src/theory/sort_inference.cpp

   1 /*********************                                                        */
   2 /*! \file sort_inference.cpp
   3  ** \verbatim
   4  ** Top contributors (to current version):
   5  **   Andrew Reynolds, Paul Meng, Kshitij Bansal
   6  ** This file is part of the CVC4 project.
   7  ** Copyright (c) 2009-2019 by the authors listed in the file AUTHORS
   8  ** in the top-level source directory) and their institutional affiliations.
   9  ** All rights reserved.  See the file COPYING in the top-level source
  10  ** directory for licensing information.\endverbatim
  11  **
  12  ** \brief Sort inference module
  13  **
  14  ** This class implements sort inference, based on a simple algorithm:
  15  ** First, we assume all functions and predicates have distinct uninterpreted types.
  16  ** One pass is made through the input assertions, while a union-find data structure
  17  ** maintains necessary information regarding constraints on these types.
  18  **/
  19
  20 #include "theory/sort_inference.h"
  21
  22 #include <vector>
  23
  24 #include "options/quantifiers_options.h"
  25 #include "options/smt_options.h"
  26 #include "options/uf_options.h"
  27 #include "proof/proof_manager.h"
  28 #include "theory/rewriter.h"
  29 #include "theory/quantifiers/quant_util.h"
  30
  31 using namespace CVC4;
  32 using namespace std;
  33
  34 namespace CVC4 {
  35
  36 void SortInference::UnionFind::print(const char * c){
  37   for( std::map< int, int >::iterator it = d_eqc.begin(); it != d_eqc.end(); ++it ){
  38     Trace(c) << "s_" << it->first << " = s_" << it->second << ", ";
  39   }
  40   for( unsigned i=0; i<d_deq.size(); i++ ){
  41     Trace(c) << "s_" << d_deq[i].first << " != s_" << d_deq[i].second << ", ";
  42   }
  43   Trace(c) << std::endl;
  44 }
  45 void SortInference::UnionFind::set( UnionFind& c ) {
  46   clear();
  47   for( std::map< int, int >::iterator it = c.d_eqc.begin(); it != c.d_eqc.end(); ++it ){
  48     d_eqc[ it->first ] = it->second;
  49   }
  50   d_deq.insert( d_deq.end(), c.d_deq.begin(), c.d_deq.end() );
  51 }
  52 int SortInference::UnionFind::getRepresentative( int t ){
  53   std::map< int, int >::iterator it = d_eqc.find( t );
  54   if( it==d_eqc.end() || it->second==t ){
  55     return t;
  56   }else{
  57     int rt = getRepresentative( it->second );
  58     d_eqc[t] = rt;
  59     return rt;
  60   }
  61 }
  62 void SortInference::UnionFind::setEqual( int t1, int t2 ){
  63   if( t1!=t2 ){
  64     int rt1 = getRepresentative( t1 );
  65     int rt2 = getRepresentative( t2 );
  66     if( rt1>rt2 ){
  67       d_eqc[rt1] = rt2;
  68     }else{
  69       d_eqc[rt2] = rt1;
  70     }
  71   }
  72 }
  73 bool SortInference::UnionFind::isValid() {
  74   for( unsigned i=0; i<d_deq.size(); i++ ){
  75     if( areEqual( d_deq[i].first, d_deq[i].second ) ){
  76       return false;
  77     }
  78   }
  79   return true;
  80 }
  81
  82
  83 void SortInference::recordSubsort( TypeNode tn, int s ){
  84   s = d_type_union_find.getRepresentative( s );
  85   if( std::find( d_sub_sorts.begin(), d_sub_sorts.end(), s )==d_sub_sorts.end() ){
  86     d_sub_sorts.push_back( s );
  87     d_type_sub_sorts[tn].push_back( s );
  88   }
  89 }
  90
  91 void SortInference::printSort( const char* c, int t ){
  92   int rt = d_type_union_find.getRepresentative( t );
  93   if( d_type_types.find( rt )!=d_type_types.end() ){
  94     Trace(c) << d_type_types[rt];
  95   }else{
  96     Trace(c) << "s_" << rt;
  97   }
  98 }
  99
 100 void SortInference::reset() {
 101   d_sub_sorts.clear();
 102   d_non_monotonic_sorts.clear();
 103   d_type_sub_sorts.clear();
 104   //reset info
 105   d_sortCount = 1;
 106   d_type_union_find.clear();
 107   d_type_types.clear();
 108   d_id_for_types.clear();
 109   d_op_return_types.clear();
 110   d_op_arg_types.clear();
 111   d_var_types.clear();
 112   //for rewriting
 113   d_symbol_map.clear();
 114   d_const_map.clear();
 115 }
 116
 117 void SortInference::initialize(const std::vector<Node>& assertions)
 118 {
 119   Trace("sort-inference-proc") << "Calculating sort inference..." << std::endl;
 120   // process all assertions
 121   std::map<Node, int> visited;
 122   for (const Node& a : assertions)
 123   {
 124     Trace("sort-inference-debug") << "Process " << a << std::endl;
 125     std::map<Node, Node> var_bound;
 126     process(a, var_bound, visited);
 127   }
 128   Trace("sort-inference-proc") << "...done" << std::endl;
 129   for (const std::pair<const Node, int>& rt : d_op_return_types)
 130   {
 131     Trace("sort-inference") << rt.first << " : ";
 132     TypeNode retTn = rt.first.getType();
 133     if (!d_op_arg_types[rt.first].empty())
 134     {
