/*********************                                                        */
/*! \file term_database_sygus.cpp
 ** \verbatim
 ** Top contributors (to current version):
 **   Andrew Reynolds
 ** This file is part of the CVC4 project.
 ** Copyright (c) 2009-2017 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.\endverbatim
 **
 ** \brief Implementation of term database sygus class
 **/

#include "theory/quantifiers/term_database_sygus.h"

#include "options/quantifiers_options.h"
#include "theory/arith/arith_msum.h"
#include "theory/quantifiers/quantifiers_attributes.h"
#include "theory/quantifiers/term_database.h"
#include "theory/quantifiers/term_util.h"
#include "theory/quantifiers_engine.h"

using namespace std;
using namespace CVC4::kind;
using namespace CVC4::context;
using namespace CVC4::theory::inst;

namespace CVC4 {
namespace theory {
namespace quantifiers {

TermDbSygus::TermDbSygus(context::Context* c, QuantifiersEngine* qe)
    : d_quantEngine(qe),
      d_syexp(new SygusExplain(this)),
      d_ext_rw(new ExtendedRewriter(true))
{
  d_true = NodeManager::currentNM()->mkConst( true );
  d_false = NodeManager::currentNM()->mkConst( false );
}

bool TermDbSygus::reset( Theory::Effort e ) { 
  return true;  
}

TNode TermDbSygus::getFreeVar( TypeNode tn, int i, bool useSygusType ) {
  unsigned sindex = 0;
  TypeNode vtn = tn;
  if( useSygusType ){
    if( tn.isDatatype() ){
      const Datatype& dt = ((DatatypeType)(tn).toType()).getDatatype();
      if( !dt.getSygusType().isNull() ){
        vtn = TypeNode::fromType( dt.getSygusType() );
        sindex = 1;
      } 
    }
  }
  while( i>=(int)d_fv[sindex][tn].size() ){
    std::stringstream ss;
    if( tn.isDatatype() ){
      const Datatype& dt = ((DatatypeType)(tn).toType()).getDatatype();
      ss << "fv_" << dt.getName() << "_" << i;
    }else{
      ss << "fv_" << tn << "_" << i;
    }
    Assert( !vtn.isNull() );
    Node v = NodeManager::currentNM()->mkSkolem( ss.str(), vtn, "for sygus normal form testing" );
    d_fv_stype[v] = tn;
    d_fv_num[v] = i;
    d_fv[sindex][tn].push_back( v );
  }
  return d_fv[sindex][tn][i];
}

TNode TermDbSygus::getFreeVarInc( TypeNode tn, std::map< TypeNode, int >& var_count, bool useSygusType ) {
  std::map< TypeNode, int >::iterator it = var_count.find( tn );
  if( it==var_count.end() ){
    var_count[tn] = 1;
    return getFreeVar( tn, 0, useSygusType );
  }else{
    int index = it->second;
    var_count[tn]++;
    return getFreeVar( tn, index, useSygusType );
  }
}

bool TermDbSygus::hasFreeVar( Node n, std::map< Node, bool >& visited ){
  if( visited.find( n )==visited.end() ){
    visited[n] = true;
    if( isFreeVar( n ) ){
      return true;    
    }
    for( unsigned i=0; i<n.getNumChildren(); i++ ){
      if( hasFreeVar( n[i], visited ) ){
        return true;
      }
    }
  }
  return false;
}

bool TermDbSygus::hasFreeVar( Node n ) {
  std::map< Node, bool > visited;
  return hasFreeVar( n, visited );
}
  
TypeNode TermDbSygus::getSygusTypeForVar( Node v ) {
  Assert( d_fv_stype.find( v )!=d_fv_stype.end() );
  return d_fv_stype[v];
}

Node TermDbSygus::mkGeneric(const Datatype& dt,
                            unsigned c,
                            std::map<TypeNode, int>& var_count,
                            std::map<int, Node>& pre)
{
  Assert(c < dt.getNumConstructors());
  Assert( dt.isSygus() );
  Assert( !dt[c].getSygusOp().isNull() );
  std::vector< Node > children;
  Node op = Node::fromExpr( dt[c].getSygusOp() );
  if( op.getKind()!=BUILTIN ){
    children.push_back( op );
  }
  Trace("sygus-db-debug") << "mkGeneric " << dt.getName() << " " << op << " " << op.getKind() << "..." << std::endl;
  for (unsigned i = 0, nargs = dt[c].getNumArgs(); i < nargs; i++)
  {
    TypeNode tna = getArgType( dt[c], i );
    Node a;
    std::map< int, Node >::iterator it = pre.find( i );
    if( it!=pre.end() ){
      a = it->second;
    }else{
      a = getFreeVarInc( tna, var_count, true );
    }
    Trace("sygus-db-debug")
        << "  child " << i << " : " << a << " : " << a.getType() << std::endl;
    Assert( !a.isNull() );
    children.push_back( a );
  }
  Node ret;
  if( op.getKind()==BUILTIN ){
    Trace("sygus-db-debug") << "Make builtin node..." << std::endl;
    ret = NodeManager::currentNM()->mkNode( op, children );
  }else{
    Kind ok = getOperatorKind( op );
    Trace("sygus-db-debug") << "Operator kind is " << ok << std::endl;
    if( children.size()==1 && ok==kind::UNDEFINED_KIND ){
      ret = children[0];
    }else{
      ret = NodeManager::currentNM()->mkNode( ok, children );
    }
  }
  Trace("sygus-db-debug") << "...returning " << ret << std::endl;
  return ret;
}

Node TermDbSygus::mkGeneric(const Datatype& dt, int c, std::map<int, Node>& pre)
{
  std::map<TypeNode, int> var_count;
  return mkGeneric(dt, c, var_count, pre);
}

Node TermDbSygus::sygusToBuiltin( Node n, TypeNode tn ) {
  Assert( n.getType()==tn );
  Assert( tn.isDatatype() );
  std::map< Node, Node >::iterator it = d_sygus_to_builtin[tn].find( n );
  if( it==d_sygus_to_builtin[tn].end() ){
    Trace("sygus-db-debug") << "SygusToBuiltin : compute for " << n << ", type = " << tn << std::endl;
    const Datatype& dt = ((DatatypeType)(tn).toType()).getDatatype();
    if( n.getKind()==APPLY_CONSTRUCTOR ){
      unsigned i = Datatype::indexOf( n.getOperator().toExpr() );
      Assert( n.getNumChildren()==dt[i].getNumArgs() );
      std::map< TypeNode, int > var_count;
      std::map< int, Node > pre;
      for (unsigned j = 0, size = n.getNumChildren(); j < size; j++)
      {
        pre[j] = sygusToBuiltin( n[j], getArgType( dt[i], j ) );
      }
      Node ret = mkGeneric(dt, i, var_count, pre);
      Trace("sygus-db-debug") << "SygusToBuiltin : Generic is " << ret << std::endl;
      d_sygus_to_builtin[tn][n] = ret;
      return ret;
    }
    if (n.hasAttribute(SygusPrintProxyAttribute()))
    {
      // this variable was associated by an attribute to a builtin node
      return n.getAttribute(SygusPrintProxyAttribute());
    }
    Assert(isFreeVar(n));
    // map to builtin variable type
    int fv_num = getVarNum(n);
    Assert(!dt.getSygusType().isNull());
    TypeNode vtn = TypeNode::fromType(dt.getSygusType());
    Node ret = getFreeVar(vtn, fv_num);
    return ret;
  }else{
    return it->second;
  }
}

