src/theory/theory_model_builder.cpp

   1 /*********************                                                        */
   2 /*! \file theory_model_builder.cpp
   3  ** \verbatim
   4  ** Top contributors (to current version):
   5  **   Clark Barrett, Andrew Reynolds, Morgan Deters
   6  ** This file is part of the CVC4 project.
   7  ** Copyright (c) 2009-2017 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 Implementation of theory model buidler class
  13  **/
  14 #include "theory/theory_model_builder.h"
  15
  16 #include "options/quantifiers_options.h"
  17 #include "options/smt_options.h"
  18 #include "options/uf_options.h"
  19 #include "theory/theory_engine.h"
  20 #include "theory/uf/theory_uf_model.h"
  21
  22 using namespace std;
  23 using namespace CVC4::kind;
  24 using namespace CVC4::context;
  25
  26 namespace CVC4 {
  27 namespace theory {
  28
  29 TheoryEngineModelBuilder::TheoryEngineModelBuilder(TheoryEngine* te) : d_te(te)
  30 {
  31 }
  32
  33 bool TheoryEngineModelBuilder::isAssignable(TNode n)
  34 {
  35   if (n.getKind() == kind::SELECT || n.getKind() == kind::APPLY_SELECTOR_TOTAL)
  36   {
  37     // selectors are always assignable (where we guarantee that they are not
  38     // evaluatable here)
  39     if (!options::ufHo())
  40     {
  41       Assert(!n.getType().isFunction());
  42       return true;
  43     }
  44     else
  45     {
  46       // might be a function field
  47       return !n.getType().isFunction();
  48     }
  49   }
  50   else
  51   {
  52     // non-function variables, and fully applied functions
  53     if (!options::ufHo())
  54     {
  55       // no functions exist, all functions are fully applied
  56       Assert(n.getKind() != kind::HO_APPLY);
  57       Assert(!n.getType().isFunction());
  58       return n.isVar() || n.getKind() == kind::APPLY_UF;
  59     }
  60     else
  61     {
  62       // Assert( n.getKind() != kind::APPLY_UF );
  63       return (n.isVar() && !n.getType().isFunction())
  64              || n.getKind() == kind::APPLY_UF
  65              || (n.getKind() == kind::HO_APPLY
  66                  && n[0].getType().getNumChildren() == 2);
  67     }
  68   }
  69 }
  70
  71 void TheoryEngineModelBuilder::addAssignableSubterms(TNode n,
  72                                                      TheoryModel* tm,
  73                                                      NodeSet& cache)
  74 {
  75   if (n.getKind() == FORALL || n.getKind() == EXISTS)
  76   {
  77     return;
  78   }
  79   if (cache.find(n) != cache.end())
  80   {
  81     return;
  82   }
  83   if (isAssignable(n))
  84   {
  85     tm->d_equalityEngine->addTerm(n);
  86   }
  87   for (TNode::iterator child_it = n.begin(); child_it != n.end(); ++child_it)
  88   {
  89     addAssignableSubterms(*child_it, tm, cache);
  90   }
  91   cache.insert(n);
  92 }
  93
  94 void TheoryEngineModelBuilder::assignConstantRep(TheoryModel* tm,
  95                                                  Node eqc,
  96                                                  Node const_rep)
  97 {
  98   d_constantReps[eqc] = const_rep;
  99   Trace("model-builder") << "    Assign: Setting constant rep of " << eqc
 100                          << " to " << const_rep << endl;
 101   tm->d_rep_set.setTermForRepresentative(const_rep, eqc);
 102 }
 103
 104 bool TheoryEngineModelBuilder::isExcludedCdtValue(
 105     Node val,
 106     std::set<Node>* repSet,
 107     std::map<Node, Node>& assertedReps,
 108     Node eqc)
 109 {
 110   Trace("model-builder-debug")
 111       << "Is " << val << " and excluded codatatype value for " << eqc << "? "
 112       << std::endl;
 113   for (set<Node>::iterator i = repSet->begin(); i != repSet->end(); ++i)
 114   {
 115     Assert(assertedReps.find(*i) != assertedReps.end());
 116     Node rep = assertedReps[*i];
 117     Trace("model-builder-debug") << "  Rep : " << rep << std::endl;
 118     // check matching val to rep with eqc as a free variable
 119     Node eqc_m;
 120     if (isCdtValueMatch(val, rep, eqc, eqc_m))
 121     {
 122       Trace("model-builder-debug") << "  ...matches with " << eqc << " -> "
 123                                    << eqc_m << std::endl;
 124       if (eqc_m.getKind() == kind::UNINTERPRETED_CONSTANT)
 125       {
 126         Trace("model-builder-debug") << "*** " << val
 127                                      << " is excluded datatype for " << eqc
 128                                      << std::endl;
 129         return true;
 130       }
 131     }
 132   }
 133   return false;
 134 }
 135
 136 bool TheoryEngineModelBuilder::isCdtValueMatch(Node v,
 137                                                Node r,
 138                                                Node eqc,
 139                                                Node& eqc_m)
 140 {
 141   if (r == v)
 142   {
 143     return true;
 144   }
 145   else if (r == eqc)
 146   {
 147     if (eqc_m.isNull())
 148     {
 149       // only if an uninterpreted constant?