 135       Trace("sort-inference") << "( ";
 136       for (size_t i = 0; i < d_op_arg_types[rt.first].size(); i++)
 137       {
 138         recordSubsort(retTn[i], d_op_arg_types[rt.first][i]);
 139         printSort("sort-inference", d_op_arg_types[rt.first][i]);
 140         Trace("sort-inference") << " ";
 141       }
 142       Trace("sort-inference") << ") -> ";
 143       retTn = retTn[(int)retTn.getNumChildren() - 1];
 144     }
 145     recordSubsort(retTn, rt.second);
 146     printSort("sort-inference", rt.second);
 147     Trace("sort-inference") << std::endl;
 148   }
 149   for (std::pair<const Node, std::map<Node, int> >& vt : d_var_types)
 150   {
 151     Trace("sort-inference")
 152         << "Quantified formula : " << vt.first << " : " << std::endl;
 153     for (const Node& v : vt.first[0])
 154     {
 155       recordSubsort(v.getType(), vt.second[v]);
 156       printSort("sort-inference", vt.second[v]);
 157       Trace("sort-inference") << std::endl;
 158     }
 159     Trace("sort-inference") << std::endl;
 160   }
 161
 162   // determine monotonicity of sorts
 163   Trace("sort-inference-proc")
 164       << "Calculating monotonicty for subsorts..." << std::endl;
 165   std::map<Node, std::map<int, bool> > visitedm;
 166   for (const Node& a : assertions)
 167   {
 168     Trace("sort-inference-debug")
 169         << "Process monotonicity for " << a << std::endl;
 170     std::map<Node, Node> var_bound;
 171     processMonotonic(a, true, true, var_bound, visitedm);
 172   }
 173   Trace("sort-inference-proc") << "...done" << std::endl;
 174
 175   Trace("sort-inference") << "We have " << d_sub_sorts.size()
 176                           << " sub-sorts : " << std::endl;
 177   for (unsigned i = 0, size = d_sub_sorts.size(); i < size; i++)
 178   {
 179     printSort("sort-inference", d_sub_sorts[i]);
 180     if (d_type_types.find(d_sub_sorts[i]) != d_type_types.end())
 181     {
 182       Trace("sort-inference") << " is interpreted." << std::endl;
 183     }
 184     else if (d_non_monotonic_sorts.find(d_sub_sorts[i])
 185              == d_non_monotonic_sorts.end())
 186     {
 187       Trace("sort-inference") << " is monotonic." << std::endl;
 188     }
 189     else
 190     {
 191       Trace("sort-inference") << " is not monotonic." << std::endl;
 192     }
 193   }
 194 }
 195
 196 Node SortInference::simplify(Node n,
 197                              std::map<Node, Node>& model_replace_f,
 198                              std::map<Node, std::map<TypeNode, Node> >& visited)
 199 {
 200   Trace("sort-inference-debug") << "Simplify " << n << std::endl;
 201   std::map<Node, Node> var_bound;
 202   TypeNode tnn;
 203   Node ret = simplifyNode(n, var_bound, tnn, model_replace_f, visited);
 204   ret = theory::Rewriter::rewrite(ret);
 205   return ret;
 206 }
 207
 208 void SortInference::getNewAssertions(std::vector<Node>& new_asserts)
 209 {
 210   NodeManager* nm = NodeManager::currentNM();
 211   // now, ensure constants are distinct
 212   for (const std::pair<const TypeNode, std::map<Node, Node> >& cm : d_const_map)
 213   {
 214     std::vector<Node> consts;
 215     for (const std::pair<const Node, Node>& c : cm.second)
 216     {
 217       Assert(c.first.isConst());
 218       consts.push_back(c.second);
 219     }
 220     // add lemma enforcing introduced constants to be distinct
 221     if (consts.size() > 1)
 222     {
 223       Node distinct_const = nm->mkNode(kind::DISTINCT, consts);
 224       Trace("sort-inference-rewrite")
 225           << "Add the constant distinctness lemma: " << std::endl;
 226       Trace("sort-inference-rewrite") << "  " << distinct_const << std::endl;
 227       new_asserts.push_back(distinct_const);
 228     }
 229   }
 230
 231   // enforce constraints based on monotonicity
 232   Trace("sort-inference-proc") << "Enforce monotonicity..." << std::endl;
 233
 234   for (const std::pair<const TypeNode, std::vector<int> >& tss :
 235        d_type_sub_sorts)
 236   {
 237     int nmonSort = -1;
 238     unsigned nsorts = tss.second.size();
 239     for (unsigned i = 0; i < nsorts; i++)
 240     {
 241       if (d_non_monotonic_sorts.find(tss.second[i])
 242           != d_non_monotonic_sorts.end())
 243       {
 244         nmonSort = tss.second[i];
 245         break;
 246       }
 247     }
 248     if (nmonSort != -1)
 249     {
 250       std::vector<Node> injections;
 251       TypeNode base_tn = getOrCreateTypeForId(nmonSort, tss.first);
 252       for (unsigned i = 0; i < nsorts; i++)
 253       {
 254         if (tss.second[i] != nmonSort)
 255         {
 256           TypeNode new_tn = getOrCreateTypeForId(tss.second[i], tss.first);
 257           // make injection to nmonSort
 258           Node a1 = mkInjection(new_tn, base_tn);