Node TermDbSygus::sygusSubstituted( TypeNode tn, Node n, std::vector< Node >& args ) {
  Assert( d_var_list[tn].size()==args.size() );
  return n.substitute( d_var_list[tn].begin(), d_var_list[tn].end(), args.begin(), args.end() );
}

unsigned TermDbSygus::getSygusTermSize( Node n ){
  if( n.getNumChildren()==0 ){
    return 0;
  }else{
    Assert(n.getKind() == APPLY_CONSTRUCTOR);
    unsigned sum = 0;
    for( unsigned i=0; i<n.getNumChildren(); i++ ){
      sum += getSygusTermSize( n[i] );
    }
    const Datatype& dt = Datatype::datatypeOf(n.getOperator().toExpr());
    int cindex = Datatype::indexOf(n.getOperator().toExpr());
    Assert(cindex >= 0 && cindex < (int)dt.getNumConstructors());
    unsigned weight = dt[cindex].getWeight();
    return weight + sum;
  }
}

class ReqTrie {
public:
  ReqTrie() : d_req_kind( UNDEFINED_KIND ){}
  std::map< unsigned, ReqTrie > d_children;
  Kind d_req_kind;
  TypeNode d_req_type;
  Node d_req_const;
  void print( const char * c, int indent = 0 ){
    if( d_req_kind!=UNDEFINED_KIND ){
      Trace(c) << d_req_kind << " ";
    }else if( !d_req_type.isNull() ){
      Trace(c) << d_req_type;
    }else if( !d_req_const.isNull() ){
      Trace(c) << d_req_const;
    }else{
      Trace(c) << "_";
    }
    Trace(c) << std::endl;
    for( std::map< unsigned, ReqTrie >::iterator it = d_children.begin(); it != d_children.end(); ++it ){
      for( int i=0; i<=indent; i++ ) { Trace(c) << "  "; }
      Trace(c) << it->first << " : ";
      it->second.print( c, indent+1 );
    }
  }
  bool satisfiedBy( quantifiers::TermDbSygus * tdb, TypeNode tn ){
    if( !d_req_const.isNull() ){
      if( !tdb->hasConst( tn, d_req_const ) ){
        return false;
      }
    }
    if( !d_req_type.isNull() ){
      if( tn!=d_req_type ){
        return false;
      }
    }
    if( d_req_kind!=UNDEFINED_KIND ){
      int c = tdb->getKindConsNum( tn, d_req_kind );
      if( c!=-1 ){
        bool ret = true;
        const Datatype& dt = ((DatatypeType)(tn).toType()).getDatatype();
        for( std::map< unsigned, ReqTrie >::iterator it = d_children.begin(); it != d_children.end(); ++it ){
          if( it->first<dt[c].getNumArgs() ){
            TypeNode tnc = tdb->getArgType( dt[c], it->first );
            if( !it->second.satisfiedBy( tdb, tnc ) ){
              ret = false;
              break;
            }
          }else{
            ret = false;
            break;
          }
        }
        if( !ret ){
          return false;
        }
        // TODO : commutative operators try both?
      }else{
        return false;
      }
    }
    return true;
  }
  bool empty() {
    return d_req_kind==UNDEFINED_KIND && d_req_const.isNull() && d_req_type.isNull();
  }
};

//this function gets all easy redundant cases, before consulting rewriters
bool TermDbSygus::considerArgKind( TypeNode tn, TypeNode tnp, Kind k, Kind pk, int arg ) {
  const Datatype& pdt = ((DatatypeType)(tnp).toType()).getDatatype();
  const Datatype& dt = ((DatatypeType)(tn).toType()).getDatatype();
  Assert( hasKind( tn, k ) );
  Assert( hasKind( tnp, pk ) );
  Trace("sygus-sb-debug") << "Consider sygus arg kind " << k << ", pk = " << pk << ", arg = " << arg << "?" << std::endl;
  int c = getKindConsNum( tn, k );
  int pc = getKindConsNum( tnp, pk );
  if( k==pk ){
    //check for associativity
    if( quantifiers::TermUtil::isAssoc( k ) ){
      //if the operator is associative, then a repeated occurrence should only occur in the leftmost argument position
      int firstArg = getFirstArgOccurrence( pdt[pc], tn );
      Assert( firstArg!=-1 );
      if( arg!=firstArg ){
        Trace("sygus-sb-simple") << "  sb-simple : do not consider " << k << " at child arg " << arg << " of " << k << " since it is associative, with first arg = " << firstArg << std::endl;
        return false;
      }else{
        return true;
      }
    }
  }
  //describes the shape of an alternate term to construct
  //  we check whether this term is in the sygus grammar below
  ReqTrie rt;
  Assert( rt.empty() );
  
