src/theory/theory_engine.h

   1 /*********************                                                        */
   2 /*! \file theory_engine.h
   3  ** \verbatim
   4  ** Top contributors (to current version):
   5  **   Dejan Jovanovic, Morgan Deters, Andrew Reynolds
   6  ** This file is part of the CVC4 project.
   7  ** Copyright (c) 2009-2018 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 The theory engine
  13  **
  14  ** The theory engine.
  15  **/
  16
  17 #include "cvc4_private.h"
  18
  19 #ifndef __CVC4__THEORY_ENGINE_H
  20 #define __CVC4__THEORY_ENGINE_H
  21
  22 #include <deque>
  23 #include <memory>
  24 #include <set>
  25 #include <unordered_map>
  26 #include <vector>
  27 #include <utility>
  28
  29 #include "base/cvc4_assert.h"
  30 #include "context/cdhashset.h"
  31 #include "expr/node.h"
  32 #include "options/options.h"
  33 #include "options/smt_options.h"
  34 #include "prop/prop_engine.h"
  35 #include "smt/command.h"
  36 #include "smt_util/lemma_channels.h"
  37 #include "theory/atom_requests.h"
  38 #include "theory/decision_manager.h"
  39 #include "theory/interrupted.h"
  40 #include "theory/rewriter.h"
  41 #include "theory/shared_terms_database.h"
  42 #include "theory/sort_inference.h"
  43 #include "theory/substitutions.h"
  44 #include "theory/term_registration_visitor.h"
  45 #include "theory/theory.h"
  46 #include "theory/uf/equality_engine.h"
  47 #include "theory/valuation.h"
  48 #include "util/hash.h"
  49 #include "util/statistics_registry.h"
  50 #include "util/unsafe_interrupt_exception.h"
  51
  52 namespace CVC4 {
  53
  54 class ResourceManager;
  55 class LemmaProofRecipe;
  56
  57 /**
  58  * A pair of a theory and a node. This is used to mark the flow of
  59  * propagations between theories.
  60  */
  61 struct NodeTheoryPair {
  62   Node node;
  63   theory::TheoryId theory;
  64   size_t timestamp;
  65   NodeTheoryPair(TNode node, theory::TheoryId theory, size_t timestamp = 0)
  66   : node(node), theory(theory), timestamp(timestamp) {}
  67   NodeTheoryPair() : theory(theory::THEORY_LAST), timestamp() {}
  68   // Comparison doesn't take into account the timestamp
  69   bool operator == (const NodeTheoryPair& pair) const {
  70     return node == pair.node && theory == pair.theory;
  71   }
  72 };/* struct NodeTheoryPair */
  73
  74 struct NodeTheoryPairHashFunction {
  75   NodeHashFunction hashFunction;
  76   // Hash doesn't take into account the timestamp
  77   size_t operator()(const NodeTheoryPair& pair) const {
  78     uint64_t hash = fnv1a::fnv1a_64(NodeHashFunction()(pair.node));
  79     return static_cast<size_t>(fnv1a::fnv1a_64(pair.theory, hash));
  80   }
  81 };/* struct NodeTheoryPairHashFunction */
  82
  83
  84 /* Forward declarations */
  85 namespace theory {
  86   class TheoryModel;
  87   class TheoryEngineModelBuilder;
  88
  89   namespace eq {
  90     class EqualityEngine;
  91   }/* CVC4::theory::eq namespace */
  92
  93   namespace quantifiers {
  94     class TermDb;
  95   }
  96
  97   class EntailmentCheckParameters;
  98   class EntailmentCheckSideEffects;
  99 }/* CVC4::theory namespace */
 100
 101 class DecisionEngine;
 102 class RemoveTermFormulas;
 103
 104 /**
 105  * This is essentially an abstraction for a collection of theories.  A
 106  * TheoryEngine provides services to a PropEngine, making various
 107  * T-solvers look like a single unit to the propositional part of
 108  * CVC4.
 109  */
 110 class TheoryEngine {
 111
 112   /** Shared terms database can use the internals notify the theories */
 113   friend class SharedTermsDatabase;
 114   friend class theory::quantifiers::TermDb;
 115
 116   /** Associated PropEngine engine */
 117   prop::PropEngine* d_propEngine;
 118
 119   /** Access to decision engine */
 120   DecisionEngine* d_decisionEngine;
 121
 122   /** Our context */
 123   context::Context* d_context;
 124
 125   /** Our user context */
 126   context::UserContext* d_userContext;
 127
 128   /**
 129    * A table of from theory IDs to theory pointers. Never use this table
 130    * directly, use theoryOf() instead.