 259           injections.push_back(a1);
 260           if (d_non_monotonic_sorts.find(tss.second[i])
 261               != d_non_monotonic_sorts.end())
 262           {
 263             // also must make injection from nmonSort to this
 264             Node a2 = mkInjection(base_tn, new_tn);
 265             injections.push_back(a2);
 266           }
 267         }
 268       }
 269       if (Trace.isOn("sort-inference-rewrite"))
 270       {
 271         Trace("sort-inference-rewrite")
 272             << "Add the following injections for " << tss.first
 273             << " to ensure consistency wrt non-monotonic sorts : " << std::endl;
 274         for (const Node& i : injections)
 275         {
 276           Trace("sort-inference-rewrite") << "   " << i << std::endl;
 277         }
 278       }
 279       new_asserts.insert(
 280           new_asserts.end(), injections.begin(), injections.end());
 281     }
 282   }
 283   Trace("sort-inference-proc") << "...done" << std::endl;
 284   // no sub-sort information is stored
 285   reset();
 286   Trace("sort-inference-debug") << "Finished sort inference" << std::endl;
 287 }
 288
 289 void SortInference::computeMonotonicity(const std::vector<Node>& assertions)
 290 {
 291   std::map<Node, std::map<int, bool> > visitedmt;
 292   Trace("sort-inference-proc")
 293       << "Calculating monotonicty for types..." << std::endl;
 294   for (const Node& a : assertions)
 295   {
 296     Trace("sort-inference-debug")
 297         << "Process type monotonicity for " << a << std::endl;
 298     std::map<Node, Node> var_bound;
 299     processMonotonic(a, true, true, var_bound, visitedmt, true);
 300   }
 301   Trace("sort-inference-proc") << "...done" << std::endl;
 302 }
 303
 304 void SortInference::setEqual( int t1, int t2 ){
 305   if( t1!=t2 ){
 306     int rt1 = d_type_union_find.getRepresentative( t1 );
 307     int rt2 = d_type_union_find.getRepresentative( t2 );
 308     if( rt1!=rt2 ){
 309       Trace("sort-inference-debug") << "Set equal : ";
 310       printSort( "sort-inference-debug", rt1 );
 311       Trace("sort-inference-debug") << " ";
 312       printSort( "sort-inference-debug", rt2 );
 313       Trace("sort-inference-debug") << std::endl;
 314       /*
 315       d_type_eq_class[rt1].insert( d_type_eq_class[rt1].end(), d_type_eq_class[rt2].begin(), d_type_eq_class[rt2].end() );
 316       d_type_eq_class[rt2].clear();
 317       Trace("sort-inference-debug") << "EqClass : { ";
 318       for( int i=0; i<(int)d_type_eq_class[rt1].size(); i++ ){
 319         Trace("sort-inference-debug") << d_type_eq_class[rt1][i] << ", ";
 320       }
 321       Trace("sort-inference-debug") << "}" << std::endl;
 322       */
 323       if( rt2>rt1 ){
 324         //swap
 325         int swap = rt1;
 326         rt1 = rt2;
 327         rt2 = swap;
 328       }
 329       std::map< int, TypeNode >::iterator it1 = d_type_types.find( rt1 );
 330       if( it1!=d_type_types.end() ){
 331         if( d_type_types.find( rt2 )==d_type_types.end() ){
 332           d_type_types[rt2] = it1->second;
 333           d_type_types.erase( rt1 );
 334         }else{
 335           Trace("sort-inference-debug") << "...fail : associated with types " << d_type_types[rt1] << " and " << d_type_types[rt2] << std::endl;
 336           return;
 337         }
 338       }
 339       d_type_union_find.d_eqc[rt1] = rt2;
 340     }
 341   }
 342 }
 343
 344 int SortInference::getIdForType( TypeNode tn ){
 345   //register the return type
 346   std::map< TypeNode, int >::iterator it = d_id_for_types.find( tn );
 347   if( it==d_id_for_types.end() ){
 348     int sc = d_sortCount;
 349     d_type_types[d_sortCount] = tn;
 350     d_id_for_types[tn] = d_sortCount;
 351     d_sortCount++;
 352     return sc;
 353   }else{
 354     return it->second;
 355   }
 356 }
 357
 358 int SortInference::process( Node n, std::map< Node, Node >& var_bound, std::map< Node, int >& visited ){
 359   std::map< Node, int >::iterator itv = visited.find( n );
 360   if( itv!=visited.end() ){
 361     return itv->second;
 362   }else{
 363     //add to variable bindings
 364     bool use_new_visited = false;
 365     std::map< Node, int > new_visited;
 366     if( n.getKind()==kind::FORALL || n.getKind()==kind::EXISTS ){
 367       if( d_var_types.find( n )!=d_var_types.end() ){
 368         return getIdForType( n.getType() );
 369       }else{
 370         //apply sort inference to quantified variables
 371         for( size_t i=0; i<n[0].getNumChildren(); i++ ){
 372           TypeNode nitn = n[0][i].getType();
 373           if( !nitn.isSort() )
 374           {
 375             // If the variable is of an interpreted sort, we assume the
 376             // the sort of the variable will stay the same sort.