  //construct rt by cases
  if( pk==NOT || pk==BITVECTOR_NOT || pk==UMINUS || pk==BITVECTOR_NEG ){
    //negation normal form
    if( pk==k ){
      rt.d_req_type = getArgType( dt[c], 0 );
    }else{
      Kind reqk = UNDEFINED_KIND;       //required kind for all children
      std::map< unsigned, Kind > reqkc; //required kind for some children
      if( pk==NOT ){
        if( k==AND ) {
          rt.d_req_kind = OR;reqk = NOT;
        }else if( k==OR ){
          rt.d_req_kind = AND;reqk = NOT;
        //AJR : eliminate this if we eliminate xor
        }else if( k==EQUAL ) {
          rt.d_req_kind = XOR;
        }else if( k==XOR ) {
          rt.d_req_kind = EQUAL;
        }else if( k==ITE ){
          rt.d_req_kind = ITE;reqkc[1] = NOT;reqkc[2] = NOT;
          rt.d_children[0].d_req_type = getArgType( dt[c], 0 );
        }else if( k==LEQ || k==GT ){
          //  (not (~ x y)) ----->  (~ (+ y 1) x)
          rt.d_req_kind = k;
          rt.d_children[0].d_req_kind = PLUS;
          rt.d_children[0].d_children[0].d_req_type = getArgType( dt[c], 1 );
          rt.d_children[0].d_children[1].d_req_const = NodeManager::currentNM()->mkConst( Rational( 1 ) );
          rt.d_children[1].d_req_type = getArgType( dt[c], 0 );
          //TODO: other possibilities?
        }else if( k==LT || k==GEQ ){
          //  (not (~ x y)) ----->  (~ y (+ x 1))
          rt.d_req_kind = k;
          rt.d_children[0].d_req_type = getArgType( dt[c], 1 );
          rt.d_children[1].d_req_kind = PLUS;
          rt.d_children[1].d_children[0].d_req_type = getArgType( dt[c], 0 );
          rt.d_children[1].d_children[1].d_req_const = NodeManager::currentNM()->mkConst( Rational( 1 ) );
        }
      }else if( pk==BITVECTOR_NOT ){
        if( k==BITVECTOR_AND ) {
          rt.d_req_kind = BITVECTOR_OR;reqk = BITVECTOR_NOT;
        }else if( k==BITVECTOR_OR ){
          rt.d_req_kind = BITVECTOR_AND;reqk = BITVECTOR_NOT;
        }else if( k==BITVECTOR_XNOR ) {
          rt.d_req_kind = BITVECTOR_XOR;
        }else if( k==BITVECTOR_XOR ) {
          rt.d_req_kind = BITVECTOR_XNOR;
        }
      }else if( pk==UMINUS ){
        if( k==PLUS ){
          rt.d_req_kind = PLUS;reqk = UMINUS;
        }
      }else if( pk==BITVECTOR_NEG ){
        if( k==PLUS ){
          rt.d_req_kind = PLUS;reqk = BITVECTOR_NEG;
        }
      }
      if( !rt.empty() && ( reqk!=UNDEFINED_KIND || !reqkc.empty() ) ){
        int pcr = getKindConsNum( tnp, rt.d_req_kind );
        if( pcr!=-1 ){
          Assert( pcr<(int)pdt.getNumConstructors() );
          //must have same number of arguments
          if( pdt[pcr].getNumArgs()==dt[c].getNumArgs() ){
            for( unsigned i=0; i<pdt[pcr].getNumArgs(); i++ ){
              Kind rk = reqk;
              if( reqk==UNDEFINED_KIND ){
                std::map< unsigned, Kind >::iterator itr = reqkc.find( i );
                if( itr!=reqkc.end() ){
                  rk = itr->second;
                }
              }
              if( rk!=UNDEFINED_KIND ){
                rt.d_children[i].d_req_kind = rk;
                rt.d_children[i].d_children[0].d_req_type = getArgType( dt[c], i );
              }
            }
          }
        }
      }
    }
  }else if( k==MINUS || k==BITVECTOR_SUB ){
    if( pk==EQUAL || 
        pk==MINUS || pk==BITVECTOR_SUB || 
        pk==LEQ || pk==LT || pk==GEQ || pk==GT ){
      int oarg = arg==0 ? 1 : 0;
      //  (~ x (- y z))  ---->  (~ (+ x z) y)
      //  (~ (- y z) x)  ---->  (~ y (+ x z))
      rt.d_req_kind = pk;
      rt.d_children[arg].d_req_type = getArgType( dt[c], 0 );
      rt.d_children[oarg].d_req_kind = k==MINUS ? PLUS : BITVECTOR_PLUS;
      rt.d_children[oarg].d_children[0].d_req_type = getArgType( pdt[pc], oarg );
      rt.d_children[oarg].d_children[1].d_req_type = getArgType( dt[c], 1 );
    }else if( pk==PLUS || pk==BITVECTOR_PLUS ){
      //  (+ x (- y z))  -----> (- (+ x y) z)
      //  (+ (- y z) x)  -----> (- (+ x y) z)
      rt.d_req_kind = pk==PLUS ? MINUS : BITVECTOR_SUB;
      int oarg = arg==0 ? 1 : 0;
      rt.d_children[0].d_req_kind = pk;
      rt.d_children[0].d_children[0].d_req_type = getArgType( pdt[pc], oarg );
      rt.d_children[0].d_children[1].d_req_type = getArgType( dt[c], 0 );
      rt.d_children[1].d_req_type = getArgType( dt[c], 1 );
      // TODO : this is subsumbed by solving for MINUS
    }
  }else if( k==ITE ){
    if( pk!=ITE ){
      //  (o X (ite y z w) X')  -----> (ite y (o X z X') (o X w X'))
      rt.d_req_kind = ITE;
      rt.d_children[0].d_req_type = getArgType( dt[c], 0 );
      unsigned n_args = pdt[pc].getNumArgs();
      for( unsigned r=1; r<=2; r++ ){
        rt.d_children[r].d_req_kind = pk;
        for( unsigned q=0; q<n_args; q++ ){
          if( (int)q==arg ){
            rt.d_children[r].d_children[q].d_req_type = getArgType( dt[c], r );
          }else{
            rt.d_children[r].d_children[q].d_req_type = getArgType( pdt[pc], q );
          }
        }
      }
      //TODO: this increases term size but is probably a good idea
    }
  }else if( k==NOT ){
    if( pk==ITE ){
      //  (ite (not y) z w)  -----> (ite y w z)
      rt.d_req_kind = ITE;
      rt.d_children[0].d_req_type = getArgType( dt[c], 0 );
      rt.d_children[1].d_req_type = getArgType( pdt[pc], 2 );
      rt.d_children[2].d_req_type = getArgType( pdt[pc], 1 );
    }
  }
  Trace("sygus-sb-debug") << "Consider sygus arg kind " << k << ", pk = " << pk << ", arg = " << arg << "?" << std::endl;
  if( !rt.empty() ){
    rt.print("sygus-sb-debug");
    //check if it meets the requirements
    if( rt.satisfiedBy( this, tnp ) ){
      Trace("sygus-sb-debug") << "...success!" << std::endl;
      Trace("sygus-sb-simple") << "  sb-simple : do not consider " << k << " as arg " << arg << " of " << pk << std::endl;
      //do not need to consider the kind in the search since there are ways to construct equivalent terms
      return false;
    }else{
      Trace("sygus-sb-debug") << "...failed." << std::endl;
    }
    Trace("sygus-sb-debug") << std::endl;
  }
  //must consider this kind in the search  
  return true;
}

bool TermDbSygus::considerConst( TypeNode tn, TypeNode tnp, Node c, Kind pk, int arg ) {
  const Datatype& pdt = ((DatatypeType)(tnp).toType()).getDatatype();
  // child grammar-independent
  if( !considerConst( pdt, tnp, c, pk, arg ) ){
    return false;
  }
  // TODO : this can probably be made child grammar independent
  int pc = getKindConsNum( tnp, pk );
  if( pdt[pc].getNumArgs()==2 ){
    Kind ok;
    int offset;
    if (d_quantEngine->getTermUtil()->hasOffsetArg(pk, arg, offset, ok))
    {
      Trace("sygus-sb-simple-debug") << pk << " has offset arg " << ok << " " << offset << std::endl;
      int ok_arg = getKindConsNum( tnp, ok );
      if( ok_arg!=-1 ){
        Trace("sygus-sb-simple-debug") << "...at argument " << ok_arg << std::endl;
        //other operator be the same type
        if( isTypeMatch( pdt[ok_arg], pdt[arg] ) ){
          int status;
          Node co = d_quantEngine->getTermUtil()->getTypeValueOffset(
              c.getType(), c, offset, status);
          Trace("sygus-sb-simple-debug") << c << " with offset " << offset << " is " << co << ", status=" << status << std::endl;
          if( status==0 && !co.isNull() ){
            if( hasConst( tn, co ) ){
              Trace("sygus-sb-simple") << "  sb-simple : by offset reasoning, do not consider const " << c;
              Trace("sygus-sb-simple") << " as arg " << arg << " of " << pk << " since we can use " << co << " under " << ok << " " << std::endl;
              return false;
            }
          }
        }
      }
    }
  }
  return true;
}

bool TermDbSygus::considerConst( const Datatype& pdt, TypeNode tnp, Node c, Kind pk, int arg ) {
  Assert( hasKind( tnp, pk ) );
  int pc = getKindConsNum( tnp, pk );
  bool ret = true;
  Trace("sygus-sb-debug") << "Consider sygus const " << c << ", parent = " << pk << ", arg = " << arg << "?" << std::endl;
  if (d_quantEngine->getTermUtil()->isIdempotentArg(c, pk, arg))
  {
    if( pdt[pc].getNumArgs()==2 ){
      int oarg = arg==0 ? 1 : 0;
      TypeNode otn = TypeNode::fromType( ((SelectorType)pdt[pc][oarg].getType()).getRangeType() );
      if( otn==tnp ){
        Trace("sygus-sb-simple") << "  sb-simple : " << c << " is idempotent arg " << arg << " of " << pk << "..." << std::endl;
        ret = false;
      }
    }
  }else{
    Node sc = d_quantEngine->getTermUtil()->isSingularArg(c, pk, arg);
    if( !sc.isNull() ){
      if( hasConst( tnp, sc ) ){
        Trace("sygus-sb-simple") << "  sb-simple : " << c << " is singular arg " << arg << " of " << pk << ", evaluating to " << sc << "..." << std::endl;
        ret = false;
      }
    }
  }
  if( ret ){
    ReqTrie rt;
    Assert( rt.empty() );
    Node max_c = d_quantEngine->getTermUtil()->getTypeMaxValue(c.getType());
    Node zero_c = d_quantEngine->getTermUtil()->getTypeValue(c.getType(), 0);
    Node one_c = d_quantEngine->getTermUtil()->getTypeValue(c.getType(), 1);
    if( pk==XOR || pk==BITVECTOR_XOR ){
      if( c==max_c ){
        rt.d_req_kind = pk==XOR ? NOT : BITVECTOR_NOT;
      }
    }else if( pk==ITE ){
      if( arg==0 ){
        if( c==max_c ){
          rt.d_children[2].d_req_type = tnp;
        }else if( c==zero_c ){
          rt.d_children[1].d_req_type = tnp;
        }
      }
    }else if( pk==STRING_SUBSTR ){
      if( c==one_c ){
        rt.d_req_kind = STRING_CHARAT;
        rt.d_children[0].d_req_type = getArgType( pdt[pc], 0 );
        rt.d_children[1].d_req_type = getArgType( pdt[pc], 1 );
      }
    }
    if( !rt.empty() ){
      //check if satisfied
      if( rt.satisfiedBy( this, tnp ) ){
        Trace("sygus-sb-simple") << "  sb-simple : do not consider const " << c << " as arg " << arg << " of " << pk;
        Trace("sygus-sb-simple") << " in " << ((DatatypeType)tnp.toType()).getDatatype().getName() << std::endl;
        //do not need to consider the constant in the search since there are ways to construct equivalent terms
        ret = false;
      }
    }
  }
  // TODO : cache?
  return ret;
}

