src/theory/theory_model_builder.cpp

   1 /*********************                                                        */
   2 /*! \file theory_model_builder.cpp
   3  ** \verbatim
   4  ** Top contributors (to current version):
   5  **   Andrew Reynolds, Clark Barrett, Andres Noetzli
   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 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 if (n.getKind() == kind::FLOATINGPOINT_COMPONENT_SIGN)
  51   {
  52     // Extracting the sign of a floating-point number acts similar to a
  53     // selector on a datatype, i.e. if `(sign x)` wasn't assigned a value, we
  54     // can pick an arbitrary one. Note that the other components of a
  55     // floating-point number should always be assigned a value.
  56     return true;
  57   }
  58   else
  59   {
  60     // non-function variables, and fully applied functions
  61     if (!options::ufHo())
  62     {
  63       // no functions exist, all functions are fully applied
  64       Assert(n.getKind() != kind::HO_APPLY);
  65       Assert(!n.getType().isFunction());
  66       return n.isVar() || n.getKind() == kind::APPLY_UF;
  67     }
  68     else
  69     {
  70       // Assert( n.getKind() != kind::APPLY_UF );
  71       return (n.isVar() && !n.getType().isFunction())
  72              || n.getKind() == kind::APPLY_UF
  73              || (n.getKind() == kind::HO_APPLY
  74                  && n[0].getType().getNumChildren() == 2);
  75     }
  76   }
  77 }
  78
  79 void TheoryEngineModelBuilder::addAssignableSubterms(TNode n,
  80                                                      TheoryModel* tm,
  81                                                      NodeSet& cache)
  82 {
  83   if (n.isClosure())
  84   {
  85     return;
  86   }
  87   if (cache.find(n) != cache.end())
  88   {
  89     return;
  90   }
  91   if (isAssignable(n))
  92   {
  93     tm->d_equalityEngine->addTerm(n);
  94   }
  95   for (TNode::iterator child_it = n.begin(); child_it != n.end(); ++child_it)
  96   {
  97     addAssignableSubterms(*child_it, tm, cache);
  98   }
  99   cache.insert(n);
 100 }
 101
 102 void TheoryEngineModelBuilder::assignConstantRep(TheoryModel* tm,
 103                                                  Node eqc,
 104                                                  Node const_rep)
 105 {
 106   d_constantReps[eqc] = const_rep;
 107   Trace("model-builder") << "    Assign: Setting constant rep of " << eqc
 108                          << " to " << const_rep << endl;
 109   tm->d_rep_set.setTermForRepresentative(const_rep, eqc);
 110 }
 111
 112 bool TheoryEngineModelBuilder::isExcludedCdtValue(
 113     Node val,
 114     std::set<Node>* repSet,
 115     std::map<Node, Node>& assertedReps,
 116     Node eqc)
 117 {
 118   Trace("model-builder-debug")
 119       << "Is " << val << " and excluded codatatype value for " << eqc << "? "
 120       << std::endl;
 121   for (set<Node>::iterator i = repSet->begin(); i != repSet->end(); ++i)
 122   {
 123     Assert(assertedReps.find(*i) != assertedReps.end());
 124     Node rep = assertedReps[*i];
 125     Trace("model-builder-debug") << "  Rep : " << rep << std::endl;
 126     // check matching val to rep with eqc as a free variable
 127     Node eqc_m;
 128     if (isCdtValueMatch(val, rep, eqc, eqc_m))
 129     {
 130       Trace("model-builder-debug") << "  ...matches with " << eqc << " -> "
 131                                    << eqc_m << std::endl;
 132       if (eqc_m.getKind() == kind::UNINTERPRETED_CONSTANT)
 133       {
 134         Trace("model-builder-debug") << "*** " << val
 135                                      << " is excluded datatype for " << eqc
 136                                      << std::endl;
 137         return true;
 138       }
 139     }
 140   }
 141   return false;
 142 }
 143
 144 bool TheoryEngineModelBuilder::isCdtValueMatch(Node v,
 145                                                Node r,
 146                                                Node eqc,
 147                                                Node& eqc_m)
 148 {
 149   if (r == v)
 150   {
 151     return true;
 152   }
 153   else if (r == eqc)
 154   {
 155     if (eqc_m.isNull())
 156     {
 157       // only if an uninterpreted constant?