 377             d_var_types[n][n[0][i]] = getIdForType( nitn );
 378           }
 379           else
 380           {
 381             // If it is of an uninterpreted sort, infer subsorts.
 382             d_var_types[n][n[0][i]] = d_sortCount;
 383             d_sortCount++;
 384           }
 385           var_bound[ n[0][i] ] = n;
 386         }
 387       }
 388       use_new_visited = true;
 389     }
 390
 391     //process children
 392     std::vector< Node > children;
 393     std::vector< int > child_types;
 394     for( size_t i=0; i<n.getNumChildren(); i++ ){
 395       bool processChild = true;
 396       if( n.getKind()==kind::FORALL || n.getKind()==kind::EXISTS ){
 397         processChild = options::userPatternsQuant()==theory::quantifiers::USER_PAT_MODE_IGNORE ? i==1 : i>=1;
 398       }
 399       if( processChild ){
 400         children.push_back( n[i] );
 401         child_types.push_back( process( n[i], var_bound, use_new_visited ? new_visited : visited ) );
 402       }
 403     }
 404
 405     //remove from variable bindings
 406     if( n.getKind()==kind::FORALL || n.getKind()==kind::EXISTS ){
 407       //erase from variable bound
 408       for( size_t i=0; i<n[0].getNumChildren(); i++ ){
 409         var_bound.erase( n[0][i] );
 410       }
 411     }
 412     Trace("sort-inference-debug") << "...Process " << n << std::endl;
 413
 414     int retType;
 415     if( n.getKind()==kind::EQUAL && !n[0].getType().isBoolean() ){
 416       Trace("sort-inference-debug") << "For equality " << n << ", set equal types from : " << n[0].getType() << " " << n[1].getType() << std::endl;
 417       //if original types are mixed (e.g. Int/Real), don't commit type equality in either direction
 418       if( n[0].getType()!=n[1].getType() ){
 419         //for now, assume the original types
 420         for( unsigned i=0; i<2; i++ ){
 421           int ct = getIdForType( n[i].getType() );
 422           setEqual( child_types[i], ct );
 423         }
 424       }else{
 425         //we only require that the left and right hand side must be equal
 426         setEqual( child_types[0], child_types[1] );
 427       }
 428       d_equality_types[n] = child_types[0];
 429       retType = getIdForType( n.getType() );
 430     }else if( n.getKind()==kind::APPLY_UF ){
 431       Node op = n.getOperator();
 432       TypeNode tn_op = op.getType();
 433       if( d_op_return_types.find( op )==d_op_return_types.end() ){
 434         if( n.getType().isBoolean() ){
 435           //use booleans
 436           d_op_return_types[op] = getIdForType( n.getType() );
 437         }else{
 438           //assign arbitrary sort for return type
 439           d_op_return_types[op] = d_sortCount;
 440           d_sortCount++;
 441         }
 442         // d_type_eq_class[d_sortCount].push_back( op );
 443         // assign arbitrary sort for argument types
 444         for( size_t i=0; i<n.getNumChildren(); i++ ){
 445           d_op_arg_types[op].push_back(d_sortCount);
 446           d_sortCount++;
 447         }
 448       }
 449       for( size_t i=0; i<n.getNumChildren(); i++ ){
 450         //the argument of the operator must match the return type of the subterm
 451         if( n[i].getType()!=tn_op[i] ){
 452           //if type mismatch, assume original types
 453           Trace("sort-inference-debug") << "Argument " << i << " of " << op << " " << n[i] << " has type " << n[i].getType();
 454           Trace("sort-inference-debug") << ", while operator arg has type " << tn_op[i] << std::endl;
 455           int ct1 = getIdForType( n[i].getType() );
 456           setEqual( child_types[i], ct1 );
 457           int ct2 = getIdForType( tn_op[i] );
 458           setEqual( d_op_arg_types[op][i], ct2 );
 459         }else{
 460           setEqual( child_types[i], d_op_arg_types[op][i] );
 461         }
 462       }
 463       //return type is the return type
 464       retType = d_op_return_types[op];
 465     }else{
 466       std::map< Node, Node >::iterator it = var_bound.find( n );
 467       if( it!=var_bound.end() ){
 468         Trace("sort-inference-debug") << n << " is a bound variable." << std::endl;