 150       eqc_m = v;
 151       return true;
 152     }
 153     else
 154     {
 155       return v == eqc_m;
 156     }
 157   }
 158   else if (v.getKind() == kind::APPLY_CONSTRUCTOR
 159            && r.getKind() == kind::APPLY_CONSTRUCTOR)
 160   {
 161     if (v.getOperator() == r.getOperator())
 162     {
 163       for (unsigned i = 0; i < v.getNumChildren(); i++)
 164       {
 165         if (!isCdtValueMatch(v[i], r[i], eqc, eqc_m))
 166         {
 167           return false;
 168         }
 169       }
 170       return true;
 171     }
 172   }
 173   return false;
 174 }
 175
 176 bool TheoryEngineModelBuilder::involvesUSort(TypeNode tn)
 177 {
 178   if (tn.isSort())
 179   {
 180     return true;
 181   }
 182   else if (tn.isArray())
 183   {
 184     return involvesUSort(tn.getArrayIndexType())
 185            || involvesUSort(tn.getArrayConstituentType());
 186   }
 187   else if (tn.isSet())
 188   {
 189     return involvesUSort(tn.getSetElementType());
 190   }
 191   else if (tn.isDatatype())
 192   {
 193     const Datatype& dt = ((DatatypeType)(tn).toType()).getDatatype();
 194     return dt.involvesUninterpretedType();
 195   }
 196   else
 197   {
 198     return false;
 199   }
 200 }
 201
 202 bool TheoryEngineModelBuilder::isExcludedUSortValue(
 203     std::map<TypeNode, unsigned>& eqc_usort_count,
 204     Node v,
 205     std::map<Node, bool>& visited)
 206 {
 207   Assert(v.isConst());
 208   if (visited.find(v) == visited.end())
 209   {
 210     visited[v] = true;
 211     TypeNode tn = v.getType();
 212     if (tn.isSort())
 213     {
 214       Trace("model-builder-debug") << "Is excluded usort value : " << v << " "
 215                                    << tn << std::endl;
 216       unsigned card = eqc_usort_count[tn];
 217       Trace("model-builder-debug") << "  Cardinality is " << card << std::endl;
 218       unsigned index =
 219           v.getConst<UninterpretedConstant>().getIndex().toUnsignedInt();
 220       Trace("model-builder-debug") << "  Index is " << index << std::endl;
 221       return index > 0 && index >= card;
 222     }
 223     for (unsigned i = 0; i < v.getNumChildren(); i++)
 224     {
 225       if (isExcludedUSortValue(eqc_usort_count, v[i], visited))
 226       {
 227         return true;
 228       }
 229     }
 230   }
 231   return false;
 232 }
 233
 234 void TheoryEngineModelBuilder::addToTypeList(
 235     TypeNode tn,
 236     std::vector<TypeNode>& type_list,
 237     std::unordered_set<TypeNode, TypeNodeHashFunction>& visiting)
 238 {
 239   if (std::find(type_list.begin(), type_list.end(), tn) == type_list.end())
 240   {
 241     if (visiting.find(tn) == visiting.end())
 242     {
 243       visiting.insert(tn);
 244       /* This must make a recursive call on all types that are subterms of
 245        * values of the current type.
 246        * Note that recursive traversal here is over enumerated expressions
 247        * (very low expression depth). */
 248       if (tn.isArray())
 249       {
 250         addToTypeList(tn.getArrayIndexType(), type_list, visiting);
 251         addToTypeList(tn.getArrayConstituentType(), type_list, visiting);
 252       }
 253       else if (tn.isSet())
 254       {
 255         addToTypeList(tn.getSetElementType(), type_list, visiting);
 256       }
 257       else if (tn.isDatatype())
 258       {
 259         const Datatype& dt = ((DatatypeType)(tn).toType()).getDatatype();
 260         for (unsigned i = 0; i < dt.getNumConstructors(); i++)
 261         {
 262           for (unsigned j = 0; j < dt[i].getNumArgs(); j++)
 263           {
 264             TypeNode ctn = TypeNode::fromType(dt[i][j].getRangeType());
 265             addToTypeList(ctn, type_list, visiting);
 266           }
 267         }
 268       }
 269       Assert(std::find(type_list.begin(), type_list.end(), tn)
 270              == type_list.end());
 271       type_list.push_back(tn);
 272     }
 273   }
 274 }
 275
 276 bool TheoryEngineModelBuilder::buildModel(Model* m)
 277 {
 278   Trace("model-builder") << "TheoryEngineModelBuilder: buildModel" << std::endl;
 279   TheoryModel* tm = (TheoryModel*)m;
 280
 281   // buildModel should only be called once per check
 282   Assert(!tm->isBuilt());
 283
 284   // Reset model
 285   tm->reset();
 286
 287   // mark as built
 288   tm->d_modelBuilt = true;