int TermDbSygus::solveForArgument( TypeNode tn, unsigned cindex, unsigned arg ) {
  // FIXME
  return -1;  // TODO : if using, modify considerArgKind above
  Assert( isRegistered( tn ) );
  const Datatype& dt = ((DatatypeType)(tn).toType()).getDatatype();
  Assert( cindex<dt.getNumConstructors() );
  Assert( arg<dt[cindex].getNumArgs() );
  Kind nk = getConsNumKind( tn, cindex );
  TypeNode tnc = getArgType( dt[cindex], arg );
  const Datatype& cdt = ((DatatypeType)(tnc).toType()).getDatatype();

  ReqTrie rt;
  Assert( rt.empty() );
  int solve_ret = -1;
  if( nk==MINUS || nk==BITVECTOR_SUB ){
    if( dt[cindex].getNumArgs()==2 && arg==0 ){
      TypeNode tnco = getArgType( dt[cindex], 1 );
      Node builtin = d_quantEngine->getTermUtil()->getTypeValue(
          sygusToBuiltinType(tnc), 0);
      solve_ret = getConstConsNum( tn, builtin );
      if( solve_ret!=-1 ){
        // t - s    ----->  ( 0 - s ) + t
        rt.d_req_kind = nk == MINUS ? PLUS : BITVECTOR_PLUS;
        rt.d_children[0].d_req_type = tn; // avoid?
        rt.d_children[0].d_req_kind = nk;
        rt.d_children[0].d_children[0].d_req_const = builtin;
        rt.d_children[0].d_children[0].d_req_type = tnco;
        rt.d_children[1].d_req_type = tnc;
        // TODO : this can be made more general for multiple type grammars to remove MINUS entirely 
      }
    }
  }
  
  if( !rt.empty() ){
    Assert( solve_ret>=0 );
    Assert( solve_ret<=(int)cdt.getNumConstructors() );
    //check if satisfied
    if( rt.satisfiedBy( this, tn ) ){
      Trace("sygus-sb-simple") << "  sb-simple : ONLY consider " << cdt[solve_ret].getSygusOp() << " as arg " << arg << " of " << nk;
      Trace("sygus-sb-simple") << " in " << ((DatatypeType)tn.toType()).getDatatype().getName() << std::endl;
      return solve_ret;
    }
  }
  
  return -1;
}

void TermDbSygus::registerSygusType( TypeNode tn ) {
  std::map< TypeNode, TypeNode >::iterator itr = d_register.find( tn );
  if( itr==d_register.end() ){
    d_register[tn] = TypeNode::null();
    if( tn.isDatatype() ){
      const Datatype& dt = ((DatatypeType)(tn).toType()).getDatatype();
      Trace("sygus-db") << "Register type " << dt.getName() << "..." << std::endl;
      TypeNode btn = TypeNode::fromType( dt.getSygusType() );
      d_register[tn] = btn;
      if( !d_register[tn].isNull() ){
        // get the sygus variable list
        Node var_list = Node::fromExpr( dt.getSygusVarList() );
        if( !var_list.isNull() ){
          for( unsigned j=0; j<var_list.getNumChildren(); j++ ){
            Node sv = var_list[j];
            SygusVarNumAttribute svna;
            sv.setAttribute( svna, j );
            d_var_list[tn].push_back( sv );
          }
        }else{
          // no arguments to synthesis functions
        }
        //iterate over constructors
        for( unsigned i=0; i<dt.getNumConstructors(); i++ ){
          Expr sop = dt[i].getSygusOp();
          Assert( !sop.isNull() );
          Node n = Node::fromExpr( sop );
          Trace("sygus-db") << "  Operator #" << i << " : " << sop;
          if( sop.getKind() == kind::BUILTIN ){
            Kind sk = NodeManager::operatorToKind( n );
            Trace("sygus-db") << ", kind = " << sk;
            d_kinds[tn][sk] = i;
            d_arg_kind[tn][i] = sk;
          }else if( sop.isConst() ){
            Trace("sygus-db") << ", constant";
            d_consts[tn][n] = i;
            d_arg_const[tn][i] = n;
          }
          d_ops[tn][n] = i;
          d_arg_ops[tn][i] = n;
          Trace("sygus-db") << std::endl;
        }
        //register connected types
        for( unsigned i=0; i<dt.getNumConstructors(); i++ ){
          for( unsigned j=0; j<dt[i].getNumArgs(); j++ ){
            registerSygusType( getArgType( dt[i], j ) );
          }
        }
      }
    }
  }
}

void TermDbSygus::registerEnumerator(Node e,
                                     Node f,
                                     CegConjecture* conj,
                                     bool mkActiveGuard)
{
  Assert(d_enum_to_conjecture.find(e) == d_enum_to_conjecture.end());
  Trace("sygus-db") << "Register measured term : " << e << std::endl;
  d_enum_to_conjecture[e] = conj;
  d_enum_to_synth_fun[e] = f;
  if( mkActiveGuard ){
    // make the guard
    Node eg = Rewriter::rewrite( NodeManager::currentNM()->mkSkolem( "eG", NodeManager::currentNM()->booleanType() ) );
    eg = d_quantEngine->getValuation().ensureLiteral( eg );
    AlwaysAssert( !eg.isNull() );
    d_quantEngine->getOutputChannel().requirePhase( eg, true );
    //add immediate lemma
    Node lem = NodeManager::currentNM()->mkNode( OR, eg, eg.negate() );
    Trace("cegqi-lemma") << "Cegqi::Lemma : enumerator : " << lem << std::endl;
    d_quantEngine->getOutputChannel().lemma( lem );
    d_enum_to_active_guard[e] = eg;
  }
}

bool TermDbSygus::isEnumerator(Node e) const
{
  return d_enum_to_conjecture.find(e) != d_enum_to_conjecture.end();
}

CegConjecture* TermDbSygus::getConjectureForEnumerator(Node e)
{
  std::map<Node, CegConjecture*>::iterator itm = d_enum_to_conjecture.find(e);
  if (itm != d_enum_to_conjecture.end()) {
    return itm->second;
  }else{
    return NULL;
  }
}

Node TermDbSygus::getSynthFunForEnumerator(Node e)
{
  std::map<Node, Node>::iterator itsf = d_enum_to_synth_fun.find(e);
  if (itsf != d_enum_to_synth_fun.end())
  {
    return itsf->second;
  }
  else
  {
    return Node::null();
  }
}

