc.d_value[i];
    if( val.isNull() ){
      d.addEntry( fm, dc.d_cond[i], val);
    }else{
      if( dc.d_cond[i][j]!=val ){
        if (fm->isStar(dc.d_cond[i][j])) {
          std::vector<Node> cond;
          mkCondVec(dc.d_cond[i],cond);
          cond[j+1] = val;
          d.addEntry(fm, mkCond(cond), d_true);
          cond[j+1] = fm->getStar(val.getType());
          d.addEntry(fm, mkCond(cond), d_false);
        }else{
          d.addEntry( fm, dc.d_cond[i], d_false);
        }
      }else{
        d.addEntry( fm, dc.d_cond[i], d_true);
      }
    }
  }
}

void FullModelChecker::doUninterpretedCompose( FirstOrderModelFmc * fm, Node f, Def & d, Node op, std::vector< Def > & dc ) {
  Trace("fmc-uf-debug") << "Definition : " << std::endl;
  fm->d_models[op]->debugPrint("fmc-uf-debug", op, this);
  Trace("fmc-uf-debug") << std::endl;

  std::vector< Node > cond;
  mkCondDefaultVec(fm, f, cond);
  std::vector< Node > val;
  doUninterpretedCompose( fm, f, d, *fm->d_models[op], dc, 0, cond, val);
}

void FullModelChecker::doUninterpretedCompose( FirstOrderModelFmc * fm, Node f, Def & d,
                                               Def & df, std::vector< Def > & dc, int index,
                                               std::vector< Node > & cond, std::vector<Node> & val ) {
  Trace("fmc-uf-process") << "process at " << index << std::endl;
  for( unsigned i=1; i<cond.size(); i++) {
    debugPrint("fmc-uf-process", cond[i], true);
    Trace("fmc-uf-process") << " ";
  }
  Trace("fmc-uf-process") << std::endl;
  if (index==(int)dc.size()) {
    //we have an entry, now do actual compose
    std::map< int, Node > entries;
    doUninterpretedCompose2( fm, f, entries, 0, cond, val, df.d_et);
    if( entries.empty() ){
      d.addEntry(fm, mkCond(cond), Node::null());
    }else{
      //add them to the definition
      for( unsigned e=0; e<df.d_cond.size(); e++ ){
        if ( entries.find(e)!=entries.end() ){
          Trace("fmf-uf-process-debug") << "Add entry..." << std::endl;
          d.addEntry(fm, entries[e], df.d_value[e] );
          Trace("fmf-uf-process-debug") << "Done add entry." << std::endl;
        }
      }
    }
  }else{
    for (unsigned i=0; i<dc[index].d_cond.size(); i++) {
      if (isCompat(fm, cond, dc[index].d_cond[i])!=0) {
        std::vector< Node > new_cond;
        new_cond.insert(new_cond.end(), cond.begin(), cond.end());
        if( doMeet(fm, new_cond, dc[index].d_cond[i]) ){
          Trace("fmc-uf-process") << "index " << i << " succeeded meet." << std::endl;
          val.push_back(dc[index].d_value[i]);
          doUninterpretedCompose(fm, f, d, df, dc, index+1, new_cond, val);
          val.pop_back();
        }else{
          Trace("fmc-uf-process") << "index " << i << " failed meet." << std::endl;
        }
      }
    }
  }
}