 289
 290   // Collect model info from the theories
 291   Trace("model-builder") << "TheoryEngineModelBuilder: Collect model info..."
 292                          << std::endl;
 293   d_te->collectModelInfo(tm);
 294
 295   // model-builder specific initialization
 296   if (!preProcessBuildModel(tm))
 297   {
 298     return false;
 299   }
 300
 301   // Loop through all terms and make sure that assignable sub-terms are in the
 302   // equality engine
 303   // Also, record #eqc per type (for finite model finding)
 304   std::map<TypeNode, unsigned> eqc_usort_count;
 305   eq::EqClassesIterator eqcs_i = eq::EqClassesIterator(tm->d_equalityEngine);
 306   {
 307     NodeSet cache;
 308     for (; !eqcs_i.isFinished(); ++eqcs_i)
 309     {
 310       eq::EqClassIterator eqc_i =
 311           eq::EqClassIterator((*eqcs_i), tm->d_equalityEngine);
 312       for (; !eqc_i.isFinished(); ++eqc_i)
 313       {
 314         addAssignableSubterms(*eqc_i, tm, cache);
 315       }
 316       TypeNode tn = (*eqcs_i).getType();
 317       if (tn.isSort())
 318       {
 319         if (eqc_usort_count.find(tn) == eqc_usort_count.end())
 320         {
 321           eqc_usort_count[tn] = 1;
 322         }
 323         else
 324         {
 325           eqc_usort_count[tn]++;
 326         }
 327       }
 328     }
 329   }
 330
 331   Trace("model-builder") << "Collect representatives..." << std::endl;
 332
 333   // Process all terms in the equality engine, store representatives for each EC
 334   d_constantReps.clear();
 335   std::map<Node, Node> assertedReps;
 336   TypeSet typeConstSet, typeRepSet, typeNoRepSet;
 337   TypeEnumeratorProperties tep;
 338   if (options::finiteModelFind())
 339   {
 340     tep.d_fixed_usort_card = true;
 341     for (std::map<TypeNode, unsigned>::iterator it = eqc_usort_count.begin();
 342          it != eqc_usort_count.end();
 343          ++it)
 344     {
 345       Trace("model-builder") << "Fixed bound (#eqc) for " << it->first << " : "
 346                              << it->second << std::endl;
 347       tep.d_fixed_card[it->first] = Integer(it->second);
 348     }
 349     typeConstSet.setTypeEnumeratorProperties(&tep);
 350   }
 351   // AJR: build ordered list of types that ensures that base types are
 352   // enumerated first.
 353   // (I think) this is only strictly necessary for finite model finding +
 354   // parametric types instantiated with uninterpreted sorts, but is probably
 355   // a good idea to do in general since it leads to models with smaller term
 356   // sizes.
 357   std::vector<TypeNode> type_list;
 358   eqcs_i = eq::EqClassesIterator(tm->d_equalityEngine);
 359   for (; !eqcs_i.isFinished(); ++eqcs_i)
 360   {
 361     // eqc is the equivalence class representative
 362     Node eqc = (*eqcs_i);
 363     Trace("model-builder") << "Processing EC: " << eqc << endl;
 364     Assert(tm->d_equalityEngine->getRepresentative(eqc) == eqc);
 365     TypeNode eqct = eqc.getType();
 366     Assert(assertedReps.find(eqc) == assertedReps.end());
 367     Assert(d_constantReps.find(eqc) == d_constantReps.end());
 368
 369     // Loop through terms in this EC
 370     Node rep, const_rep;
 371     eq::EqClassIterator eqc_i = eq::EqClassIterator(eqc, tm->d_equalityEngine);
 372     for (; !eqc_i.isFinished(); ++eqc_i)
 373     {
 374       Node n = *eqc_i;
 375       Trace("model-builder") << "  Processing Term: " << n << endl;
 376       // Record as rep if this node was specified as a representative
 377       if (tm->d_reps.find(n) != tm->d_reps.end())
 378       {
 379         // AJR: I believe this assertion is too strict,
 380         // e.g. datatypes may assert representative for two constructor terms
 381         // that are not in the care graph and are merged during
 382         // collectModelInfo.
 383         // Assert(rep.isNull());
 384         rep = tm->d_reps[n];
 385         Assert(!rep.isNull());
 386         Trace("model-builder") << "  Rep( " << eqc << " ) = " << rep
 387                                << std::endl;
 388       }
 389       // Record as const_rep if this node is constant
 390       if (n.isConst())
 391       {
 392         Assert(const_rep.isNull());
 393         const_rep = n;
 394         Trace("model-builder") << "  ConstRep( " << eqc << " ) = " << const_rep
 395                                << std::endl;
 396       }
 397       // model-specific processing of the term
 398       tm->addTermInternal(n);
 399     }
 400
 401     // Assign representative for this EC
 402     if (!const_rep.isNull())
 403     {
 404       // Theories should not specify a rep if there is already a constant in the
 405       // EC
 406       // AJR: I believe this assertion is too strict, eqc with asserted reps may
 407       // merge with constant eqc
 408       // Assert(rep.isNull() || rep == const_rep);
 409       assignConstantRep(tm, eqc, const_rep);
 410       typeConstSet.add(eqct.getBaseType(), const_rep);
 411     }
 412     else if (!rep.isNull())
 413     {
 414       assertedReps[eqc] = rep;
 415       typeRepSet.add(eqct.getBaseType(), eqc);
 416       std::unordered_set<TypeNode, TypeNodeHashFunction> visiting;
 417       addToTypeList(eqct.getBaseType(), type_list, visiting);
 418     }
 419     else
 420     {
 421       typeNoRepSet.add(eqct, eqc);
 422       std::unordered_set<TypeNode, TypeNodeHashFunction> visiting;
 423       addToTypeList(eqct, type_list, visiting);
 424     }
 425   }
 426
 427   // Need to ensure that each EC has a constant representative.