Node TermDbSygus::getActiveGuardForEnumerator(Node e)
{
  std::map<Node, Node>::iterator itag = d_enum_to_active_guard.find(e);
  if (itag != d_enum_to_active_guard.end()) {
    return itag->second;
  }else{
    return Node::null();
  }
}

void TermDbSygus::getEnumerators(std::vector<Node>& mts)
{
  for (std::map<Node, CegConjecture*>::iterator itm =
           d_enum_to_conjecture.begin();
       itm != d_enum_to_conjecture.end(); ++itm) {
    mts.push_back( itm->first );
  }
}

bool TermDbSygus::isRegistered( TypeNode tn ) {
  return d_register.find( tn )!=d_register.end();
}

TypeNode TermDbSygus::sygusToBuiltinType( TypeNode tn ) {
  Assert( isRegistered( tn ) );
  return d_register[tn];
}

void TermDbSygus::computeMinTypeDepthInternal( TypeNode root_tn, TypeNode tn, unsigned type_depth ) {
  std::map< TypeNode, unsigned >::iterator it = d_min_type_depth[root_tn].find( tn );
  if( it==d_min_type_depth[root_tn].end() || type_depth<it->second ){
    d_min_type_depth[root_tn][tn] = type_depth;
    Assert( tn.isDatatype() );
    const Datatype& dt = ((DatatypeType)(tn).toType()).getDatatype();
    //compute for connected types
    for( unsigned i=0; i<dt.getNumConstructors(); i++ ){
      for( unsigned j=0; j<dt[i].getNumArgs(); j++ ){
        computeMinTypeDepthInternal( root_tn, getArgType( dt[i], j ), type_depth+1 );
      }
    }
  }
}
  
unsigned TermDbSygus::getMinTypeDepth( TypeNode root_tn, TypeNode tn ){
  std::map< TypeNode, unsigned >::iterator it = d_min_type_depth[root_tn].find( tn );
  if( it==d_min_type_depth[root_tn].end() ){
    computeMinTypeDepthInternal( root_tn, root_tn, 0 );
    Assert( d_min_type_depth[root_tn].find( tn )!=d_min_type_depth[root_tn].end() );  
    return d_min_type_depth[root_tn][tn];
  }else{
    return it->second;
  }
}

unsigned TermDbSygus::getMinTermSize( TypeNode tn ) {
  Assert( isRegistered( tn ) );
  std::map< TypeNode, unsigned >::iterator it = d_min_term_size.find( tn );
  if( it==d_min_term_size.end() ){
    const Datatype& dt = ((DatatypeType)(tn).toType()).getDatatype();
    for( unsigned i=0; i<dt.getNumConstructors(); i++ ){
      if (dt[i].getNumArgs() == 0)
      {
        d_min_term_size[tn] = 0;
        return 0;
      }
    }
    // TODO : improve
    d_min_term_size[tn] = 1;
    return 1;
  }else{
    return it->second;
  }
}

unsigned TermDbSygus::getMinConsTermSize( TypeNode tn, unsigned cindex ) {
  Assert( isRegistered( tn ) );
  std::map< unsigned, unsigned >::iterator it = d_min_cons_term_size[tn].find( cindex );
  if( it==d_min_cons_term_size[tn].end() ){
    const Datatype& dt = ((DatatypeType)(tn).toType()).getDatatype();
    Assert( cindex<dt.getNumConstructors() );
    unsigned ret = 0;
    if( dt[cindex].getNumArgs()>0 ){
      ret = 1;
      for( unsigned i=0; i<dt[cindex].getNumArgs(); i++ ){
        ret += getMinTermSize( getArgType( dt[cindex], i ) );
      }
    }
    d_min_cons_term_size[tn][cindex] = ret;
    return ret;
  }else{
    return it->second;
  }
}

unsigned TermDbSygus::getSelectorWeight(TypeNode tn, Node sel)
{
  std::map<TypeNode, std::map<Node, unsigned> >::iterator itsw =
      d_sel_weight.find(tn);
  if (itsw == d_sel_weight.end())
  {
    d_sel_weight[tn].clear();
    itsw = d_sel_weight.find(tn);
    Type t = tn.toType();
    const Datatype& dt = static_cast<DatatypeType>(t).getDatatype();
    Trace("sygus-db") << "Compute selector weights for " << dt.getName()
                      << std::endl;
    for (unsigned i = 0, size = dt.getNumConstructors(); i < size; i++)
    {
      unsigned cw = dt[i].getWeight();
      for (unsigned j = 0, size2 = dt[i].getNumArgs(); j < size2; j++)
      {
        Node csel = Node::fromExpr(dt[i].getSelectorInternal(t, j));
        std::map<Node, unsigned>::iterator its = itsw->second.find(csel);
        if (its == itsw->second.end() || cw < its->second)
        {
          d_sel_weight[tn][csel] = cw;
          Trace("sygus-db") << "  w(" << csel << ") <= " << cw << std::endl;
        }
      }
    }
  }
  Assert(itsw->second.find(sel) != itsw->second.end());
  return itsw->second[sel];
}

int TermDbSygus::getKindConsNum( TypeNode tn, Kind k ) {
  Assert( isRegistered( tn ) );
  std::map< TypeNode, std::map< Kind, int > >::iterator itt = d_kinds.find( tn );
  if( itt!=d_kinds.end() ){
    std::map< Kind, int >::iterator it = itt->second.find( k );
    if( it!=itt->second.end() ){
      return it->second;
    }
  }
  return -1;
}

int TermDbSygus::getConstConsNum( TypeNode tn, Node n ){
  Assert( isRegistered( tn ) );
  std::map< TypeNode, std::map< Node, int > >::iterator itt = d_consts.find( tn );
  if( itt!=d_consts.end() ){
    std::map< Node, int >::iterator it = itt->second.find( n );
    if( it!=itt->second.end() ){
      return it->second;
    }
  }
  return -1;
}

int TermDbSygus::getOpConsNum( TypeNode tn, Node n ) {
  std::map< Node, int >::iterator it = d_ops[tn].find( n );
  if( it!=d_ops[tn].end() ){
    return it->second;
  }else{
    return -1;
  }
}

bool TermDbSygus::hasKind( TypeNode tn, Kind k ) {
  return getKindConsNum( tn, k )!=-1;
}
bool TermDbSygus::hasConst( TypeNode tn, Node n ) {
  return getConstConsNum( tn, n )!=-1;
}
bool TermDbSygus::hasOp( TypeNode tn, Node n ) {
  return getOpConsNum( tn, n )!=-1;
}

Node TermDbSygus::getConsNumOp( TypeNode tn, int i ) {
  Assert( isRegistered( tn ) );
  std::map< TypeNode, std::map< int, Node > >::iterator itt = d_arg_ops.find( tn );
  if( itt!=d_arg_ops.end() ){
    std::map< int, Node >::iterator itn = itt->second.find( i );
    if( itn!=itt->second.end() ){
      return itn->second;
    }
  }
  return Node::null();
}

Node TermDbSygus::getConsNumConst( TypeNode tn, int i ) {
  Assert( isRegistered( tn ) );
  std::map< TypeNode, std::map< int, Node > >::iterator itt = d_arg_const.find( tn );
  if( itt!=d_arg_const.end() ){
    std::map< int, Node >::iterator itn = itt->second.find( i );
    if( itn!=itt->second.end() ){
      return itn->second;
    }
  }
  return Node::null();
}