void FullModelChecker::doUninterpretedCompose2( FirstOrderModelFmc * fm, Node f,
                                                std::map< int, Node > & entries, int index,
                                                std::vector< Node > & cond, std::vector< Node > & val,
                                                EntryTrie & curr ) {
  Trace("fmc-uf-process") << "compose " << index << " / " << val.size() << std::endl;
  for( unsigned i=1; i<cond.size(); i++) {
    debugPrint("fmc-uf-process", cond[i], true);
    Trace("fmc-uf-process") << " ";
  }
  Trace("fmc-uf-process") << std::endl;
  if (index==(int)val.size()) {
    Node c = mkCond(cond);
    Trace("fmc-uf-entry") << "Entry : " << c << " -> index[" << curr.d_data << "]" << std::endl;
    entries[curr.d_data] = c;
  }else{
    Node v = val[index];
    Trace("fmc-uf-process") << "Process " << v << std::endl;
    bool bind_var = false;
    if( !v.isNull() && v.getKind()==kind::BOUND_VARIABLE ){
      int j = fm->getVariableId(f, v);
      Trace("fmc-uf-process") << v << " is variable #" << j << std::endl;
      if (!fm->isStar(cond[j + 1]))
      {
        v = cond[j+1];
      }else{
        bind_var = true;
      }
    }
    if (bind_var) {
      Trace("fmc-uf-process") << "bind variable..." << std::endl;
      int j = fm->getVariableId(f, v);
      Assert(fm->isStar(cond[j + 1]));
      for (std::map<Node, EntryTrie>::iterator it = curr.d_child.begin();
           it != curr.d_child.end();
           ++it)
      {
        cond[j + 1] = it->first;
        doUninterpretedCompose2(
            fm, f, entries, index + 1, cond, val, it->second);
      }
      cond[j + 1] = fm->getStar(v.getType());
    }else{
      if( !v.isNull() ){
        if (curr.d_child.find(v) != curr.d_child.end())
        {
          Trace("fmc-uf-process") << "follow value..." << std::endl;
          doUninterpretedCompose2(
              fm, f, entries, index + 1, cond, val, curr.d_child[v]);
        }
        Node st = fm->getStar(v.getType());
        if (curr.d_child.find(st) != curr.d_child.end())
        {
          Trace("fmc-uf-process") << "follow star..." << std::endl;
          doUninterpretedCompose2(
              fm, f, entries, index + 1, cond, val, curr.d_child[st]);
        }
      }
    }
  }
}

void FullModelChecker::doInterpretedCompose( FirstOrderModelFmc * fm, Node f, Def & d, Node n,
                                             std::vector< Def > & dc, int index,
                                             std::vector< Node > & cond, std::vector<Node> & val ) {
  Trace("fmc-if-process") << "int compose " << index << " / " << dc.size() << std::endl;
  for( unsigned i=1; i<cond.size(); i++) {
    debugPrint("fmc-if-process", cond[i], true);
    Trace("fmc-if-process") << " ";
  }
  Trace("fmc-if-process") << std::endl;
  if ( index==(int)dc.size() ){
    Node c = mkCond(cond);
    Node v = evaluateInterpreted(n, val);
    d.addEntry(fm, c, v);
  }
  else {
    TypeNode vtn = n.getType();
    for (unsigned i=0; i<dc[index].d_cond.size(); i++) {
      if (isCompat(fm, cond, dc[index].d_cond[i])!=0) {
        std::vector< Node > new_cond;
        new_cond.insert(new_cond.end(), cond.begin(), cond.end());
        if( doMeet(fm, new_cond, dc[index].d_cond[i]) ){
          bool process = true;
          if (vtn.isBoolean()) {
            //short circuit
            if( (n.getKind()==OR && dc[index].d_value[i]==d_true) ||
                (n.getKind()==AND && dc[index].d_value[i]==d_false) ){
              Node c = mkCond(new_cond);
              d.addEntry(fm, c, dc[index].d_value[i]);
              process = false;
            }
          }
          if (process) {
            val.push_back(dc[index].d_value[i]);
            doInterpretedCompose(fm, f, d, n, dc, index+1, new_cond, val);
            val.pop_back();
          }
        }
      }
    }
  }
}

int FullModelChecker::isCompat( FirstOrderModelFmc * fm, std::vector< Node > & cond, Node c ) {
  Trace("fmc-debug3") << "isCompat " << c << std::endl;
  Assert(cond.size() == c.getNumChildren() + 1);
  for (unsigned i=1; i<cond.size(); i++) {
    if (cond[i] != c[i - 1] && !fm->isStar(cond[i]) && !fm->isStar(c[i - 1]))
    {
      return 0;
    }
  }
  return 1;
}

bool FullModelChecker::doMeet( FirstOrderModelFmc * fm, std::vector< Node > & cond, Node c ) {
  Trace("fmc-debug3") << "doMeet " << c << std::endl;
  Assert(cond.size() == c.getNumChildren() + 1);
  for (unsigned i=1; i<cond.size(); i++) {
    if( cond[i]!=c[i-1] ) {
      if (fm->isStar(cond[i]))
      {
        cond[i] = c[i - 1];
      }
      else if (!fm->isStar(c[i - 1]))
      {
        return false;
      }
    }
  }
  return true;
}

Node FullModelChecker::mkCond( std::vector< Node > & cond ) {
  return NodeManager::currentNM()->mkNode(APPLY_UF, cond);
}