 158       eqc_m = v;
 159       return true;
 160     }
 161     else
 162     {
 163       return v == eqc_m;
 164     }
 165   }
 166   else if (v.getKind() == kind::APPLY_CONSTRUCTOR
 167            && r.getKind() == kind::APPLY_CONSTRUCTOR)
 168   {
 169     if (v.getOperator() == r.getOperator())
 170     {
 171       for (unsigned i = 0; i < v.getNumChildren(); i++)
 172       {
 173         if (!isCdtValueMatch(v[i], r[i], eqc, eqc_m))
 174         {
 175           return false;
 176         }
 177       }
 178       return true;
 179     }
 180   }
 181   return false;
 182 }
 183
 184 bool TheoryEngineModelBuilder::involvesUSort(TypeNode tn)
 185 {
 186   if (tn.isSort())
 187   {
 188     return true;
 189   }
 190   else if (tn.isArray())
 191   {
 192     return involvesUSort(tn.getArrayIndexType())
 193            || involvesUSort(tn.getArrayConstituentType());
 194   }
 195   else if (tn.isSet())
 196   {
 197     return involvesUSort(tn.getSetElementType());
 198   }
 199   else if (tn.isDatatype())
 200   {
 201     const Datatype& dt = ((DatatypeType)(tn).toType()).getDatatype();
 202     return dt.involvesUninterpretedType();
 203   }
 204   else
 205   {
 206     return false;
 207   }
 208 }
 209
 210 bool TheoryEngineModelBuilder::isExcludedUSortValue(
 211     std::map<TypeNode, unsigned>& eqc_usort_count,
 212     Node v,
 213     std::map<Node, bool>& visited)
 214 {
 215   Assert(v.isConst());
 216   if (visited.find(v) == visited.end())
 217   {
 218     visited[v] = true;
 219     TypeNode tn = v.getType();
 220     if (tn.isSort())
 221     {
 222       Trace("model-builder-debug") << "Is excluded usort value : " << v << " "
 223                                    << tn << std::endl;
 224       unsigned card = eqc_usort_count[tn];
 225       Trace("model-builder-debug") << "  Cardinality is " << card << std::endl;
 226       unsigned index =
 227           v.getConst<UninterpretedConstant>().getIndex().toUnsignedInt();
 228       Trace("model-builder-debug") << "  Index is " << index << std::endl;
 229       return index > 0 && index >= card;
 230     }
 231     for (unsigned i = 0; i < v.getNumChildren(); i++)
 232     {
 233       if (isExcludedUSortValue(eqc_usort_count, v[i], visited))
 234       {
 235         return true;
 236       }
 237     }
 238   }
 239   return false;
 240 }
 241
 242 void TheoryEngineModelBuilder::addToTypeList(
 243     TypeNode tn,
 244     std::vector<TypeNode>& type_list,
 245     std::unordered_set<TypeNode, TypeNodeHashFunction>& visiting)
 246 {
 247   if (std::find(type_list.begin(), type_list.end(), tn) == type_list.end())
 248   {
 249     if (visiting.find(tn) == visiting.end())
 250     {
 251       visiting.insert(tn);
 252       /* This must make a recursive call on all types that are subterms of
 253        * values of the current type.
 254        * Note that recursive traversal here is over enumerated expressions
 255        * (very low expression depth). */
 256       if (tn.isArray())
 257       {
 258         addToTypeList(tn.getArrayIndexType(), type_list, visiting);
 259         addToTypeList(tn.getArrayConstituentType(), type_list, visiting);
 260       }
 261       else if (tn.isSet())
 262       {
 263         addToTypeList(tn.getSetElementType(), type_list, visiting);
 264       }
 265       else if (tn.isDatatype())
 266       {
 267         const Datatype& dt = ((DatatypeType)(tn).toType()).getDatatype();
 268         for (unsigned i = 0; i < dt.getNumConstructors(); i++)
 269         {
 270           for (unsigned j = 0; j < dt[i].getNumArgs(); j++)
 271           {
 272             TypeNode ctn = TypeNode::fromType(dt[i][j].getRangeType());
 273             addToTypeList(ctn, type_list, visiting);
 274           }
 275         }
 276       }
 277       Assert(std::find(type_list.begin(), type_list.end(), tn)
 278              == type_list.end());
 279       type_list.push_back(tn);
 280     }
 281   }
 282 }
 283
 284 bool TheoryEngineModelBuilder::buildModel(Model* m)
 285 {
 286   Trace("model-builder") << "TheoryEngineModelBuilder: buildModel" << std::endl;
 287   TheoryModel* tm = (TheoryModel*)m;
 288
 289   // buildModel should only be called once per check
 290   Assert(!tm->isBuilt());
 291
 292   // Reset model
 293   tm->reset();
 294
 295   // mark as built
 296   tm->d_modelBuilt = true;
 297   tm->d_modelBuiltSuccess = false;
 298
 299   // Collect model info from the theories
 300   Trace("model-builder") << "TheoryEngineModelBuilder: Collect model info..."
 301                          << std::endl;
 302   if (!d_te->collectModelInfo(tm))
 303   {
 304     return false;
 305   }
 306
 307   // model-builder specific initialization
 308   if (!preProcessBuildModel(tm))
 309   {
 310     return false;
 311   }
 312
 313   // Loop through all terms and make sure that assignable sub-terms are in the
 314   // equality engine
 315   // Also, record #eqc per type (for finite model finding)
 316   std::map<TypeNode, unsigned> eqc_usort_count;
 317   eq::EqClassesIterator eqcs_i = eq::EqClassesIterator(tm->d_equalityEngine);
 318   {
 319     NodeSet cache;
 320     for (; !eqcs_i.isFinished(); ++eqcs_i)
 321     {
 322       eq::EqClassIterator eqc_i =
 323           eq::EqClassIterator((*eqcs_i), tm->d_equalityEngine);
 324       for (; !eqc_i.isFinished(); ++eqc_i)
 325       {
 326         addAssignableSubterms(*eqc_i, tm, cache);
 327       }
 328       TypeNode tn = (*eqcs_i).getType();
 329       if (tn.isSort())
 330       {
 331         if (eqc_usort_count.find(tn) == eqc_usort_count.end())
 332         {
 333           eqc_usort_count[tn] = 1;
 334         }
 335         else
 336         {
 337           eqc_usort_count[tn]++;
 338         }
 339       }
 340     }
 341   }
 342
 343   Trace("model-builder") << "Collect representatives..." << std::endl;
 344
 345   // Process all terms in the equality engine, store representatives for each EC
 346   d_constantReps.clear();
 347   std::map<Node, Node> assertedReps;
 348   TypeSet typeConstSet, typeRepSet, typeNoRepSet;
 349   TypeEnumeratorProperties tep;
 350   if (options::finiteModelFind())
 351   {
 352     tep.d_fixed_usort_card = true;
 353     for (std::map<TypeNode, unsigned>::iterator it = eqc_usort_count.begin();
 354          it != eqc_usort_count.end();
 355          ++it)
 356     {
 357       Trace("model-builder") << "Fixed bound (#eqc) for " << it->first << " : "
 358                              << it->second << std::endl;
 359       tep.d_fixed_card[it->first] = Integer(it->second);
 360     }
 361     typeConstSet.setTypeEnumeratorProperties(&tep);
 362   }
 363   // AJR: build ordered list of types that ensures that base types are
 364   // enumerated first.