 428
 429   Trace("model-builder") << "Processing EC's..." << std::endl;
 430
 431   TypeSet::iterator it;
 432   vector<TypeNode>::iterator type_it;
 433   set<Node>::iterator i, i2;
 434   bool changed, unassignedAssignable, assignOne = false;
 435   set<TypeNode> evaluableSet;
 436
 437   // Double-fixed-point loop
 438   // Outer loop handles a special corner case (see code at end of loop for
 439   // details)
 440   for (;;)
 441   {
 442     // Inner fixed-point loop: we are trying to learn constant values for every
 443     // EC.  Each time through this loop, we process all of the
 444     // types by type and may learn some new EC values.  EC's in one type may
 445     // depend on EC's in another type, so we need a fixed-point loop
 446     // to ensure that we learn as many EC values as possible
 447     do
 448     {
 449       changed = false;
 450       unassignedAssignable = false;
 451       evaluableSet.clear();
 452
 453       // Iterate over all types we've seen
 454       for (type_it = type_list.begin(); type_it != type_list.end(); ++type_it)
 455       {
 456         TypeNode t = *type_it;
 457         TypeNode tb = t.getBaseType();
 458         set<Node>* noRepSet = typeNoRepSet.getSet(t);
 459
 460         // 1. Try to evaluate the EC's in this type
 461         if (noRepSet != NULL && !noRepSet->empty())
 462         {
 463           Trace("model-builder") << "  Eval phase, working on type: " << t
 464                                  << endl;
 465           bool assignable, evaluable, evaluated;
 466           d_normalizedCache.clear();
 467           for (i = noRepSet->begin(); i != noRepSet->end();)
 468           {
 469             i2 = i;
 470             ++i;
 471             assignable = false;
 472             evaluable = false;
 473             evaluated = false;
 474             Trace("model-builder-debug") << "Look at eqc : " << (*i2)
 475                                          << std::endl;
 476             eq::EqClassIterator eqc_i =
 477                 eq::EqClassIterator(*i2, tm->d_equalityEngine);
 478             for (; !eqc_i.isFinished(); ++eqc_i)
 479             {
 480               Node n = *eqc_i;
 481               Trace("model-builder-debug") << "Look at term : " << n
 482                                            << std::endl;
 483               if (isAssignable(n))
 484               {
 485                 assignable = true;
 486                 Trace("model-builder-debug") << "...assignable" << std::endl;
 487               }
 488               else
 489               {
 490                 evaluable = true;
 491                 Trace("model-builder-debug") << "...try to normalize"
 492                                              << std::endl;
 493                 Node normalized = normalize(tm, n, true);
 494                 if (normalized.isConst())
 495                 {
 496                   typeConstSet.add(tb, normalized);
 497                   assignConstantRep(tm, *i2, normalized);
 498                   Trace("model-builder") << "    Eval: Setting constant rep of "
 499                                          << (*i2) << " to " << normalized
 500                                          << endl;
 501                   changed = true;
 502                   evaluated = true;
 503                   noRepSet->erase(i2);
 504                   break;
 505                 }
 506               }
 507             }
 508             if (!evaluated)
 509             {
 510               if (evaluable)
 511               {
 512                 evaluableSet.insert(tb);
 513               }
 514               if (assignable)
 515               {
 516                 unassignedAssignable = true;
 517               }
 518             }
 519           }
 520         }
 521
 522         // 2. Normalize any non-const representative terms for this type
 523         set<Node>* repSet = typeRepSet.getSet(t);
 524         if (repSet != NULL && !repSet->empty())
 525         {
 526           Trace("model-builder")
 527               << "  Normalization phase, working on type: " << t << endl;
 528           d_normalizedCache.clear();
 529           for (i = repSet->begin(); i != repSet->end();)
 530           {
 531             Assert(assertedReps.find(*i) != assertedReps.end());
 532             Node rep = assertedReps[*i];
 533             Node normalized = normalize(tm, rep, false);
 534             Trace("model-builder") << "    Normalizing rep (" << rep
 535                                    << "), normalized to (" << normalized << ")"
 536                                    << endl;
 537             if (normalized.isConst())
 538             {
 539               changed = true;
 540               typeConstSet.add(tb, normalized);
 541               assignConstantRep(tm, *i, normalized);
 542               assertedReps.erase(*i);
 543               i2 = i;
 544               ++i;
 545               repSet->erase(i2);
 546             }
 547             else
 548             {
 549               if (normalized != rep)
 550               {
 551                 assertedReps[*i] = normalized;
 552                 changed = true;
 553               }
 554               ++i;
 555             }
 556           }
 557         }
 558       }
 559     } while (changed);
 560
 561     if (!unassignedAssignable)
 562     {
 563       break;
 564     }
 565
 566     // 3. Assign unassigned assignable EC's using type enumeration - assign a
 567     // value *different* from all other EC's if the type is infinite
 568     // Assign first value from type enumerator otherwise - for finite types, we
 569     // rely on polite framework to ensure that EC's that have to be
 570     // different are different.
 571
 572     // Only make assignments on a type if:
 573     // 1. there are no terms that share the same base type with un-normalized
 574     // representatives
 575     // 2. there are no terms that share teh same base type that are unevaluated
 576     // evaluable terms
 577     // Alternatively, if 2 or 3 don't hold but we are in a special
 578     // deadlock-breaking mode where assignOne is true, go ahead and make one
 579     // assignment
 580     changed = false;
 581     // must iterate over the ordered type list to ensure that we do not
 582     // enumerate values with subterms
 583     //  having types that we are currently enumerating (when possible)
 584     //  for example, this ensures we enumerate uninterpreted sort U before (List
 585     //  of U) and (Array U U)
 586     //  however, it does not break cyclic type dependencies for mutually
 587     //  recursive datatypes, but this is handled
 588     //  by recording all subterms of enumerated values in TypeSet::addSubTerms.