 131    */
 132   theory::Theory* d_theoryTable[theory::THEORY_LAST];
 133
 134   /**
 135    * A collection of theories that are "active" for the current run.
 136    * This set is provided by the user (as a logic string, say, in SMT-LIBv2
 137    * format input), or else by default it's all-inclusive.  This is important
 138    * because we can optimize for single-theory runs (no sharing), can reduce
 139    * the cost of walking the DAG on registration, etc.
 140    */
 141   const LogicInfo& d_logicInfo;
 142
 143   /**
 144    * The database of shared terms.
 145    */
 146   SharedTermsDatabase d_sharedTerms;
 147
 148   /**
 149    * Master equality engine, to share with theories.
 150    */
 151   theory::eq::EqualityEngine* d_masterEqualityEngine;
 152
 153   /** notify class for master equality engine */
 154   class NotifyClass : public theory::eq::EqualityEngineNotify {
 155     TheoryEngine& d_te;
 156   public:
 157     NotifyClass(TheoryEngine& te): d_te(te) {}
 158     bool eqNotifyTriggerEquality(TNode equality, bool value) override
 159     {
 160       return true;
 161     }
 162     bool eqNotifyTriggerPredicate(TNode predicate, bool value) override
 163     {
 164       return true;
 165     }
 166     bool eqNotifyTriggerTermEquality(theory::TheoryId tag,
 167                                      TNode t1,
 168                                      TNode t2,
 169                                      bool value) override
 170     {
 171       return true;
 172     }
 173     void eqNotifyConstantTermMerge(TNode t1, TNode t2) override {}
 174     void eqNotifyNewClass(TNode t) override { d_te.eqNotifyNewClass(t); }
 175     void eqNotifyPreMerge(TNode t1, TNode t2) override
 176     {
 177       d_te.eqNotifyPreMerge(t1, t2);
 178     }
 179     void eqNotifyPostMerge(TNode t1, TNode t2) override
 180     {
 181       d_te.eqNotifyPostMerge(t1, t2);
 182     }
 183     void eqNotifyDisequal(TNode t1, TNode t2, TNode reason) override
 184     {
 185       d_te.eqNotifyDisequal(t1, t2, reason);
 186     }
 187   };/* class TheoryEngine::NotifyClass */
 188   NotifyClass d_masterEENotify;
 189
 190   /**
 191    * notification methods
 192    */
 193   void eqNotifyNewClass(TNode t);
 194   void eqNotifyPreMerge(TNode t1, TNode t2);
 195   void eqNotifyPostMerge(TNode t1, TNode t2);
 196   void eqNotifyDisequal(TNode t1, TNode t2, TNode reason);
 197
 198   /**
 199    * The quantifiers engine
 200    */
 201   theory::QuantifiersEngine* d_quantEngine;
 202   /**
 203    * The decision manager
 204    */
 205   std::unique_ptr<theory::DecisionManager> d_decManager;
 206
 207   /**
 208    * Default model object
 209    */
 210   theory::TheoryModel* d_curr_model;
 211   bool d_aloc_curr_model;
 212   /**
 213    * Model builder object
 214    */
 215   theory::TheoryEngineModelBuilder* d_curr_model_builder;
 216   bool d_aloc_curr_model_builder;
 217
 218   typedef std::unordered_map<Node, Node, NodeHashFunction> NodeMap;
 219   typedef std::unordered_map<TNode, Node, TNodeHashFunction> TNodeMap;
 220
 221   /**
 222   * Cache for theory-preprocessing of assertions
 223    */
 224   NodeMap d_ppCache;
 225
 226   /**
 227    * Used for "missed-t-propagations" dumping mode only.  A set of all
 228    * theory-propagable literals.
 229    */
 230   context::CDList<TNode> d_possiblePropagations;
 231
 232   /**
 233    * Used for "missed-t-propagations" dumping mode only.  A
 234    * context-dependent set of those theory-propagable literals that
 235    * have been propagated.
 236    */
 237   context::CDHashSet<Node, NodeHashFunction> d_hasPropagated;
 238
 239
 240   /**
 241    * Statistics for a particular theory.