 469         //the return type was specified while binding
 470         retType = d_var_types[it->second][n];
 471       }else if( n.getKind() == kind::VARIABLE || n.getKind()==kind::SKOLEM ){
 472         Trace("sort-inference-debug") << n << " is a variable." << std::endl;
 473         if( d_op_return_types.find( n )==d_op_return_types.end() ){
 474           //assign arbitrary sort
 475           d_op_return_types[n] = d_sortCount;
 476           d_sortCount++;
 477           // d_type_eq_class[d_sortCount].push_back( n );
 478         }
 479         retType = d_op_return_types[n];
 480       }else if( n.isConst() ){
 481         Trace("sort-inference-debug") << n << " is a constant." << std::endl;
 482         //can be any type we want
 483         retType = d_sortCount;
 484         d_sortCount++;
 485       }else{
 486         Trace("sort-inference-debug") << n << " is a interpreted symbol." << std::endl;
 487         //it is an interpreted term
 488         for( size_t i=0; i<children.size(); i++ ){
 489           Trace("sort-inference-debug") << children[i] << " forced to have " << children[i].getType() << std::endl;
 490           //must enforce the actual type of the operator on the children
 491           int ct = getIdForType( children[i].getType() );
 492           setEqual( child_types[i], ct );
 493         }
 494         //return type must be the actual return type
 495         retType = getIdForType( n.getType() );
 496       }
 497     }
 498     Trace("sort-inference-debug") << "...Type( " << n << " ) = ";
 499     printSort("sort-inference-debug", retType );
 500     Trace("sort-inference-debug") << std::endl;
 501     visited[n] = retType;
 502     return retType;
 503   }
 504 }
 505
 506 void SortInference::processMonotonic( Node n, bool pol, bool hasPol, std::map< Node, Node >& var_bound, std::map< Node, std::map< int, bool > >& visited, bool typeMode ) {
 507   int pindex = hasPol ? ( pol ? 1 : -1 ) : 0;
 508   if( visited[n].find( pindex )==visited[n].end() ){
 509     visited[n][pindex] = true;
 510     Trace("sort-inference-debug") << "...Process monotonic " << pol << " " << hasPol << " " << n << std::endl;
 511     if( n.getKind()==kind::FORALL ){
 512       //only consider variables universally if it is possible this quantified formula is asserted positively
 513       if( !hasPol || pol ){
 514         for( unsigned i=0; i<n[0].getNumChildren(); i++ ){
 515           var_bound[n[0][i]] = n;
 516         }
 517       }
 518       processMonotonic( n[1], pol, hasPol, var_bound, visited, typeMode );
 519       if( !hasPol || pol ){
 520         for( unsigned i=0; i<n[0].getNumChildren(); i++ ){
 521           var_bound.erase( n[0][i] );
 522         }
 523       }
 524       return;
 525     }else if( n.getKind()==kind::EQUAL ){
 526       if( !hasPol || pol ){
 527         for( unsigned i=0; i<2; i++ ){
 528           if( var_bound.find( n[i] )!=var_bound.end() ){
 529             if( !typeMode ){
 530               int sid = getSortId( var_bound[n[i]], n[i] );
 531               d_non_monotonic_sorts[sid] = true;
 532             }else{
 533               d_non_monotonic_sorts_orig[n[i].getType()] = true;
 534             }
 535             break;
 536           }
 537         }
 538       }
 539     }
 540     for( unsigned i=0; i<n.getNumChildren(); i++ ){
 541       bool npol;
 542       bool nhasPol;
 543       theory::QuantPhaseReq::getPolarity( n, i, hasPol, pol, nhasPol, npol );
 544       processMonotonic( n[i], npol, nhasPol, var_bound, visited, typeMode );
 545     }
 546   }
 547 }
 548
 549
 550 TypeNode SortInference::getOrCreateTypeForId( int t, TypeNode pref ){
 551   int rt = d_type_union_find.getRepresentative( t );
 552   if( d_type_types.find( rt )!=d_type_types.end() ){
 553     return d_type_types[rt];
 554   }else{
 555     TypeNode retType;
 556     // See if we can assign pref. This is an optimization for reusing an
 557     // uninterpreted sort as the first subsort, so that fewer symbols needed
 558     // to be rewritten in the sort-inferred signature. Notice we only assign
 559     // pref here if it is an uninterpreted sort.