Kind TermDbSygus::getConsNumKind( TypeNode tn, int i ) {
  Assert( isRegistered( tn ) );
  std::map< TypeNode, std::map< int, Kind > >::iterator itt = d_arg_kind.find( tn );
  if( itt!=d_arg_kind.end() ){
    std::map< int, Kind >::iterator itk = itt->second.find( i );
    if( itk!=itt->second.end() ){
      return itk->second;
    }
  }
  return UNDEFINED_KIND;
}

bool TermDbSygus::isKindArg( TypeNode tn, int i ) {
  return getConsNumKind( tn, i )!=UNDEFINED_KIND;
}

bool TermDbSygus::isConstArg( TypeNode tn, int i ) {
  Assert( isRegistered( tn ) );
  std::map< TypeNode, std::map< int, Node > >::iterator itt = d_arg_const.find( tn );
  if( itt!=d_arg_const.end() ){
    return itt->second.find( i )!=itt->second.end();
  }else{
    return false;
  }
}

TypeNode TermDbSygus::getArgType(const DatatypeConstructor& c, unsigned i)
{
  Assert(i < c.getNumArgs());
  return TypeNode::fromType( ((SelectorType)c[i].getType()).getRangeType() );
}

/** get first occurrence */
int TermDbSygus::getFirstArgOccurrence( const DatatypeConstructor& c, TypeNode tn ) {
  for( unsigned i=0; i<c.getNumArgs(); i++ ){
    TypeNode tni = getArgType( c, i );
    if( tni==tn ){
      return i;
    }
  }
  return -1;
}

bool TermDbSygus::isTypeMatch( const DatatypeConstructor& c1, const DatatypeConstructor& c2 ) {
  if( c1.getNumArgs()!=c2.getNumArgs() ){
    return false;
  }else{
    for( unsigned i=0; i<c1.getNumArgs(); i++ ){
      if( getArgType( c1, i )!=getArgType( c2, i ) ){
        return false;
      }
    }
    return true;
  }
}

Node TermDbSygus::minimizeBuiltinTerm( Node n ) {
  if( ( n.getKind()==EQUAL || n.getKind()==LEQ || n.getKind()==LT || n.getKind()==GEQ || n.getKind()==GT ) &&
      ( n[0].getType().isInteger() || n[0].getType().isReal() ) ){
    bool changed = false;
    std::vector< Node > mon[2];
    for( unsigned r=0; r<2; r++ ){
      unsigned ro = r==0 ? 1 : 0;
      Node c;
      Node nc;
      if( n[r].getKind()==PLUS ){
        for( unsigned i=0; i<n[r].getNumChildren(); i++ ){
          if (ArithMSum::getMonomial(n[r][i], c, nc)
              && c.getConst<Rational>().isNegativeOne())
          {
            mon[ro].push_back( nc );
            changed = true;
          }else{
            if( !n[r][i].isConst() || !n[r][i].getConst<Rational>().isZero() ){
              mon[r].push_back( n[r][i] );
            }
          }
        }
      }else{
        if (ArithMSum::getMonomial(n[r], c, nc)
            && c.getConst<Rational>().isNegativeOne())
        {
          mon[ro].push_back( nc );
          changed = true;
        }else{
          if( !n[r].isConst() || !n[r].getConst<Rational>().isZero() ){
            mon[r].push_back( n[r] );
          }
        }
      }
    }
    if( changed ){
      Node nn[2];
      for( unsigned r=0; r<2; r++ ){
        nn[r] = mon[r].size()==0 ? NodeManager::currentNM()->mkConst( Rational(0) ) : ( mon[r].size()==1 ? mon[r][0] : NodeManager::currentNM()->mkNode( PLUS, mon[r] ) );
      }
      return NodeManager::currentNM()->mkNode( n.getKind(), nn[0], nn[1] );
    }
  }
  return n;
}

Node TermDbSygus::expandBuiltinTerm( Node t ){
  if( t.getKind()==EQUAL ){
    if( t[0].getType().isReal() ){
      return NodeManager::currentNM()->mkNode( AND, NodeManager::currentNM()->mkNode( LEQ, t[0], t[1] ),
                                                    NodeManager::currentNM()->mkNode( LEQ, t[1], t[0] ) );
    }else if( t[0].getType().isBoolean() ){
      return NodeManager::currentNM()->mkNode( OR, NodeManager::currentNM()->mkNode( AND, t[0], t[1] ),
                                                   NodeManager::currentNM()->mkNode( AND, t[0].negate(), t[1].negate() ) );
    }
  }else if( t.getKind()==ITE && t.getType().isBoolean() ){
    return NodeManager::currentNM()->mkNode( OR, NodeManager::currentNM()->mkNode( AND, t[0], t[1] ),
                                                 NodeManager::currentNM()->mkNode( AND, t[0].negate(), t[2] ) );
  }
  return Node::null();
}


Kind TermDbSygus::getComparisonKind( TypeNode tn ) {
  if( tn.isInteger() || tn.isReal() ){
    return LT;
  }else if( tn.isBitVector() ){
    return BITVECTOR_ULT;
  }else{
    return UNDEFINED_KIND;
  }
}

Kind TermDbSygus::getPlusKind( TypeNode tn, bool is_neg ) {
  if( tn.isInteger() || tn.isReal() ){
    return is_neg ? MINUS : PLUS;
  }else if( tn.isBitVector() ){
    return is_neg ? BITVECTOR_SUB : BITVECTOR_PLUS;
  }else{
    return UNDEFINED_KIND;
  }
}

Node TermDbSygus::getSemanticSkolem( TypeNode tn, Node n, bool doMk ){
  std::map< Node, Node >::iterator its = d_semantic_skolem[tn].find( n );
  if( its!=d_semantic_skolem[tn].end() ){
    return its->second;
  }else if( doMk ){
    Node ss = NodeManager::currentNM()->mkSkolem( "sem", tn, "semantic skolem for sygus" );
    d_semantic_skolem[tn][n] = ss;
    return ss;
  }else{
    return Node::null();
  }
}

bool TermDbSygus::involvesDivByZero( Node n, std::map< Node, bool >& visited ){
  if( visited.find( n )==visited.end() ){
    visited[n] = true;
    Kind k = n.getKind();
    if( k==DIVISION || k==DIVISION_TOTAL || k==INTS_DIVISION || k==INTS_DIVISION_TOTAL || 
        k==INTS_MODULUS || k==INTS_MODULUS_TOTAL ){
      if( n[1].isConst() ){
        if (n[1]
            == d_quantEngine->getTermUtil()->getTypeValue(n[1].getType(), 0))
        {
          return true;
        }
      }else{
        // if it has free variables it might be a non-zero constant
        if( !hasFreeVar( n[1] ) ){
          return true;
        }
      }
    }
    for( unsigned i=0; i<n.getNumChildren(); i++ ){
      if( involvesDivByZero( n[i], visited ) ){
        return true;
      }
    }
  }
  return false;
}

bool TermDbSygus::involvesDivByZero( Node n ) {
  std::map< Node, bool > visited;
  return involvesDivByZero( n, visited );
}

void doStrReplace(std::string& str, const std::string& oldStr, const std::string& newStr){
  size_t pos = 0;
  while((pos = str.find(oldStr, pos)) != std::string::npos){
     str.replace(pos, oldStr.length(), newStr);
     pos += newStr.length();
  }
}

Kind TermDbSygus::getOperatorKind( Node op ) {
  Assert( op.getKind()!=BUILTIN );
  if (op.getKind() == LAMBDA)
  {
    // we use APPLY_UF instead of APPLY, since the rewriter for APPLY_UF
    // does beta-reduction but does not for APPLY
    return APPLY_UF;
  }else{
    TypeNode tn = op.getType();
    if( tn.isConstructor() ){
      return APPLY_CONSTRUCTOR;
    }
    else if (tn.isSelector())
    {
      return APPLY_SELECTOR;
    }
    else if (tn.isTester())
    {
      return APPLY_TESTER;
    }
    else if (tn.isFunction())
    {
      return APPLY_UF;
    }
    return NodeManager::operatorToKind(op);
  }
}