 365   // (I think) this is only strictly necessary for finite model finding +
 366   // parametric types instantiated with uninterpreted sorts, but is probably
 367   // a good idea to do in general since it leads to models with smaller term
 368   // sizes.
 369   std::vector<TypeNode> type_list;
 370   eqcs_i = eq::EqClassesIterator(tm->d_equalityEngine);
 371   for (; !eqcs_i.isFinished(); ++eqcs_i)
 372   {
 373     // eqc is the equivalence class representative
 374     Node eqc = (*eqcs_i);
 375     Trace("model-builder") << "Processing EC: " << eqc << endl;
 376     Assert(tm->d_equalityEngine->getRepresentative(eqc) == eqc);
 377     TypeNode eqct = eqc.getType();
 378     Assert(assertedReps.find(eqc) == assertedReps.end());
 379     Assert(d_constantReps.find(eqc) == d_constantReps.end());
 380
 381     // Loop through terms in this EC
 382     Node rep, const_rep;
 383     eq::EqClassIterator eqc_i = eq::EqClassIterator(eqc, tm->d_equalityEngine);
 384     for (; !eqc_i.isFinished(); ++eqc_i)
 385     {
 386       Node n = *eqc_i;
 387       Trace("model-builder") << "  Processing Term: " << n << endl;
 388       // Record as rep if this node was specified as a representative
 389       if (tm->d_reps.find(n) != tm->d_reps.end())
 390       {
 391         // AJR: I believe this assertion is too strict,
 392         // e.g. datatypes may assert representative for two constructor terms
 393         // that are not in the care graph and are merged during
 394         // collectModelInfo.
 395         // Assert(rep.isNull());
 396         rep = tm->d_reps[n];
 397         Assert(!rep.isNull());
 398         Trace("model-builder") << "  Rep( " << eqc << " ) = " << rep
 399                                << std::endl;
 400       }
 401       // Record as const_rep if this node is constant
 402       if (n.isConst())
 403       {
 404         Assert(const_rep.isNull());
 405         const_rep = n;
 406         Trace("model-builder") << "  ConstRep( " << eqc << " ) = " << const_rep
 407                                << std::endl;
 408       }
 409       // model-specific processing of the term
 410       tm->addTermInternal(n);
 411     }
 412
 413     // Assign representative for this EC
 414     if (!const_rep.isNull())
 415     {
 416       // Theories should not specify a rep if there is already a constant in the
 417       // EC
 418       // AJR: I believe this assertion is too strict, eqc with asserted reps may
 419       // merge with constant eqc
 420       // Assert(rep.isNull() || rep == const_rep);
 421       assignConstantRep(tm, eqc, const_rep);
 422       typeConstSet.add(eqct.getBaseType(), const_rep);
 423     }
 424     else if (!rep.isNull())
 425     {
 426       assertedReps[eqc] = rep;
 427       typeRepSet.add(eqct.getBaseType(), eqc);
 428       std::unordered_set<TypeNode, TypeNodeHashFunction> visiting;
 429       addToTypeList(eqct.getBaseType(), type_list, visiting);
 430     }
 431     else
 432     {
 433       typeNoRepSet.add(eqct, eqc);
 434       std::unordered_set<TypeNode, TypeNodeHashFunction> visiting;
 435       addToTypeList(eqct, type_list, visiting);
 436     }
 437   }
 438
 439   // Need to ensure that each EC has a constant representative.