Node FullModelChecker::mkCondDefault( FirstOrderModelFmc * fm, Node f) {
  std::vector< Node > cond;
  mkCondDefaultVec(fm, f, cond);
  return mkCond(cond);
}

void FullModelChecker::mkCondDefaultVec( FirstOrderModelFmc * fm, Node f, std::vector< Node > & cond ) {
  Trace("fmc-debug") << "Make default vec" << std::endl;
  //get function symbol for f
  cond.push_back(d_quant_cond[f]);
  for (unsigned i=0; i<f[0].getNumChildren(); i++) {
    Node ts = fm->getStar(f[0][i].getType());
    Assert(ts.getType() == f[0][i].getType());
    cond.push_back(ts);
  }
}

void FullModelChecker::mkCondVec( Node n, std::vector< Node > & cond ) {
  cond.push_back(n.getOperator());
  for( unsigned i=0; i<n.getNumChildren(); i++ ){
    cond.push_back( n[i] );
  }
}

Node FullModelChecker::evaluateInterpreted( Node n, std::vector< Node > & vals ) {
  if( n.getKind()==EQUAL && !n[0].getType().isBoolean() ){
    if (!vals[0].isNull() && !vals[1].isNull()) {
      return vals[0]==vals[1] ? d_true : d_false;
    }else{
      return Node::null();
    }
  }else if( n.getKind()==ITE ){
    if( vals[0]==d_true ){
      return vals[1];
    }else if( vals[0]==d_false ){
      return vals[2];
    }else{
      return vals[1]==vals[2] ? vals[1] : Node::null();
    }
  }else if( n.getKind()==AND || n.getKind()==OR ){
    bool isNull = false;
    for (unsigned i=0; i<vals.size(); i++) {
      if((vals[i]==d_true && n.getKind()==OR) || (vals[i]==d_false && n.getKind()==AND)) {
        return vals[i];
      }else if( vals[i].isNull() ){
        isNull = true;
      }
    }
    return isNull ? Node::null() : vals[0];
  }else{
    std::vector<Node> children;
    if( n.getMetaKind() == kind::metakind::PARAMETERIZED ){
      children.push_back( n.getOperator() );
    }
    for (unsigned i=0; i<vals.size(); i++) {
      if( vals[i].isNull() ){
        return Node::null();
      }else{
        children.push_back( vals[i] );
      }
    }
    Node nc = NodeManager::currentNM()->mkNode(n.getKind(), children);
    Trace("fmc-eval") << "Evaluate " << nc << " to ";
    nc = Rewriter::rewrite(nc);
    Trace("fmc-eval") << nc << std::endl;
    return nc;
  }
}

Node FullModelChecker::getSomeDomainElement( FirstOrderModelFmc * fm, TypeNode tn ) {
  bool addRepId = !fm->getRepSet()->hasType(tn);
  Node de = fm->getSomeDomainElement(tn);
  if( addRepId ){
    d_rep_ids[tn][de] = 0;
  }
  return de;
}

Node FullModelChecker::getFunctionValue(FirstOrderModelFmc * fm, Node op, const char* argPrefix ) {
  return fm->getFunctionValue(op, argPrefix);
}


bool FullModelChecker::useSimpleModels() {
  return options::fmfFmcSimple();
}
void FullModelChecker::registerQuantifiedFormula(Node q)
{
  if (d_quant_cond.find(q) != d_quant_cond.end())
  {
    return;
  }
  NodeManager* nm = NodeManager::currentNM();
  SkolemManager* sm = nm->getSkolemManager();
  std::vector<TypeNode> types;
  for (const Node& v : q[0])
  {
    TypeNode tn = v.getType();
    if (tn.isFunction())
    {
      // we will not use model-based quantifier instantiation for q, since
      // the model-based instantiation algorithm does not handle (universally
      // quantified) functions
      d_unhandledQuant.insert(q);
    }
    types.push_back(tn);
  }
  TypeNode typ = nm->mkFunctionType(types, nm->booleanType());
  Node op = sm->mkDummySkolem("qfmc", typ, "op for full-model checking");
  d_quant_cond[q] = op;
}

bool FullModelChecker::isHandled(Node q) const
{
  return d_unhandledQuant.find(q) == d_unhandledQuant.end();
}

}  // namespace fmcheck
}  // namespace quantifiers
}  // namespace theory
}  // namespace cvc5

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