 242    */
 243   class Statistics {
 244
 245     static std::string mkName(std::string prefix,
 246                               theory::TheoryId theory,
 247                               std::string suffix) {
 248       std::stringstream ss;
 249       ss << prefix << theory << suffix;
 250       return ss.str();
 251     }
 252
 253    public:
 254     IntStat conflicts, propagations, lemmas, requirePhase, restartDemands;
 255
 256     Statistics(theory::TheoryId theory);
 257     ~Statistics();
 258   };/* class TheoryEngine::Statistics */
 259
 260   /**
 261    * An output channel for Theory that passes messages
 262    * back to a TheoryEngine.
 263    */
 264   class EngineOutputChannel : public theory::OutputChannel {
 265     friend class TheoryEngine;
 266
 267     /**
 268      * The theory engine we're communicating with.
 269      */
 270     TheoryEngine* d_engine;
 271
 272     /**
 273      * The statistics of the theory interractions.
 274      */
 275     Statistics d_statistics;
 276
 277     /** The theory owning this channel. */
 278     theory::TheoryId d_theory;
 279
 280    public:
 281     EngineOutputChannel(TheoryEngine* engine, theory::TheoryId theory)
 282         : d_engine(engine), d_statistics(theory), d_theory(theory) {}
 283
 284     void safePoint(uint64_t amount) override {
 285       spendResource(amount);
 286       if (d_engine->d_interrupted) {
 287         throw theory::Interrupted();
 288       }
 289     }
 290
 291     void conflict(TNode conflictNode,
 292                   std::unique_ptr<Proof> pf = nullptr) override;
 293     bool propagate(TNode literal) override;
 294
 295     theory::LemmaStatus lemma(TNode lemma, ProofRule rule,
 296                               bool removable = false, bool preprocess = false,
 297                               bool sendAtoms = false) override;
 298
 299     theory::LemmaStatus splitLemma(TNode lemma,
 300                                    bool removable = false) override;
 301
 302     void demandRestart() override {
 303       NodeManager* curr = NodeManager::currentNM();
 304       Node restartVar = curr->mkSkolem(
 305           "restartVar", curr->booleanType(),
 306           "A boolean variable asserted to be true to force a restart");
 307       Trace("theory::restart")
 308           << "EngineOutputChannel<" << d_theory << ">::restart(" << restartVar
 309           << ")" << std::endl;
 310       ++d_statistics.restartDemands;
 311       lemma(restartVar, RULE_INVALID, true);
 312     }
 313
 314     void requirePhase(TNode n, bool phase) override {
 315       Debug("theory") << "EngineOutputChannel::requirePhase(" << n << ", "
 316                       << phase << ")" << std::endl;
 317       ++d_statistics.requirePhase;
 318       d_engine->d_propEngine->requirePhase(n, phase);
 319     }
 320
 321     void setIncomplete() override {
 322       Trace("theory") << "TheoryEngine::setIncomplete()" << std::endl;
 323       d_engine->setIncomplete(d_theory);
 324     }
 325
 326     void spendResource(unsigned amount) override {
 327       d_engine->spendResource(amount);
 328     }
 329
 330     void handleUserAttribute(const char* attr, theory::Theory* t) override {
 331       d_engine->handleUserAttribute(attr, t);
 332     }
 333
 334    private:
 335     /**
 336      * A helper function for registering lemma recipes with the proof engine
 337      */
 338     void registerLemmaRecipe(Node lemma, Node originalLemma, bool preprocess,
 339                              theory::TheoryId theoryId);
 340   }; /* class TheoryEngine::EngineOutputChannel */
 341
 342   /**
 343    * Output channels for individual theories.
 344    */
 345   EngineOutputChannel* d_theoryOut[theory::THEORY_LAST];
 346
 347   /**
 348    * Are we in conflict.
 349    */
 350   context::CDO<bool> d_inConflict;
 351
 352   /**
 353    * Called by the theories to notify of a conflict.
 354    */
 355   void conflict(TNode conflict, theory::TheoryId theoryId);
 356
 357   /**
 358    * Debugging flag to ensure that shutdown() is called before the
 359    * destructor.
 360    */
 361   bool d_hasShutDown;
 362
 363   /**
 364    * True if a theory has notified us of incompleteness (at this
 365    * context level or below).
 366    */
 367   context::CDO<bool> d_incomplete;
 368
 369   /**
 370    * Called by the theories to notify that the current branch is incomplete.