 440
 441   Trace("model-builder") << "Processing EC's..." << std::endl;
 442
 443   TypeSet::iterator it;
 444   vector<TypeNode>::iterator type_it;
 445   set<Node>::iterator i, i2;
 446   bool changed, unassignedAssignable, assignOne = false;
 447   set<TypeNode> evaluableSet;
 448
 449   // Double-fixed-point loop
 450   // Outer loop handles a special corner case (see code at end of loop for
 451   // details)
 452   for (;;)
 453   {
 454     // Inner fixed-point loop: we are trying to learn constant values for every
 455     // EC.  Each time through this loop, we process all of the
 456     // types by type and may learn some new EC values.  EC's in one type may
 457     // depend on EC's in another type, so we need a fixed-point loop
 458     // to ensure that we learn as many EC values as possible
 459     do
 460     {
 461       changed = false;
 462       unassignedAssignable = false;
 463       evaluableSet.clear();
 464
 465       // Iterate over all types we've seen
 466       for (type_it = type_list.begin(); type_it != type_list.end(); ++type_it)
 467       {
 468         TypeNode t = *type_it;
 469         TypeNode tb = t.getBaseType();
 470         set<Node>* noRepSet = typeNoRepSet.getSet(t);
 471
 472         // 1. Try to evaluate the EC's in this type
 473         if (noRepSet != NULL && !noRepSet->empty())
 474         {
 475           Trace("model-builder") << "  Eval phase, working on type: " << t
 476                                  << endl;
 477           bool assignable, evaluable, evaluated;
 478           d_normalizedCache.clear();
 479           for (i = noRepSet->begin(); i != noRepSet->end();)
 480           {
 481             i2 = i;
 482             ++i;
 483             assignable = false;
 484             evaluable = false;
 485             evaluated = false;
 486             Trace("model-builder-debug") << "Look at eqc : " << (*i2)
 487                                          << std::endl;
 488             eq::EqClassIterator eqc_i =
 489                 eq::EqClassIterator(*i2, tm->d_equalityEngine);
 490             for (; !eqc_i.isFinished(); ++eqc_i)
 491             {
 492               Node n = *eqc_i;
 493               Trace("model-builder-debug") << "Look at term : " << n
 494                                            << std::endl;
 495               if (isAssignable(n))
 496               {
 497                 assignable = true;
 498                 Trace("model-builder-debug") << "...assignable" << std::endl;
 499               }
 500               else
 501               {
 502                 evaluable = true;
 503                 Trace("model-builder-debug") << "...try to normalize"
 504                                              << std::endl;
 505                 Node normalized = normalize(tm, n, true);
 506                 if (normalized.isConst())
 507                 {
 508                   typeConstSet.add(tb, normalized);
 509                   assignConstantRep(tm, *i2, normalized);
 510                   Trace("model-builder") << "    Eval: Setting constant rep of "
 511                                          << (*i2) << " to " << normalized
 512                                          << endl;
 513                   changed = true;
 514                   evaluated = true;
 515                   noRepSet->erase(i2);
 516                   break;
 517                 }
 518               }
 519             }
 520             if (!evaluated)
 521             {
 522               if (evaluable)
 523               {
 524                 evaluableSet.insert(tb);
 525               }
 526               if (assignable)
 527               {
 528                 unassignedAssignable = true;
 529               }
 530             }
 531           }
 532         }
 533
 534         // 2. Normalize any non-const representative terms for this type
 535         set<Node>* repSet = typeRepSet.getSet(t);
 536         if (repSet != NULL && !repSet->empty())
 537         {
 538           Trace("model-builder")
 539               << "  Normalization phase, working on type: " << t << endl;
 540           d_normalizedCache.clear();
 541           for (i = repSet->begin(); i != repSet->end();)
 542           {
 543             Assert(assertedReps.find(*i) != assertedReps.end());
 544             Node rep = assertedReps[*i];
 545             Node normalized = normalize(tm, rep, false);
 546             Trace("model-builder") << "    Normalizing rep (" << rep
 547                                    << "), normalized to (" << normalized << ")"
 548                                    << endl;
 549             if (normalized.isConst())
 550             {
 551               changed = true;
 552               typeConstSet.add(tb, normalized);
 553               assignConstantRep(tm, *i, normalized);
 554               assertedReps.erase(*i);
 555               i2 = i;
 556               ++i;
 557               repSet->erase(i2);
 558             }
 559             else
 560             {
 561               if (normalized != rep)
 562               {
 563                 assertedReps[*i] = normalized;
 564                 changed = true;
 565               }
 566               ++i;
 567             }
 568           }
 569         }
 570       }
 571     } while (changed);
 572
 573     if (!unassignedAssignable)
 574     {
 575       break;
 576     }
 577
 578     // 3. Assign unassigned assignable EC's using type enumeration - assign a
 579     // value *different* from all other EC's if the type is infinite
 580     // Assign first value from type enumerator otherwise - for finite types, we
 581     // rely on polite framework to ensure that EC's that have to be
 582     // different are different.
 583
 584     // Only make assignments on a type if:
 585     // 1. there are no terms that share the same base type with un-normalized
 586     // representatives
 587     // 2. there are no terms that share teh same base type that are unevaluated
 588     // evaluable terms
 589     // Alternatively, if 2 or 3 don't hold but we are in a special
 590     // deadlock-breaking mode where assignOne is true, go ahead and make one
 591     // assignment
 592     changed = false;
 593     // must iterate over the ordered type list to ensure that we do not
 594     // enumerate values with subterms
 595     //  having types that we are currently enumerating (when possible)
 596     //  for example, this ensures we enumerate uninterpreted sort U before (List
 597     //  of U) and (Array U U)
 598     //  however, it does not break cyclic type dependencies for mutually
 599     //  recursive datatypes, but this is handled
 600     //  by recording all subterms of enumerated values in TypeSet::addSubTerms.