Node TermDbSygus::getAnchor( Node n ) {
  if( n.getKind()==APPLY_SELECTOR_TOTAL ){
    return getAnchor( n[0] );
  }else{
    return n;
  }
}

unsigned TermDbSygus::getAnchorDepth( Node n ) {
  if( n.getKind()==APPLY_SELECTOR_TOTAL ){
    return 1+getAnchorDepth( n[0] );
  }else{
    return 0;
  }
}


void TermDbSygus::registerEvalTerm( Node n ) {
  if( options::sygusDirectEval() ){
    if( n.getKind()==APPLY_UF && !n.getType().isBoolean() ){
      TypeNode tn = n[0].getType();
      if( tn.isDatatype() ){
        const Datatype& dt = ((DatatypeType)(tn).toType()).getDatatype();
        if( dt.isSygus() ){
          Node f = n.getOperator();
          if( n[0].getKind()!=APPLY_CONSTRUCTOR ){
            if (d_eval_processed.find(n) == d_eval_processed.end())
            {
              Trace("sygus-eager")
                  << "TermDbSygus::eager: Register eval term : " << n
                  << std::endl;
              d_eval_processed.insert(n);
              d_evals[n[0]].push_back(n);
              TypeNode tn = n[0].getType();
              Assert(tn.isDatatype());
              const Datatype& dt = ((DatatypeType)(tn).toType()).getDatatype();
              Node var_list = Node::fromExpr(dt.getSygusVarList());
              Assert(dt.isSygus());
              d_eval_args[n[0]].push_back(std::vector<Node>());
              bool isConst = true;
              for (unsigned j = 1; j < n.getNumChildren(); j++)
              {
                d_eval_args[n[0]].back().push_back(n[j]);
                if (!n[j].isConst())
                {
                  isConst = false;
                }
              }
              d_eval_args_const[n[0]].push_back(isConst);
              Node a = getAnchor(n[0]);
              d_subterms[a][n[0]] = true;
            }
          }
        }
      }    
    }
  }
}

void TermDbSygus::registerModelValue( Node a, Node v, std::vector< Node >& terms, std::vector< Node >& vals, std::vector< Node >& exps ) {
  std::map< Node, std::map< Node, bool > >::iterator its = d_subterms.find( a );
  if( its!=d_subterms.end() ){
    Trace("sygus-eager") << "registerModelValue : " << a << ", has " << its->second.size() << " registered subterms." << std::endl;
    for( std::map< Node, bool >::iterator itss = its->second.begin(); itss != its->second.end(); ++itss ){
      Node n = itss->first;
      Trace("sygus-eager-debug") << "...process : " << n << std::endl;
      std::map< Node, std::vector< std::vector< Node > > >::iterator it = d_eval_args.find( n );
      if( it!=d_eval_args.end() && !it->second.empty() ){
        TNode at = a;
        TNode vt = v;
        Node vn = n.substitute( at, vt );
        vn = Rewriter::rewrite( vn );
        unsigned start = d_node_mv_args_proc[n][vn];
        // get explanation in terms of testers
        std::vector< Node > antec_exp;
        d_syexp->getExplanationForConstantEquality(n, vn, antec_exp);
        Node antec = antec_exp.size()==1 ? antec_exp[0] : NodeManager::currentNM()->mkNode( kind::AND, antec_exp );
        //Node antec = n.eqNode( vn );
        TypeNode tn = n.getType();
        Assert( tn.isDatatype() );
        const Datatype& dt = ((DatatypeType)(tn).toType()).getDatatype();
        Assert( dt.isSygus() );
        Trace("sygus-eager") << "TermDbSygus::eager: Register model value : " << vn << " for " << n << std::endl;
        Trace("sygus-eager") << "...it has " << it->second.size() << " evaluations, already processed " << start << "." << std::endl;
        Node bTerm = sygusToBuiltin( vn, tn );
        Trace("sygus-eager") << "Built-in term : " << bTerm << std::endl;
        std::vector< Node > vars;
        Node var_list = Node::fromExpr( dt.getSygusVarList() );
        for( unsigned j=0; j<var_list.getNumChildren(); j++ ){
          vars.push_back( var_list[j] );
        }
        //evaluation children
        std::vector< Node > eval_children;
        eval_children.push_back( Node::fromExpr( dt.getSygusEvaluationFunc() ) );
        eval_children.push_back( n );
        //for each evaluation
        for( unsigned i=start; i<it->second.size(); i++ ){
          Node res;
          Node expn;
          // unfold?
          bool do_unfold = false;
          if( options::sygusUnfoldBool() ){
            if( bTerm.getKind()==ITE || bTerm.getType().isBoolean() ){
              do_unfold = true;
            }
          }
          if( do_unfold ){
            // TODO : this is replicated for different values, possibly do better caching
            std::map< Node, Node > vtm; 
            std::vector< Node > exp;
            vtm[n] = vn;
            eval_children.insert( eval_children.end(), it->second[i].begin(), it->second[i].end() );
            Node eval_fun = NodeManager::currentNM()->mkNode( kind::APPLY_UF, eval_children );
            eval_children.resize( 2 );  
            res = unfold( eval_fun, vtm, exp );
            expn = exp.size()==1 ? exp[0] : NodeManager::currentNM()->mkNode( kind::AND, exp );
          }else{

            EvalSygusInvarianceTest esit;
            eval_children.insert( eval_children.end(), it->second[i].begin(), it->second[i].end() );
            Node conj =
                NodeManager::currentNM()->mkNode(kind::APPLY_UF, eval_children);
            eval_children[1] = vn;
            Node eval_fun = NodeManager::currentNM()->mkNode( kind::APPLY_UF, eval_children );
            res = evaluateWithUnfolding(eval_fun);
            esit.init(conj, n, res);
            eval_children.resize( 2 );  
            eval_children[1] = n;
            
            //evaluate with minimal explanation
            std::vector< Node > mexp;
            d_syexp->getExplanationFor(n, vn, mexp, esit);
            Assert( !mexp.empty() );
            expn = mexp.size()==1 ? mexp[0] : NodeManager::currentNM()->mkNode( kind::AND, mexp );
            
            //if all constant, we can use evaluation to minimize the explanation
            //Assert( i<d_eval_args_const[n].size() );
            //if( d_eval_args_const[n][i] ){
              /*
              std::map< Node, Node > vtm; 
              std::map< Node, Node > visited; 
              std::map< Node, std::vector< Node > > exp;
              vtm[n] = vn;
              res = crefEvaluate( eval_fun, vtm, visited, exp );
              Assert( !exp[eval_fun].empty() );
              expn = exp[eval_fun].size()==1 ? exp[eval_fun][0] : NodeManager::currentNM()->mkNode( kind::AND, exp[eval_fun] );
              */
              /*
            //otherwise, just do a substitution
            }else{
              Assert( vars.size()==it->second[i].size() );
              res = bTerm.substitute( vars.begin(), vars.end(), it->second[i].begin(), it->second[i].end() );
              res = Rewriter::rewrite( res );
              expn = antec;
            }
            */
          }
          Assert( !res.isNull() );
          terms.push_back( d_evals[n][i] );
          vals.push_back( res );
          exps.push_back( expn );
          Trace("sygus-eager") << "Conclude : " << d_evals[n][i] << " == " << res << ", cref eval = " << d_eval_args_const[n][i] << std::endl;
          Trace("sygus-eager") << "   from " << expn << std::endl;
        }
        d_node_mv_args_proc[n][vn] = it->second.size();
      }
    }
  }
}