 371    */
 372   void setIncomplete(theory::TheoryId theory) {
 373     d_incomplete = true;
 374   }
 375
 376
 377   /**
 378    * Mapping of propagations from recievers to senders.
 379    */
 380   typedef context::CDHashMap<NodeTheoryPair, NodeTheoryPair, NodeTheoryPairHashFunction> PropagationMap;
 381   PropagationMap d_propagationMap;
 382
 383   /**
 384    * Timestamp of propagations
 385    */
 386   context::CDO<size_t> d_propagationMapTimestamp;
 387
 388   /**
 389    * Literals that are propagated by the theory. Note that these are TNodes.
 390    * The theory can only propagate nodes that have an assigned literal in the
 391    * SAT solver and are hence referenced in the SAT solver.
 392    */
 393   context::CDList<TNode> d_propagatedLiterals;
 394
 395   /**
 396    * The index of the next literal to be propagated by a theory.
 397    */
 398   context::CDO<unsigned> d_propagatedLiteralsIndex;
 399
 400   /**
 401    * Called by the output channel to propagate literals and facts
 402    * @return false if immediate conflict
 403    */
 404   bool propagate(TNode literal, theory::TheoryId theory);
 405
 406   /**
 407    * Internal method to call the propagation routines and collect the
 408    * propagated literals.
 409    */
 410   void propagate(theory::Theory::Effort effort);
 411
 412   /**
 413    * A variable to mark if we added any lemmas.
 414    */
 415   bool d_lemmasAdded;
 416
 417   /**
 418    * A variable to mark if the OutputChannel was "used" by any theory
 419    * since the start of the last check.  If it has been, we require
 420    * a FULL_EFFORT check before exiting and reporting SAT.
 421    *
 422    * See the documentation for the needCheck() function, below.
 423    */
 424   bool d_outputChannelUsed;
 425
 426   /** Atom requests from lemmas */
 427   AtomRequests d_atomRequests;
 428
 429   /**
 430    * Adds a new lemma, returning its status.
 431    * @param node the lemma
 432    * @param negated should the lemma be asserted negated
 433    * @param removable can the lemma be remove (restrictions apply)
 434    * @param needAtoms if not THEORY_LAST, then
 435    */
 436   theory::LemmaStatus lemma(TNode node,
 437                             ProofRule rule,
 438                             bool negated,
 439                             bool removable,
 440                             bool preprocess,
 441                             theory::TheoryId atomsTo);
 442
 443   /** Enusre that the given atoms are send to the given theory */
 444   void ensureLemmaAtoms(const std::vector<TNode>& atoms, theory::TheoryId theory);
 445
 446   RemoveTermFormulas& d_tform_remover;
 447
 448   /** sort inference module */
 449   SortInference d_sortInfer;
 450
 451   /** Time spent in theory combination */
 452   TimerStat d_combineTheoriesTime;
 453
 454   Node d_true;
 455   Node d_false;
 456
 457   /** Whether we were just interrupted (or not) */
 458   bool d_interrupted;
 459   ResourceManager* d_resourceManager;
 460
 461   /** Container for lemma input and output channels. */
 462   LemmaChannels* d_channels;
 463
 464 public:
 465
 466   /** Constructs a theory engine */
 467   TheoryEngine(context::Context* context, context::UserContext* userContext,
 468                RemoveTermFormulas& iteRemover, const LogicInfo& logic,
 469                LemmaChannels* channels);
 470
 471   /** Destroys a theory engine */
 472   ~TheoryEngine();
 473
 474   void interrupt();
 475
 476   /** "Spend" a resource during a search or preprocessing.*/
 477   void spendResource(unsigned amount);
 478
 479   /**
 480    * Adds a theory. Only one theory per TheoryId can be present, so if
 481    * there is another theory it will be deleted.