 601     for (type_it = type_list.begin(); type_it != type_list.end(); ++type_it)
 602     {
 603       TypeNode t = *type_it;
 604       // continue if there are no more equivalence classes of this type to
 605       // assign
 606       std::set<Node>* noRepSetPtr = typeNoRepSet.getSet(t);
 607       if (noRepSetPtr == NULL)
 608       {
 609         continue;
 610       }
 611       set<Node>& noRepSet = *noRepSetPtr;
 612       if (noRepSet.empty())
 613       {
 614         continue;
 615       }
 616
 617       // get properties of this type
 618       bool isCorecursive = false;
 619       if (t.isDatatype())
 620       {
 621         const Datatype& dt = ((DatatypeType)(t).toType()).getDatatype();
 622         isCorecursive =
 623             dt.isCodatatype() && (!dt.isFinite(t.toType())
 624                                   || dt.isRecursiveSingleton(t.toType()));
 625       }
 626 #ifdef CVC4_ASSERTIONS
 627       bool isUSortFiniteRestricted = false;
 628       if (options::finiteModelFind())
 629       {
 630         isUSortFiniteRestricted = !t.isSort() && involvesUSort(t);
 631       }
 632 #endif
 633
 634       set<Node>* repSet = typeRepSet.getSet(t);
 635       TypeNode tb = t.getBaseType();
 636       if (!assignOne)
 637       {
 638         set<Node>* repSet = typeRepSet.getSet(tb);
 639         if (repSet != NULL && !repSet->empty())
 640         {
 641           continue;
 642         }
 643         if (evaluableSet.find(tb) != evaluableSet.end())
 644         {
 645           continue;
 646         }
 647       }
 648       Trace("model-builder") << "  Assign phase, working on type: " << t
 649                              << endl;
 650       bool assignable, evaluable CVC4_UNUSED;
 651       for (i = noRepSet.begin(); i != noRepSet.end();)
 652       {
 653         i2 = i;
 654         ++i;
 655         eq::EqClassIterator eqc_i =
 656             eq::EqClassIterator(*i2, tm->d_equalityEngine);
 657         assignable = false;
 658         evaluable = false;
 659         for (; !eqc_i.isFinished(); ++eqc_i)
 660         {
 661           Node n = *eqc_i;
 662           if (isAssignable(n))
 663           {
 664             assignable = true;
 665           }
 666           else
 667           {
 668             evaluable = true;
 669           }
 670         }
 671         Trace("model-builder-debug")
 672             << "    eqc " << *i2 << " is assignable=" << assignable
 673             << ", evaluable=" << evaluable << std::endl;
 674         if (assignable)
 675         {
 676           Assert(!evaluable || assignOne);
 677           // this assertion ensures that if we are assigning to a term of
 678           // Boolean type, then the term is either a variable or an APPLY_UF.
 679           // Note we only assign to terms of Boolean type if the term occurs in
 680           // a singleton equivalence class; otherwise the term would have been
 681           // in the equivalence class of true or false and would not need
 682           // assigning.
 683           Assert(!t.isBoolean() || (*i2).isVar()
 684                  || (*i2).getKind() == kind::APPLY_UF);
 685           Node n;
 686           if (t.getCardinality().isInfinite())
 687           {
 688             // if (!t.isInterpretedFinite()) {
 689             bool success;
 690             do
 691             {
 692               Trace("model-builder-debug") << "Enumerate term of type " << t
 693                                            << std::endl;
 694               n = typeConstSet.nextTypeEnum(t, true);
 695               //--- AJR: this code checks whether n is a legal value
 696               Assert(!n.isNull());
 697               success = true;
 698               Trace("model-builder-debug") << "Check if excluded : " << n
 699                                            << std::endl;
 700 #ifdef CVC4_ASSERTIONS
 701               if (isUSortFiniteRestricted)
 702               {
 703                 // must not involve uninterpreted constants beyond cardinality
 704                 // bound (which assumed to coincide with #eqc)
 705                 // this is just an assertion now, since TypeEnumeratorProperties
 706                 // should ensure that only legal values are enumerated wrt this
 707                 // constraint.
 708                 std::map<Node, bool> visited;
 709                 success = !isExcludedUSortValue(eqc_usort_count, n, visited);
 710                 if (!success)
 711                 {
 712                   Trace("model-builder")
 713                       << "Excluded value for " << t << " : " << n
 714                       << " due to out of range uninterpreted constant."
 715                       << std::endl;
 716                 }
 717                 Assert(success);
 718               }
 719 #endif
 720               if (success && isCorecursive)
 721               {
 722                 if (repSet != NULL && !repSet->empty())
 723                 {
 724                   // in the case of codatatypes, check if it is in the set of
 725                   // values that we cannot assign
 726                   success = !isExcludedCdtValue(n, repSet, assertedReps, *i2);
 727                   if (!success)
 728                   {
 729                     Trace("model-builder")
 730                         << "Excluded value : " << n
 731                         << " due to alpha-equivalent codatatype expression."
 732                         << std::endl;
 733                   }
 734                 }
 735               }
 736               //---
 737             } while (!success);
 738           }
 739           else
 740           {
 741             TypeEnumerator te(t);
 742             n = *te;
 743           }
 744           Assert(!n.isNull());
 745           assignConstantRep(tm, *i2, n);
 746           changed = true;
 747           noRepSet.erase(i2);
 748           if (assignOne)
 749           {
 750             assignOne = false;
 751             break;
 752           }
 753         }
 754       }
 755     }
 756
 757     // Corner case - I'm not sure this can even happen - but it's theoretically
 758     // possible to have a cyclical dependency
 759     // in EC assignment/evaluation, e.g. EC1 = {a, b + 1}; EC2 = {b, a - 1}.  In
 760     // this case, neither one will get assigned because we are waiting
 761     // to be able to evaluate.  But we will never be able to evaluate because
 762     // the variables that need to be assigned are in
 763     // these same EC's.  In this case, repeat the whole fixed-point computation
 764     // with the difference that the first EC
 765     // that has both assignable and evaluable expressions will get assigned.