Node TermDbSygus::unfold( Node en, std::map< Node, Node >& vtm, std::vector< Node >& exp, bool track_exp ) {
  if( en.getKind()==kind::APPLY_UF ){
    Trace("sygus-db-debug") << "Unfold : " << en << std::endl;
    Node ev = en[0];
    if( track_exp ){
      std::map< Node, Node >::iterator itv = vtm.find( en[0] );
      if( itv!=vtm.end() ){
        ev = itv->second;
      }else{
        Assert( false );
      }
      Assert( en[0].getType()==ev.getType() );
      Assert( ev.isConst() );
    }
    Assert( ev.getKind()==kind::APPLY_CONSTRUCTOR );
    std::vector< Node > args;
    for( unsigned i=1; i<en.getNumChildren(); i++ ){
      args.push_back( en[i] );
    }
    const Datatype& dt = ((DatatypeType)(ev.getType()).toType()).getDatatype();
    unsigned i = Datatype::indexOf( ev.getOperator().toExpr() );
    if( track_exp ){
      //explanation
      Node ee = NodeManager::currentNM()->mkNode( kind::APPLY_TESTER, Node::fromExpr( dt[i].getTester() ), en[0] );
      if( std::find( exp.begin(), exp.end(), ee )==exp.end() ){
        exp.push_back( ee );
      }
    }
    Assert( !dt.isParametric() );
    std::map< int, Node > pre;
    for( unsigned j=0; j<dt[i].getNumArgs(); j++ ){
      std::vector< Node > cc;
      //get the evaluation argument for the selector
      Type rt = dt[i][j].getRangeType();
      const Datatype & ad = ((DatatypeType)dt[i][j].getRangeType()).getDatatype();
      cc.push_back( Node::fromExpr( ad.getSygusEvaluationFunc() ) );
      Node s;
      if( en[0].getKind()==kind::APPLY_CONSTRUCTOR ){
        s = en[0][j];
      }else{
        s = NodeManager::currentNM()->mkNode( kind::APPLY_SELECTOR_TOTAL, dt[i].getSelectorInternal( en[0].getType().toType(), j ), en[0] );
      }
      cc.push_back( s );
      if( track_exp ){
        //update vtm map
        vtm[s] = ev[j];
      }
      cc.insert( cc.end(), args.begin(), args.end() );
      pre[j] = NodeManager::currentNM()->mkNode( kind::APPLY_UF, cc );
    }
    std::map< TypeNode, int > var_count; 
    Node ret = mkGeneric( dt, i, var_count, pre );
    // if it is a variable, apply the substitution
    if( ret.getKind()==kind::BOUND_VARIABLE ){
      Assert( ret.hasAttribute(SygusVarNumAttribute()) );
      int i = ret.getAttribute(SygusVarNumAttribute());
      Assert( Node::fromExpr( dt.getSygusVarList() )[i]==ret );
      ret = args[i];
    }
    else
    {
      ret = Rewriter::rewrite(ret);
    }
    return ret;
  }else{
    Assert( en.isConst() );
  }
  return en;
}


Node TermDbSygus::getEagerUnfold( Node n, std::map< Node, Node >& visited ) {
  std::map< Node, Node >::iterator itv = visited.find( n );
  if( itv==visited.end() ){
    Trace("cegqi-eager-debug") << "getEagerUnfold " << n << std::endl;
    Node ret;
    if( n.getKind()==APPLY_UF ){
      TypeNode tn = n[0].getType();
      Trace("cegqi-eager-debug") << "check " << n[0].getType() << std::endl;
      if( tn.isDatatype() ){
        const Datatype& dt = ((DatatypeType)(tn).toType()).getDatatype();
        if( dt.isSygus() ){ 
          Trace("cegqi-eager") << "Unfold eager : " << n << std::endl;
          Node bTerm = sygusToBuiltin( n[0], tn );
          Trace("cegqi-eager") << "Built-in term : " << bTerm << std::endl;
          std::vector< Node > vars;
          std::vector< Node > subs;
          Node var_list = Node::fromExpr( dt.getSygusVarList() );
          Assert( var_list.getNumChildren()+1==n.getNumChildren() );
          for( unsigned j=0; j<var_list.getNumChildren(); j++ ){
            vars.push_back( var_list[j] );
          }
          for( unsigned j=1; j<n.getNumChildren(); j++ ){
            Node nc = getEagerUnfold( n[j], visited );
            subs.push_back( nc );
            Assert(subs[j - 1].getType().isComparableTo(
                var_list[j - 1].getType()));
          }
          Assert( vars.size()==subs.size() );
          bTerm = bTerm.substitute( vars.begin(), vars.end(), subs.begin(), subs.end() );
          Trace("cegqi-eager") << "Built-in term after subs : " << bTerm << std::endl;
          Trace("cegqi-eager-debug") << "Types : " << bTerm.getType() << " " << n.getType() << std::endl;
          Assert(n.getType().isComparableTo(bTerm.getType()));
          ret = bTerm; 
        }
      }
    }
    if( ret.isNull() ){
      if( n.getKind()!=FORALL ){
        bool childChanged = false;
        std::vector< Node > children;
        for( unsigned i=0; i<n.getNumChildren(); i++ ){
          Node nc = getEagerUnfold( n[i], visited );
          childChanged = childChanged || n[i]!=nc;
          children.push_back( nc );
        }
        if( childChanged ){
          if( n.getMetaKind() == kind::metakind::PARAMETERIZED ){
            children.insert( children.begin(), n.getOperator() );
          }
          ret = NodeManager::currentNM()->mkNode( n.getKind(), children );
        }
      }
      if( ret.isNull() ){
        ret = n;
      }
    }
    visited[n] = ret;
    return ret;
  }else{
    return itv->second;
  }
}


Node TermDbSygus::evaluateBuiltin( TypeNode tn, Node bn, std::vector< Node >& args ) {
  if( !args.empty() ){
    std::map< TypeNode, std::vector< Node > >::iterator it = d_var_list.find( tn );
    Assert( it!=d_var_list.end() );
    Assert( it->second.size()==args.size() );
    return Rewriter::rewrite( bn.substitute( it->second.begin(), it->second.end(), args.begin(), args.end() ) );
  }else{
    return Rewriter::rewrite( bn );
  }
}

Node TermDbSygus::evaluateWithUnfolding(
    Node n, std::unordered_map<Node, Node, NodeHashFunction>& visited)
{
  std::unordered_map<Node, Node, NodeHashFunction>::iterator it =
      visited.find(n);
  if( it==visited.end() ){
    Node ret = n;
    while( ret.getKind()==APPLY_UF && ret[0].getKind()==APPLY_CONSTRUCTOR ){
      ret = unfold( ret );
    }    
    if( ret.getNumChildren()>0 ){
      std::vector< Node > children;
      if( ret.getMetaKind() == kind::metakind::PARAMETERIZED ){
        children.push_back( ret.getOperator() );
      }
      bool childChanged = false;
      for( unsigned i=0; i<ret.getNumChildren(); i++ ){
        Node nc = evaluateWithUnfolding( ret[i], visited ); 
        childChanged = childChanged || nc!=ret[i];
        children.push_back( nc );
      }
      if( childChanged ){
        ret = NodeManager::currentNM()->mkNode( ret.getKind(), children );
      }
      ret = getExtRewriter()->extendedRewrite(ret);
    }
    visited[n] = ret;
    return ret;
  }else{
    return it->second;
  }
}

Node TermDbSygus::evaluateWithUnfolding( Node n ) {
  std::unordered_map<Node, Node, NodeHashFunction> visited;
  return evaluateWithUnfolding( n, visited );
}

}/* CVC4::theory::quantifiers namespace */
}/* CVC4::theory namespace */
}/* CVC4 namespace */