 589     for (type_it = type_list.begin(); type_it != type_list.end(); ++type_it)
 590     {
 591       TypeNode t = *type_it;
 592       // continue if there are no more equivalence classes of this type to
 593       // assign
 594       std::set<Node>* noRepSetPtr = typeNoRepSet.getSet(t);
 595       if (noRepSetPtr == NULL)
 596       {
 597         continue;
 598       }
 599       set<Node>& noRepSet = *noRepSetPtr;
 600       if (noRepSet.empty())
 601       {
 602         continue;
 603       }
 604
 605       // get properties of this type
 606       bool isCorecursive = false;
 607       if (t.isDatatype())
 608       {
 609         const Datatype& dt = ((DatatypeType)(t).toType()).getDatatype();
 610         isCorecursive =
 611             dt.isCodatatype() && (!dt.isFinite(t.toType())
 612                                   || dt.isRecursiveSingleton(t.toType()));
 613       }
 614 #ifdef CVC4_ASSERTIONS
 615       bool isUSortFiniteRestricted = false;
 616       if (options::finiteModelFind())
 617       {
 618         isUSortFiniteRestricted = !t.isSort() && involvesUSort(t);
 619       }
 620 #endif
 621
 622       set<Node>* repSet = typeRepSet.getSet(t);
 623       TypeNode tb = t.getBaseType();
 624       if (!assignOne)
 625       {
 626         set<Node>* repSet = typeRepSet.getSet(tb);
 627         if (repSet != NULL && !repSet->empty())
 628         {
 629           continue;
 630         }
 631         if (evaluableSet.find(tb) != evaluableSet.end())
 632         {
 633           continue;
 634         }
 635       }
 636       Trace("model-builder") << "  Assign phase, working on type: " << t
 637                              << endl;
 638       bool assignable, evaluable CVC4_UNUSED;
 639       for (i = noRepSet.begin(); i != noRepSet.end();)
 640       {
 641         i2 = i;
 642         ++i;
 643         eq::EqClassIterator eqc_i =
 644             eq::EqClassIterator(*i2, tm->d_equalityEngine);
 645         assignable = false;
 646         evaluable = false;
 647         for (; !eqc_i.isFinished(); ++eqc_i)
 648         {
 649           Node n = *eqc_i;
 650           if (isAssignable(n))
 651           {
 652             assignable = true;
 653           }
 654           else
 655           {
 656             evaluable = true;
 657           }
 658         }
 659         Trace("model-builder-debug")
 660             << "    eqc " << *i2 << " is assignable=" << assignable
 661             << ", evaluable=" << evaluable << std::endl;
 662         if (assignable)
 663         {
 664           Assert(!evaluable || assignOne);
 665           Assert(!t.isBoolean() || (*i2).getKind() == kind::APPLY_UF);
 666           Node n;
 667           if (t.getCardinality().isInfinite())
 668           {
 669             // if (!t.isInterpretedFinite()) {
 670             bool success;
 671             do
 672             {
 673               Trace("model-builder-debug") << "Enumerate term of type " << t
 674                                            << std::endl;
 675               n = typeConstSet.nextTypeEnum(t, true);
 676               //--- AJR: this code checks whether n is a legal value
 677               Assert(!n.isNull());
 678               success = true;
 679               Trace("model-builder-debug") << "Check if excluded : " << n
 680                                            << std::endl;
 681 #ifdef CVC4_ASSERTIONS
 682               if (isUSortFiniteRestricted)
 683               {
 684                 // must not involve uninterpreted constants beyond cardinality
 685                 // bound (which assumed to coincide with #eqc)
 686                 // this is just an assertion now, since TypeEnumeratorProperties
 687                 // should ensure that only legal values are enumerated wrt this
 688                 // constraint.
 689                 std::map<Node, bool> visited;
 690                 success = !isExcludedUSortValue(eqc_usort_count, n, visited);
 691                 if (!success)
 692                 {
 693                   Trace("model-builder")
 694                       << "Excluded value for " << t << " : " << n
 695                       << " due to out of range uninterpreted constant."
 696                       << std::endl;
 697                 }
 698                 Assert(success);
 699               }
 700 #endif
 701               if (success && isCorecursive)
 702               {
 703                 if (repSet != NULL && !repSet->empty())
 704                 {
 705                   // in the case of codatatypes, check if it is in the set of
 706                   // values that we cannot assign
 707                   success = !isExcludedCdtValue(n, repSet, assertedReps, *i2);
 708                   if (!success)
 709                   {
 710                     Trace("model-builder")
 711                         << "Excluded value : " << n
 712                         << " due to alpha-equivalent codatatype expression."