 766     if (!changed)
 767     {
 768       Assert(!assignOne);  // check for infinite loop!
 769       assignOne = true;
 770     }
 771   }
 772
 773 #ifdef CVC4_ASSERTIONS
 774   // Assert that all representatives have been converted to constants
 775   for (it = typeRepSet.begin(); it != typeRepSet.end(); ++it)
 776   {
 777     set<Node>& repSet = TypeSet::getSet(it);
 778     if (!repSet.empty())
 779     {
 780       Trace("model-builder") << "***Non-empty repSet, size = " << repSet.size()
 781                              << ", first = " << *(repSet.begin()) << endl;
 782       Assert(false);
 783     }
 784   }
 785 #endif /* CVC4_ASSERTIONS */
 786
 787   Trace("model-builder") << "Copy representatives to model..." << std::endl;
 788   tm->d_reps.clear();
 789   std::map<Node, Node>::iterator itMap;
 790   for (itMap = d_constantReps.begin(); itMap != d_constantReps.end(); ++itMap)
 791   {
 792     tm->d_reps[itMap->first] = itMap->second;
 793     tm->d_rep_set.add(itMap->second.getType(), itMap->second);
 794   }
 795
 796   Trace("model-builder") << "Make sure ECs have reps..." << std::endl;
 797   // Make sure every EC has a rep
 798   for (itMap = assertedReps.begin(); itMap != assertedReps.end(); ++itMap)
 799   {
 800     tm->d_reps[itMap->first] = itMap->second;
 801     tm->d_rep_set.add(itMap->second.getType(), itMap->second);
 802   }
 803   for (it = typeNoRepSet.begin(); it != typeNoRepSet.end(); ++it)
 804   {
 805     set<Node>& noRepSet = TypeSet::getSet(it);
 806     set<Node>::iterator i;
 807     for (i = noRepSet.begin(); i != noRepSet.end(); ++i)
 808     {
 809       tm->d_reps[*i] = *i;
 810       tm->d_rep_set.add((*i).getType(), *i);
 811     }
 812   }
 813
 814   // modelBuilder-specific initialization
 815   if (!processBuildModel(tm))
 816   {
 817     return false;
 818   }
 819
 820   tm->d_modelBuiltSuccess = true;
 821   return true;
 822 }
 823
 824 void TheoryEngineModelBuilder::postProcessModel(bool incomplete, Model* m)
 825 {
 826   // if we are incomplete, there is no guarantee on the model.
 827   // thus, we do not check the model here.
 828   if (incomplete)
 829   {
 830     return;
 831   }
 832   TheoryModel* tm = static_cast<TheoryModel*>(m);
 833   Assert(tm != nullptr);
 834   // debug-check the model if the checkModels() is enabled.
 835   if (options::checkModels())
 836   {
 837     debugCheckModel(tm);
 838   }
 839 }
 840
 841 void TheoryEngineModelBuilder::debugCheckModel(TheoryModel* tm)
 842 {
 843 #ifdef CVC4_ASSERTIONS
 844   Assert(tm->isBuilt());
 845   eq::EqClassesIterator eqcs_i = eq::EqClassesIterator(tm->d_equalityEngine);
 846   std::map<Node, Node>::iterator itMap;
 847   // Check that every term evaluates to its representative in the model
 848   for (eqcs_i = eq::EqClassesIterator(tm->d_equalityEngine);
 849        !eqcs_i.isFinished();
 850        ++eqcs_i)
 851   {
 852     // eqc is the equivalence class representative
 853     Node eqc = (*eqcs_i);
 854     // get the representative
 855     Node rep = tm->getRepresentative(eqc);
 856     if (!rep.isConst() && eqc.getType().isBoolean())
 857     {
 858       // if Boolean, it does not necessarily have a constant representative, use
 859       // get value instead
 860       rep = tm->getValue(eqc);
 861       Assert(rep.isConst());
 862     }
 863     eq::EqClassIterator eqc_i = eq::EqClassIterator(eqc, tm->d_equalityEngine);
 864     for (; !eqc_i.isFinished(); ++eqc_i)
 865     {
 866       Node n = *eqc_i;
 867       static int repCheckInstance = 0;
 868       ++repCheckInstance;
 869
 870       // non-linear mult is not necessarily accurate wrt getValue
 871       if (n.getKind() != kind::NONLINEAR_MULT)
 872       {
 873         Debug("check-model::rep-checking") << "( " << repCheckInstance << ") "
 874                                            << "n: " << n << endl
 875                                            << "getValue(n): " << tm->getValue(n)
 876                                            << endl
 877                                            << "rep: " << rep << endl;
 878         Assert(tm->getValue(*eqc_i) == rep,
 879                "run with -d check-model::rep-checking for details");
 880       }
 881     }
 882   }
 883 #endif /* CVC4_ASSERTIONS */
 884
 885   // builder-specific debugging
 886   debugModel(tm);
 887 }
 888
 889 Node TheoryEngineModelBuilder::normalize(TheoryModel* m, TNode r, bool evalOnly)
 890 {
 891   std::map<Node, Node>::iterator itMap = d_constantReps.find(r);
 892   if (itMap != d_constantReps.end())
 893   {
 894     return (*itMap).second;
 895   }
 896   NodeMap::iterator it = d_normalizedCache.find(r);
 897   if (it != d_normalizedCache.end())
 898   {
 899     return (*it).second;
 900   }
 901   Trace("model-builder-debug") << "do normalize on " << r << std::endl;
 902   Node retNode = r;