 560     if (!pref.isNull() && d_id_for_types.find(pref) == d_id_for_types.end()
 561         && pref.isSort())
 562     {
 563       retType = pref;
 564     }else{
 565       //must create new type
 566       std::stringstream ss;
 567       ss << "it_" << t << "_" << pref;
 568       retType = NodeManager::currentNM()->mkSort( ss.str() );
 569     }
 570     Trace("sort-inference") << "-> Make type " << retType << " to correspond to ";
 571     printSort("sort-inference", t );
 572     Trace("sort-inference") << std::endl;
 573     d_id_for_types[ retType ] = rt;
 574     d_type_types[ rt ] = retType;
 575     return retType;
 576   }
 577 }
 578
 579 TypeNode SortInference::getTypeForId( int t ){
 580   int rt = d_type_union_find.getRepresentative( t );
 581   if( d_type_types.find( rt )!=d_type_types.end() ){
 582     return d_type_types[rt];
 583   }else{
 584     return TypeNode::null();
 585   }
 586 }
 587
 588 Node SortInference::getNewSymbol( Node old, TypeNode tn ){
 589   // if no sort was inferred for this node, return original
 590   if( tn.isNull() || tn.isComparableTo( old.getType() ) ){
 591     return old;
 592   }else if( old.isConst() ){
 593     //must make constant of type tn
 594     if( d_const_map[tn].find( old )==d_const_map[tn].end() ){
 595       std::stringstream ss;
 596       ss << "ic_" << tn << "_" << old;
 597       d_const_map[tn][ old ] = NodeManager::currentNM()->mkSkolem( ss.str(), tn, "constant created during sort inference" );  //use mkConst???
 598     }
 599     return d_const_map[tn][ old ];
 600   }else if( old.getKind()==kind::BOUND_VARIABLE ){
 601     std::stringstream ss;
 602     ss << "b_" << old;
 603     return NodeManager::currentNM()->mkBoundVar( ss.str(), tn );
 604   }else{
 605     std::stringstream ss;
 606     ss << "i_" << old;
 607     return NodeManager::currentNM()->mkSkolem( ss.str(), tn, "created during sort inference" );
 608   }
 609 }
 610
 611 Node SortInference::simplifyNode(
 612     Node n,
 613     std::map<Node, Node>& var_bound,
 614     TypeNode tnn,
 615     std::map<Node, Node>& model_replace_f,
 616     std::map<Node, std::map<TypeNode, Node> >& visited)
 617 {
 618   std::map< TypeNode, Node >::iterator itv = visited[n].find( tnn );
 619   if( itv!=visited[n].end() ){
 620     return itv->second;
 621   }else{
 622     Trace("sort-inference-debug2") << "Simplify " << n << ", type context=" << tnn << std::endl;
 623     std::vector< Node > children;
 624     std::map< Node, std::map< TypeNode, Node > > new_visited;
 625     bool use_new_visited = false;
 626     if( n.getKind()==kind::FORALL || n.getKind()==kind::EXISTS ){
 627       //recreate based on types of variables
 628       std::vector< Node > new_children;
 629       for( size_t i=0; i<n[0].getNumChildren(); i++ ){
 630         TypeNode tn = getOrCreateTypeForId( d_var_types[n][ n[0][i] ], n[0][i].getType() );
 631         Node v = getNewSymbol( n[0][i], tn );
 632         Trace("sort-inference-debug2") << "Map variable " << n[0][i] << " to " << v << std::endl;
 633         new_children.push_back( v );
 634         var_bound[ n[0][i] ] = v;
 635       }
 636       children.push_back( NodeManager::currentNM()->mkNode( n[0].getKind(), new_children ) );
 637       use_new_visited = true;
 638     }
 639
 640     //process children
 641     if( n.getMetaKind() == kind::metakind::PARAMETERIZED ){
 642       children.push_back( n.getOperator() );
 643     }
 644     Node op;
 645     if( n.hasOperator() ){
 646       op = n.getOperator();
 647     }
 648     bool childChanged = false;
 649     TypeNode tnnc;
 650     for( size_t i=0; i<n.getNumChildren(); i++ ){
 651       bool processChild = true;
 652       if( n.getKind()==kind::FORALL || n.getKind()==kind::EXISTS ){
 653         processChild = options::userPatternsQuant()==theory::quantifiers::USER_PAT_MODE_IGNORE ? i==1 : i>=1;
 654       }
 655       if( processChild ){
 656         if( n.getKind()==kind::APPLY_UF ){
 657           Assert( d_op_arg_types.find( op )!=d_op_arg_types.end() );
 658           tnnc = getOrCreateTypeForId( d_op_arg_types[op][i], n[i].getType() );
 659           Assert( !tnnc.isNull() );