 713                         << std::endl;
 714                   }
 715                 }
 716               }
 717               //---
 718             } while (!success);
 719           }
 720           else
 721           {
 722             TypeEnumerator te(t);
 723             n = *te;
 724           }
 725           Assert(!n.isNull());
 726           assignConstantRep(tm, *i2, n);
 727           changed = true;
 728           noRepSet.erase(i2);
 729           if (assignOne)
 730           {
 731             assignOne = false;
 732             break;
 733           }
 734         }
 735       }
 736     }
 737
 738     // Corner case - I'm not sure this can even happen - but it's theoretically
 739     // possible to have a cyclical dependency
 740     // in EC assignment/evaluation, e.g. EC1 = {a, b + 1}; EC2 = {b, a - 1}.  In
 741     // this case, neither one will get assigned because we are waiting
 742     // to be able to evaluate.  But we will never be able to evaluate because
 743     // the variables that need to be assigned are in
 744     // these same EC's.  In this case, repeat the whole fixed-point computation
 745     // with the difference that the first EC
 746     // that has both assignable and evaluable expressions will get assigned.
 747     if (!changed)
 748     {
 749       Assert(!assignOne);  // check for infinite loop!
 750       assignOne = true;
 751     }
 752   }
 753
 754 #ifdef CVC4_ASSERTIONS
 755   // Assert that all representatives have been converted to constants
 756   for (it = typeRepSet.begin(); it != typeRepSet.end(); ++it)
 757   {
 758     set<Node>& repSet = TypeSet::getSet(it);
 759     if (!repSet.empty())
 760     {
 761       Trace("model-builder") << "***Non-empty repSet, size = " << repSet.size()
 762                              << ", first = " << *(repSet.begin()) << endl;
 763       Assert(false);
 764     }
 765   }
 766 #endif /* CVC4_ASSERTIONS */
 767
 768   Trace("model-builder") << "Copy representatives to model..." << std::endl;
 769   tm->d_reps.clear();
 770   std::map<Node, Node>::iterator itMap;
 771   for (itMap = d_constantReps.begin(); itMap != d_constantReps.end(); ++itMap)
 772   {
 773     tm->d_reps[itMap->first] = itMap->second;
 774     tm->d_rep_set.add(itMap->second.getType(), itMap->second);
 775   }
 776
 777   Trace("model-builder") << "Make sure ECs have reps..." << std::endl;
 778   // Make sure every EC has a rep
 779   for (itMap = assertedReps.begin(); itMap != assertedReps.end(); ++itMap)
 780   {
 781     tm->d_reps[itMap->first] = itMap->second;
 782     tm->d_rep_set.add(itMap->second.getType(), itMap->second);
 783   }
 784   for (it = typeNoRepSet.begin(); it != typeNoRepSet.end(); ++it)
 785   {
 786     set<Node>& noRepSet = TypeSet::getSet(it);
 787     set<Node>::iterator i;
 788     for (i = noRepSet.begin(); i != noRepSet.end(); ++i)
 789     {
 790       tm->d_reps[*i] = *i;
 791       tm->d_rep_set.add((*i).getType(), *i);
 792     }
 793   }
 794
 795   // modelBuilder-specific initialization
 796   if (!processBuildModel(tm))
 797   {
 798     return false;
 799   }
 800   else
 801   {
 802     return true;
 803   }
 804 }
 805
 806 void TheoryEngineModelBuilder::debugCheckModel(Model* m)
 807 {
 808   TheoryModel* tm = (TheoryModel*)m;
 809 #ifdef CVC4_ASSERTIONS
 810   Assert(tm->isBuilt());
 811   eq::EqClassesIterator eqcs_i = eq::EqClassesIterator(tm->d_equalityEngine);
 812   std::map<Node, Node>::iterator itMap;
 813   // Check that every term evaluates to its representative in the model
 814   for (eqcs_i = eq::EqClassesIterator(tm->d_equalityEngine);
 815        !eqcs_i.isFinished();
 816        ++eqcs_i)
 817   {
 818     // eqc is the equivalence class representative
 819     Node eqc = (*eqcs_i);
 820     // get the representative
 821     Node rep = tm->getRepresentative(eqc);
 822     if (!rep.isConst() && eqc.getType().isBoolean())
 823     {
 824       // if Boolean, it does not necessarily have a constant representative, use
 825       // get value instead
 826       rep = tm->getValue(eqc);
 827       Assert(rep.isConst());
 828     }
 829     eq::EqClassIterator eqc_i = eq::EqClassIterator(eqc, tm->d_equalityEngine);
 830     for (; !eqc_i.isFinished(); ++eqc_i)
 831     {
 832       Node n = *eqc_i;
 833       static int repCheckInstance = 0;
 834       ++repCheckInstance;
 835
 836       // non-linear mult is not necessarily accurate wrt getValue
 837       if (n.getKind() != kind::NONLINEAR_MULT)
 838       {
 839         Debug("check-model::rep-checking") << "( " << repCheckInstance << ") "
 840                                            << "n: " << n << endl
 841                                            << "getValue(n): " << tm->getValue(n)
 842                                            << endl
 843                                            << "rep: " << rep << endl;
 844         Assert(tm->getValue(*eqc_i) == rep,
 845                "run with -d check-model::rep-checking for details");
 846       }
 847     }
 848   }
 849 #endif /* CVC4_ASSERTIONS */
 850