 903   if (r.getNumChildren() > 0)
 904   {
 905     std::vector<Node> children;
 906     if (r.getMetaKind() == kind::metakind::PARAMETERIZED)
 907     {
 908       children.push_back(r.getOperator());
 909     }
 910     bool childrenConst = true;
 911     for (size_t i = 0; i < r.getNumChildren(); ++i)
 912     {
 913       Node ri = r[i];
 914       bool recurse = true;
 915       if (!ri.isConst())
 916       {
 917         if (m->d_equalityEngine->hasTerm(ri))
 918         {
 919           itMap =
 920               d_constantReps.find(m->d_equalityEngine->getRepresentative(ri));
 921           if (itMap != d_constantReps.end())
 922           {
 923             ri = (*itMap).second;
 924             recurse = false;
 925           }
 926           else if (!evalOnly)
 927           {
 928             recurse = false;
 929           }
 930         }
 931         if (recurse)
 932         {
 933           ri = normalize(m, ri, evalOnly);
 934         }
 935         if (!ri.isConst())
 936         {
 937           childrenConst = false;
 938         }
 939       }
 940       children.push_back(ri);
 941     }
 942     retNode = NodeManager::currentNM()->mkNode(r.getKind(), children);
 943     if (childrenConst)
 944     {
 945       retNode = Rewriter::rewrite(retNode);
 946       Assert(retNode.getKind() == kind::APPLY_UF
 947              || !retNode.getType().isFirstClass()
 948              || retNode.isConst());
 949     }
 950   }
 951   d_normalizedCache[r] = retNode;
 952   return retNode;
 953 }
 954
 955 bool TheoryEngineModelBuilder::preProcessBuildModel(TheoryModel* m)
 956 {
 957   return true;
 958 }
 959
 960 bool TheoryEngineModelBuilder::processBuildModel(TheoryModel* m)
 961 {
 962   if (m->areFunctionValuesEnabled())
 963   {
 964     assignFunctions(m);
 965   }
 966   return true;
 967 }
 968
 969 void TheoryEngineModelBuilder::assignFunction(TheoryModel* m, Node f)
 970 {
 971   Assert(!options::ufHo());
 972   uf::UfModelTree ufmt(f);
 973   Node default_v;
 974   for (size_t i = 0; i < m->d_uf_terms[f].size(); i++)
 975   {
 976     Node un = m->d_uf_terms[f][i];
 977     vector<TNode> children;
 978     children.push_back(f);
 979     Trace("model-builder-debug") << "  process term : " << un << std::endl;
 980     for (size_t j = 0; j < un.getNumChildren(); ++j)
 981     {
 982       Node rc = m->getRepresentative(un[j]);
 983       Trace("model-builder-debug2") << "    get rep : " << un[j] << " returned "
 984                                     << rc << std::endl;
 985       Assert(rc.isConst());
 986       children.push_back(rc);
 987     }
 988     Node simp = NodeManager::currentNM()->mkNode(un.getKind(), children);
 989     Node v = m->getRepresentative(un);
 990     Trace("model-builder") << "  Setting (" << simp << ") to (" << v << ")"
 991                            << endl;
 992     ufmt.setValue(m, simp, v);
 993     default_v = v;
 994   }
 995   if (default_v.isNull())
 996   {
 997     // choose default value from model if none exists
 998     TypeEnumerator te(f.getType().getRangeType());
 999     default_v = (*te);
1000   }
1001   ufmt.setDefaultValue(m, default_v);
1002   bool condenseFuncValues = options::condenseFunctionValues();
1003   if (condenseFuncValues)
1004   {
1005     ufmt.simplify();
1006   }
1007   std::stringstream ss;
1008   ss << "_arg_";
1009   Node val = ufmt.getFunctionValue(ss.str().c_str(), condenseFuncValues);
1010   m->assignFunctionDefinition(f, val);
1011   // ufmt.debugPrint( std::cout, m );
1012 }
1013
1014 void TheoryEngineModelBuilder::assignHoFunction(TheoryModel* m, Node f)
1015 {
1016   Assert(options::ufHo());
1017   TypeNode type = f.getType();
1018   std::vector<TypeNode> argTypes = type.getArgTypes();
1019   std::vector<Node> args;
1020   std::vector<TNode> apply_args;
1021   for (unsigned i = 0; i < argTypes.size(); i++)
1022   {
1023     Node v = NodeManager::currentNM()->mkBoundVar(argTypes[i]);
1024     args.push_back(v);
1025     if (i > 0)
1026     {
1027       apply_args.push_back(v);
1028     }
1029   }
1030   // start with the base return value (currently we use the same default value
1031   // for all functions)
1032   TypeEnumerator te(type.getRangeType());
1033   Node curr = (*te);
1034   std::map<Node, std::vector<Node> >::iterator itht = m->d_ho_uf_terms.find(f);
1035   if (itht != m->d_ho_uf_terms.end())
1036   {
1037     for (size_t i = 0; i < itht->second.size(); i++)
1038     {
1039       Node hn = itht->second[i];
1040       Trace("model-builder-debug") << "    process : " << hn << std::endl;
1041       Assert(hn.getKind() == kind::HO_APPLY);
1042       Assert(m->areEqual(hn[0], f));
1043       Node hni = m->getRepresentative(hn[1]);
1044       Trace("model-builder-debug2") << "      get rep : " << hn[0]
1045                                     << " returned " << hni << std::endl;