 660         }else if( n.getKind()==kind::EQUAL && i==0 ){
 661           Assert( d_equality_types.find( n )!=d_equality_types.end() );
 662           tnnc = getOrCreateTypeForId( d_equality_types[n], n[0].getType() );
 663           Assert( !tnnc.isNull() );
 664         }
 665         Node nc = simplifyNode(n[i],
 666                                var_bound,
 667                                tnnc,
 668                                model_replace_f,
 669                                use_new_visited ? new_visited : visited);
 670         Trace("sort-inference-debug2") << "Simplify " << i << " " << n[i] << " returned " << nc << std::endl;
 671         children.push_back( nc );
 672         childChanged = childChanged || nc!=n[i];
 673       }
 674     }
 675
 676     //remove from variable bindings
 677     Node ret;
 678     if( n.getKind()==kind::FORALL || n.getKind()==kind::EXISTS ){
 679       //erase from variable bound
 680       for( size_t i=0; i<n[0].getNumChildren(); i++ ){
 681         Trace("sort-inference-debug2") << "Remove bound for " << n[0][i] << std::endl;
 682         var_bound.erase( n[0][i] );
 683       }
 684       ret = NodeManager::currentNM()->mkNode( n.getKind(), children );
 685     }else if( n.getKind()==kind::EQUAL ){
 686       TypeNode tn1 = children[0].getType();
 687       TypeNode tn2 = children[1].getType();
 688       if( !tn1.isSubtypeOf( tn2 ) && !tn2.isSubtypeOf( tn1 ) ){
 689         Trace("sort-inference-warn") << "Sort inference created bad equality: " << children[0] << " = " << children[1] << std::endl;
 690         Trace("sort-inference-warn") << "  Types : " << children[0].getType() << " " << children[1].getType() << std::endl;
 691         Assert( false );
 692       }
 693       ret = NodeManager::currentNM()->mkNode( kind::EQUAL, children );
 694     }else if( n.getKind()==kind::APPLY_UF ){
 695       if( d_symbol_map.find( op )==d_symbol_map.end() ){
 696         //make the new operator if necessary
 697         bool opChanged = false;
 698         std::vector< TypeNode > argTypes;
 699         for( size_t i=0; i<n.getNumChildren(); i++ ){
 700           TypeNode tn = getOrCreateTypeForId( d_op_arg_types[op][i], n[i].getType() );
 701           argTypes.push_back( tn );
 702           if( tn!=n[i].getType() ){
 703             opChanged = true;
 704           }
 705         }
 706         TypeNode retType = getOrCreateTypeForId( d_op_return_types[op], n.getType() );
 707         if( retType!=n.getType() ){
 708           opChanged = true;
 709         }
 710         if( opChanged ){
 711           std::stringstream ss;
 712           ss << "io_" << op;
 713           TypeNode typ = NodeManager::currentNM()->mkFunctionType( argTypes, retType );
 714           d_symbol_map[op] = NodeManager::currentNM()->mkSkolem( ss.str(), typ, "op created during sort inference" );
 715           Trace("setp-model") << "Function " << op << " is replaced with " << d_symbol_map[op] << std::endl;
 716           model_replace_f[op] = d_symbol_map[op];
 717         }else{
 718           d_symbol_map[op] = op;
 719         }
 720       }
 721       children[0] = d_symbol_map[op];
 722       // make sure all children have been given proper types
 723       for (size_t i = 0, size = n.getNumChildren(); i < size; i++)
 724       {
 725         TypeNode tn = children[i+1].getType();
 726         TypeNode tna = getTypeForId( d_op_arg_types[op][i] );
 727         if (!tn.isSubtypeOf(tna))
 728         {
 729           Trace("sort-inference-warn") << "Sort inference created bad child: " << n << " " << n[i] << " " << tn << " " << tna << std::endl;
 730           Assert( false );
 731         }
 732       }
 733       ret = NodeManager::currentNM()->mkNode( kind::APPLY_UF, children );
 734     }else{
 735       std::map< Node, Node >::iterator it = var_bound.find( n );
 736       if( it!=var_bound.end() ){
 737         ret = it->second;
 738       }else if( n.getKind() == kind::VARIABLE || n.getKind() == kind::SKOLEM ){
 739         if( d_symbol_map.find( n )==d_symbol_map.end() ){
 740           TypeNode tn = getOrCreateTypeForId( d_op_return_types[n], n.getType() );
 741           d_symbol_map[n] = getNewSymbol( n, tn );