 851   // builder-specific debugging
 852   debugModel(tm);
 853 }
 854
 855 Node TheoryEngineModelBuilder::normalize(TheoryModel* m, TNode r, bool evalOnly)
 856 {
 857   std::map<Node, Node>::iterator itMap = d_constantReps.find(r);
 858   if (itMap != d_constantReps.end())
 859   {
 860     return (*itMap).second;
 861   }
 862   NodeMap::iterator it = d_normalizedCache.find(r);
 863   if (it != d_normalizedCache.end())
 864   {
 865     return (*it).second;
 866   }
 867   Trace("model-builder-debug") << "do normalize on " << r << std::endl;
 868   Node retNode = r;
 869   if (r.getNumChildren() > 0)
 870   {
 871     std::vector<Node> children;
 872     if (r.getMetaKind() == kind::metakind::PARAMETERIZED)
 873     {
 874       children.push_back(r.getOperator());
 875     }
 876     bool childrenConst = true;
 877     for (size_t i = 0; i < r.getNumChildren(); ++i)
 878     {
 879       Node ri = r[i];
 880       bool recurse = true;
 881       if (!ri.isConst())
 882       {
 883         if (m->d_equalityEngine->hasTerm(ri))
 884         {
 885           itMap =
 886               d_constantReps.find(m->d_equalityEngine->getRepresentative(ri));
 887           if (itMap != d_constantReps.end())
 888           {
 889             ri = (*itMap).second;
 890             recurse = false;
 891           }
 892           else if (!evalOnly)
 893           {
 894             recurse = false;
 895           }
 896         }
 897         if (recurse)
 898         {
 899           ri = normalize(m, ri, evalOnly);
 900         }
 901         if (!ri.isConst())
 902         {
 903           childrenConst = false;
 904         }
 905       }
 906       children.push_back(ri);
 907     }
 908     retNode = NodeManager::currentNM()->mkNode(r.getKind(), children);
 909     if (childrenConst)
 910     {
 911       retNode = Rewriter::rewrite(retNode);
 912       Assert(retNode.getKind() == kind::APPLY_UF
 913              || !retNode.getType().isFirstClass()
 914              || retNode.isConst());
 915     }
 916   }
 917   d_normalizedCache[r] = retNode;
 918   return retNode;
 919 }
 920
 921 bool TheoryEngineModelBuilder::preProcessBuildModel(TheoryModel* m)
 922 {
 923   return true;
 924 }
 925
 926 bool TheoryEngineModelBuilder::processBuildModel(TheoryModel* m)
 927 {
 928   assignFunctions(m);
 929   return true;
 930 }
 931
 932 void TheoryEngineModelBuilder::assignFunction(TheoryModel* m, Node f)
 933 {
 934   Assert(!options::ufHo());
 935   uf::UfModelTree ufmt(f);
 936   Node default_v;
 937   for (size_t i = 0; i < m->d_uf_terms[f].size(); i++)
 938   {
 939     Node un = m->d_uf_terms[f][i];
 940     vector<TNode> children;
 941     children.push_back(f);
 942     Trace("model-builder-debug") << "  process term : " << un << std::endl;
 943     for (size_t j = 0; j < un.getNumChildren(); ++j)
 944     {
 945       Node rc = m->getRepresentative(un[j]);
 946       Trace("model-builder-debug2") << "    get rep : " << un[j] << " returned "
 947                                     << rc << std::endl;
 948       Assert(rc.isConst());
 949       children.push_back(rc);
 950     }
 951     Node simp = NodeManager::currentNM()->mkNode(un.getKind(), children);
 952     Node v = m->getRepresentative(un);
 953     Trace("model-builder") << "  Setting (" << simp << ") to (" << v << ")"
 954                            << endl;
 955     ufmt.setValue(m, simp, v);
 956     default_v = v;
 957   }
 958   if (default_v.isNull())
 959   {
 960     // choose default value from model if none exists
 961     TypeEnumerator te(f.getType().getRangeType());
 962     default_v = (*te);
 963   }
 964   ufmt.setDefaultValue(m, default_v);
 965   bool condenseFuncValues = options::condenseFunctionValues();
 966   if (condenseFuncValues)
 967   {
 968     ufmt.simplify();
 969   }
 970   std::stringstream ss;
 971   ss << "_arg_" << f << "_";
 972   Node val = ufmt.getFunctionValue(ss.str().c_str(), condenseFuncValues);
 973   m->assignFunctionDefinition(f, val);
 974   // ufmt.debugPrint( std::cout, m );
 975 }
 976
 977 void TheoryEngineModelBuilder::assignHoFunction(TheoryModel* m, Node f)
 978 {
 979   Assert(options::ufHo());
 980   TypeNode type = f.getType();
 981   std::vector<TypeNode> argTypes = type.getArgTypes();
 982   std::vector<Node> args;
 983   std::vector<TNode> apply_args;
 984   for (unsigned i = 0; i < argTypes.size(); i++)
 985   {
 986     Node v = NodeManager::currentNM()->mkBoundVar(argTypes[i]);
 987     args.push_back(v);
 988     if (i > 0)
 989     {
 990       apply_args.push_back(v);
 991     }
 992   }
 993   // start with the base return value (currently we use the same default value
 994   // for all functions)
 995   TypeEnumerator te(type.getRangeType());
 996   Node curr = (*te);
 997   std::map<Node, std::vector<Node> >::iterator itht = m->d_ho_uf_terms.find(f);
 998   if (itht != m->d_ho_uf_terms.end())
 999   {
1000     for (size_t i = 0; i < itht->second.size(); i++)
1001     {
1002       Node hn = itht->second[i];
1003       Trace("model-builder-debug") << "    process : " << hn << std::endl;