1046       Assert(hni.isConst());
1047       Assert(hni.getType().isSubtypeOf(args[0].getType()));
1048       hni = Rewriter::rewrite(args[0].eqNode(hni));
1049       Node hnv = m->getRepresentative(hn);
1050       Trace("model-builder-debug2") << "      get rep val : " << hn
1051                                     << " returned " << hnv << std::endl;
1052       Assert(hnv.isConst());
1053       if (!apply_args.empty())
1054       {
1055         Assert(hnv.getKind() == kind::LAMBDA
1056                && hnv[0].getNumChildren() + 1 == args.size());
1057         std::vector<TNode> largs;
1058         for (unsigned j = 0; j < hnv[0].getNumChildren(); j++)
1059         {
1060           largs.push_back(hnv[0][j]);
1061         }
1062         Assert(largs.size() == apply_args.size());
1063         hnv = hnv[1].substitute(
1064             largs.begin(), largs.end(), apply_args.begin(), apply_args.end());
1065         hnv = Rewriter::rewrite(hnv);
1066       }
1067       Assert(!TypeNode::leastCommonTypeNode(hnv.getType(), curr.getType())
1068                   .isNull());
1069       curr = NodeManager::currentNM()->mkNode(kind::ITE, hni, hnv, curr);
1070     }
1071   }
1072   Node val = NodeManager::currentNM()->mkNode(
1073       kind::LAMBDA,
1074       NodeManager::currentNM()->mkNode(kind::BOUND_VAR_LIST, args),
1075       curr);
1076   m->assignFunctionDefinition(f, val);
1077 }
1078
1079 // This struct is used to sort terms by the "size" of their type
1080 //   The size of the type is the number of nodes in the type, for example
1081 //  size of Int is 1
1082 //  size of Function( Int, Int ) is 3
1083 //  size of Function( Function( Bool, Int ), Int ) is 5
1084 struct sortTypeSize
1085 {
1086   // stores the size of the type
1087   std::map<TypeNode, unsigned> d_type_size;
1088   // get the size of type tn
1089   unsigned getTypeSize(TypeNode tn)
1090   {
1091     std::map<TypeNode, unsigned>::iterator it = d_type_size.find(tn);
1092     if (it != d_type_size.end())
1093     {
1094       return it->second;
1095     }
1096     else
1097     {
1098       unsigned sum = 1;
1099       for (unsigned i = 0; i < tn.getNumChildren(); i++)
1100       {
1101         sum += getTypeSize(tn[i]);
1102       }
1103       d_type_size[tn] = sum;
1104       return sum;
1105     }
1106   }
1107
1108  public:
1109   // compares the type size of i and j
1110   // returns true iff the size of i is less than that of j
1111   // tiebreaks are determined by node value
1112   bool operator()(Node i, Node j)
1113   {
1114     int si = getTypeSize(i.getType());
1115     int sj = getTypeSize(j.getType());
1116     if (si < sj)
1117     {
1118       return true;
1119     }
1120     else if (si == sj)
1121     {
1122       return i < j;
1123     }
1124     else
1125     {
1126       return false;
1127     }
1128   }
1129 };
1130
1131 void TheoryEngineModelBuilder::assignFunctions(TheoryModel* m)
1132 {
1133   if (!options::assignFunctionValues())
1134   {
1135     return;
1136   }
1137   Trace("model-builder") << "Assigning function values..." << std::endl;
1138   std::vector<Node> funcs_to_assign = m->getFunctionsToAssign();
1139
1140   if (options::ufHo())
1141   {
1142     // sort based on type size if higher-order
1143     Trace("model-builder") << "Sort functions by type..." << std::endl;
1144     sortTypeSize sts;
1145     std::sort(funcs_to_assign.begin(), funcs_to_assign.end(), sts);
1146   }
1147
1148   if (Trace.isOn("model-builder"))
1149   {
1150     Trace("model-builder") << "...have " << funcs_to_assign.size()
1151                            << " functions to assign:" << std::endl;
1152     for (unsigned k = 0; k < funcs_to_assign.size(); k++)
1153     {
1154       Node f = funcs_to_assign[k];
1155       Trace("model-builder") << "  [" << k << "] : " << f << " : "
1156                              << f.getType() << std::endl;
1157     }
1158   }
1159
1160   // construct function values
1161   for (unsigned k = 0; k < funcs_to_assign.size(); k++)
1162   {
1163     Node f = funcs_to_assign[k];
1164     Trace("model-builder") << "  Function #" << k << " is " << f << std::endl;
1165     // std::map< Node, std::vector< Node > >::iterator itht =
1166     // m->d_ho_uf_terms.find( f );
1167     if (!options::ufHo())
1168     {
1169       Trace("model-builder") << "  Assign function value for " << f
1170                              << " based on APPLY_UF" << std::endl;
1171       assignFunction(m, f);
1172     }
1173     else
1174     {
1175       Trace("model-builder") << "  Assign function value for " << f
1176                              << " based on curried HO_APPLY" << std::endl;
1177       assignHoFunction(m, f);
1178     }
1179   }
1180   Trace("model-builder") << "Finished assigning function values." << std::endl;
1181 }
1182
1183 } /* namespace CVC4::theory */
1184 } /* namespace CVC4 */