 742         }
 743         ret = d_symbol_map[n];
 744       }else if( n.isConst() ){
 745         //type is determined by context
 746         ret = getNewSymbol( n, tnn );
 747       }else if( childChanged ){
 748         ret = NodeManager::currentNM()->mkNode( n.getKind(), children );
 749       }else{
 750         ret = n;
 751       }
 752     }
 753     visited[n][tnn] = ret;
 754     return ret;
 755   }
 756 }
 757
 758 Node SortInference::mkInjection( TypeNode tn1, TypeNode tn2 ) {
 759   std::vector< TypeNode > tns;
 760   tns.push_back( tn1 );
 761   TypeNode typ = NodeManager::currentNM()->mkFunctionType( tns, tn2 );
 762   Node f = NodeManager::currentNM()->mkSkolem( "inj", typ, "injection for monotonicity constraint" );
 763   Trace("sort-inference") << "-> Make injection " << f << " from " << tn1 << " to " << tn2 << std::endl;
 764   Node v1 = NodeManager::currentNM()->mkBoundVar( "?x", tn1 );
 765   Node v2 = NodeManager::currentNM()->mkBoundVar( "?y", tn1 );
 766   Node ret = NodeManager::currentNM()->mkNode( kind::FORALL,
 767                NodeManager::currentNM()->mkNode( kind::BOUND_VAR_LIST, v1, v2 ),
 768                NodeManager::currentNM()->mkNode( kind::OR,
 769                  NodeManager::currentNM()->mkNode( kind::APPLY_UF, f, v1 ).eqNode( NodeManager::currentNM()->mkNode( kind::APPLY_UF, f, v2 ) ).negate(),
 770                  v1.eqNode( v2 ) ) );
 771   ret = theory::Rewriter::rewrite( ret );
 772   return ret;
 773 }
 774
 775 int SortInference::getSortId( Node n ) {
 776   Node op = n.getKind()==kind::APPLY_UF ? n.getOperator() : n;
 777   if( d_op_return_types.find( op )!=d_op_return_types.end() ){
 778     return d_type_union_find.getRepresentative( d_op_return_types[op] );
 779   }else{
 780     return 0;
 781   }
 782 }
 783
 784 int SortInference::getSortId( Node f, Node v ) {
 785   if( d_var_types.find( f )!=d_var_types.end() ){
 786     return d_type_union_find.getRepresentative( d_var_types[f][v] );
 787   }else{
 788     return 0;
 789   }
 790 }
 791
 792 void SortInference::setSkolemVar( Node f, Node v, Node sk ){
 793   Trace("sort-inference-temp") << "Set skolem var for " << f << ", variable " << v << std::endl;
 794   if( isWellSortedFormula( f ) && d_var_types.find( f )==d_var_types.end() ){
 795     //calculate the sort for variables if not done so already
 796     std::map< Node, Node > var_bound;
 797     std::map< Node, int > visited;
 798     process( f, var_bound, visited );
 799   }
 800   d_op_return_types[sk] = getSortId( f, v );
 801   Trace("sort-inference-temp") << "Set skolem sort id for " << sk << " to " << d_op_return_types[sk] << std::endl;
 802 }
 803
 804 bool SortInference::isWellSortedFormula( Node n ) {
 805   if( n.getType().isBoolean() && n.getKind()!=kind::APPLY_UF ){
 806     for( unsigned i=0; i<n.getNumChildren(); i++ ){
 807       if( !isWellSortedFormula( n[i] ) ){
 808         return false;
 809       }
 810     }
 811     return true;
 812   }else{
 813     return isWellSorted( n );
 814   }
 815 }
 816
 817 bool SortInference::isWellSorted( Node n ) {
 818   if( getSortId( n )==0 ){
 819     return false;
 820   }else{
 821     if( n.getKind()==kind::APPLY_UF ){
 822       for( unsigned i=0; i<n.getNumChildren(); i++ ){
 823         int s1 = getSortId( n[i] );
 824         int s2 = d_type_union_find.getRepresentative( d_op_arg_types[ n.getOperator() ][i] );
 825         if( s1!=s2 ){
 826           return false;
 827         }
 828         if( !isWellSorted( n[i] ) ){
 829           return false;
 830         }
 831       }
 832     }
 833     return true;
 834   }
 835 }
 836
 837 void SortInference::getSortConstraints( Node n, UnionFind& uf ) {
 838   if( n.getKind()==kind::APPLY_UF ){
 839     for( unsigned i=0; i<n.getNumChildren(); i++ ){
 840       getSortConstraints( n[i], uf );
 841       uf.setEqual( getSortId( n[i] ), d_type_union_find.getRepresentative( d_op_arg_types[ n.getOperator() ][i] ) );
 842     }
 843   }
 844 }
 845
 846 bool SortInference::isMonotonic( TypeNode tn ) {
 847   Assert( tn.isSort() );
 848   return d_non_monotonic_sorts_orig.find( tn )==d_non_monotonic_sorts_orig.end();
 849 }
 850
 851 }/* CVC4 namespace */