1004       Assert(hn.getKind() == kind::HO_APPLY);
1005       Assert(m->areEqual(hn[0], f));
1006       Node hni = m->getRepresentative(hn[1]);
1007       Trace("model-builder-debug2") << "      get rep : " << hn[0]
1008                                     << " returned " << hni << std::endl;
1009       Assert(hni.isConst());
1010       Assert(hni.getType().isSubtypeOf(args[0].getType()));
1011       hni = Rewriter::rewrite(args[0].eqNode(hni));
1012       Node hnv = m->getRepresentative(hn);
1013       Trace("model-builder-debug2") << "      get rep val : " << hn
1014                                     << " returned " << hnv << std::endl;
1015       Assert(hnv.isConst());
1016       if (!apply_args.empty())
1017       {
1018         Assert(hnv.getKind() == kind::LAMBDA
1019                && hnv[0].getNumChildren() + 1 == args.size());
1020         std::vector<TNode> largs;
1021         for (unsigned j = 0; j < hnv[0].getNumChildren(); j++)
1022         {
1023           largs.push_back(hnv[0][j]);
1024         }
1025         Assert(largs.size() == apply_args.size());
1026         hnv = hnv[1].substitute(
1027             largs.begin(), largs.end(), apply_args.begin(), apply_args.end());
1028         hnv = Rewriter::rewrite(hnv);
1029       }
1030       Assert(!TypeNode::leastCommonTypeNode(hnv.getType(), curr.getType())
1031                   .isNull());
1032       curr = NodeManager::currentNM()->mkNode(kind::ITE, hni, hnv, curr);
1033     }
1034   }
1035   Node val = NodeManager::currentNM()->mkNode(
1036       kind::LAMBDA,
1037       NodeManager::currentNM()->mkNode(kind::BOUND_VAR_LIST, args),
1038       curr);
1039   m->assignFunctionDefinition(f, val);
1040 }
1041
1042 // This struct is used to sort terms by the "size" of their type
1043 //   The size of the type is the number of nodes in the type, for example
1044 //  size of Int is 1
1045 //  size of Function( Int, Int ) is 3
1046 //  size of Function( Function( Bool, Int ), Int ) is 5
1047 struct sortTypeSize
1048 {
1049   // stores the size of the type
1050   std::map<TypeNode, unsigned> d_type_size;
1051   // get the size of type tn
1052   unsigned getTypeSize(TypeNode tn)
1053   {
1054     std::map<TypeNode, unsigned>::iterator it = d_type_size.find(tn);
1055     if (it != d_type_size.end())
1056     {
1057       return it->second;
1058     }
1059     else
1060     {
1061       unsigned sum = 1;
1062       for (unsigned i = 0; i < tn.getNumChildren(); i++)
1063       {
1064         sum += getTypeSize(tn[i]);
1065       }
1066       d_type_size[tn] = sum;
1067       return sum;
1068     }
1069   }
1070
1071  public:
1072   // compares the type size of i and j
1073   // returns true iff the size of i is less than that of j
1074   // tiebreaks are determined by node value
1075   bool operator()(Node i, Node j)
1076   {
1077     int si = getTypeSize(i.getType());
1078     int sj = getTypeSize(j.getType());
1079     if (si < sj)
1080     {
1081       return true;
1082     }
1083     else if (si == sj)
1084     {
1085       return i < j;
1086     }
1087     else
1088     {
1089       return false;
1090     }
1091   }
1092 };
1093
1094 void TheoryEngineModelBuilder::assignFunctions(TheoryModel* m)
1095 {
1096   Trace("model-builder") << "Assigning function values..." << std::endl;
1097   std::vector<Node> funcs_to_assign = m->getFunctionsToAssign();
1098
1099   if (options::ufHo())
1100   {
1101     // sort based on type size if higher-order
1102     Trace("model-builder") << "Sort functions by type..." << std::endl;
1103     sortTypeSize sts;
1104     std::sort(funcs_to_assign.begin(), funcs_to_assign.end(), sts);
1105   }
1106
1107   if (Trace.isOn("model-builder"))
1108   {
1109     Trace("model-builder") << "...have " << funcs_to_assign.size()
1110                            << " functions to assign:" << std::endl;
1111     for (unsigned k = 0; k < funcs_to_assign.size(); k++)
1112     {
1113       Node f = funcs_to_assign[k];
1114       Trace("model-builder") << "  [" << k << "] : " << f << " : "
1115                              << f.getType() << std::endl;
1116     }
1117   }
1118
1119   // construct function values
1120   for (unsigned k = 0; k < funcs_to_assign.size(); k++)
1121   {
1122     Node f = funcs_to_assign[k];
1123     Trace("model-builder") << "  Function #" << k << " is " << f << std::endl;
1124     // std::map< Node, std::vector< Node > >::iterator itht =
1125     // m->d_ho_uf_terms.find( f );
1126     if (!options::ufHo())
1127     {
1128       Trace("model-builder") << "  Assign function value for " << f
1129                              << " based on APPLY_UF" << std::endl;
1130       assignFunction(m, f);
1131     }
1132     else
1133     {
1134       Trace("model-builder") << "  Assign function value for " << f
1135                              << " based on curried HO_APPLY" << std::endl;
1136       assignHoFunction(m, f);
1137     }
1138   }
1139   Trace("model-builder") << "Finished assigning function values." << std::endl;
1140 }
1141
1142 } /* namespace CVC4::theory */
1143 } /* namespace CVC4 */