 482    */
 483   template <class TheoryClass>
 484   inline void addTheory(theory::TheoryId theoryId) {
 485     Assert(d_theoryTable[theoryId] == NULL && d_theoryOut[theoryId] == NULL);
 486     d_theoryOut[theoryId] = new EngineOutputChannel(this, theoryId);
 487     d_theoryTable[theoryId] =
 488         new TheoryClass(d_context, d_userContext, *d_theoryOut[theoryId],
 489                         theory::Valuation(this), d_logicInfo);
 490   }
 491
 492   inline void setPropEngine(prop::PropEngine* propEngine) {
 493     Assert(d_propEngine == NULL);
 494     d_propEngine = propEngine;
 495   }
 496
 497   inline void setDecisionEngine(DecisionEngine* decisionEngine) {
 498     Assert(d_decisionEngine == NULL);
 499     d_decisionEngine = decisionEngine;
 500   }
 501
 502   /** Called when all initialization of options/logic is done */
 503   void finishInit();
 504
 505   /**
 506    * Get a pointer to the underlying propositional engine.
 507    */
 508   inline prop::PropEngine* getPropEngine() const {
 509     return d_propEngine;
 510   }
 511
 512   /**
 513    * Get a pointer to the underlying sat context.
 514    */
 515   inline context::Context* getSatContext() const {
 516     return d_context;
 517   }
 518
 519   /**
 520    * Get a pointer to the underlying user context.
 521    */
 522   inline context::Context* getUserContext() const {
 523     return d_userContext;
 524   }
 525
 526   /**
 527    * Get a pointer to the underlying quantifiers engine.
 528    */
 529   theory::QuantifiersEngine* getQuantifiersEngine() const {
 530     return d_quantEngine;
 531   }
 532   /**
 533    * Get a pointer to the underlying decision manager.
 534    */
 535   theory::DecisionManager* getDecisionManager() const
 536   {
 537     return d_decManager.get();
 538   }
 539
 540  private:
 541   /**
 542    * Helper for preprocess
 543    */
 544   Node ppTheoryRewrite(TNode term);
 545
 546   /**
 547    * Queue of nodes for pre-registration.
 548    */
 549   std::queue<TNode> d_preregisterQueue;
 550
 551   /**
 552    * Boolean flag denoting we are in pre-registration.
 553    */
 554   bool d_inPreregister;
 555
 556   /**
 557    * Did the theories get any new facts since the last time we called
 558    * check()
 559    */
 560   context::CDO<bool> d_factsAsserted;
 561
 562   /**
 563    * Map from equality atoms to theories that would like to be notified about them.
 564    */
 565
 566
 567   /**
 568    * Assert the formula to the given theory.
 569    * @param assertion the assertion to send (not necesserily normalized)
 570    * @param original the assertion as it was sent in from the propagating theory
 571    * @param toTheoryId the theory to assert to
 572    * @param fromTheoryId the theory that sent it
 573    */
 574   void assertToTheory(TNode assertion, TNode originalAssertion, theory::TheoryId toTheoryId, theory::TheoryId fromTheoryId);
 575
 576   /**
 577    * Marks a theory propagation from a theory to a theory where a
 578    * theory could be the THEORY_SAT_SOLVER for literals coming from
 579    * or being propagated to the SAT solver. If the receiving theory
 580    * already recieved the literal, the method returns false, otherwise
 581    * it returns true.
 582    *
 583    * @param assertion the normalized assertion being sent
 584    * @param originalAssertion the actual assertion that was sent
 585    * @param toTheoryId the theory that is on the receiving end
 586    * @param fromTheoryId the theory that sent the assertino
 587    * @return true if a new assertion, false if theory already got it
 588    */
 589   bool markPropagation(TNode assertion, TNode originalAssertions, theory::TheoryId toTheoryId, theory::TheoryId fromTheoryId);
 590
 591   /**
 592    * Computes the explanation by travarsing the propagation graph and
 593    * asking relevant theories to explain the propagations. Initially
 594    * the explanation vector should contain only the element (node, theory)
 595    * where the node is the one to be explained, and the theory is the
 596    * theory that sent the literal. The lemmaProofRecipe will contain a list
 597    * of the explanation steps required to produce the original node.
 598    */
 599   void getExplanation(std::vector<NodeTheoryPair>& explanationVector, LemmaProofRecipe* lemmaProofRecipe);
 600
 601 public:
 602
 603   /**
 604    * Signal the start of a new round of assertion preprocessing
 605    */
 606   void preprocessStart();
 607
 608   /**
 609    * Runs theory specific preprocessing on the non-Boolean parts of
 610    * the formula.  This is only called on input assertions, after ITEs
 611    * have been removed.
 612    */
 613   Node preprocess(TNode node);
 614
 615   /** Notify (preprocessed) assertions. */
 616   void notifyPreprocessedAssertions(const std::vector<Node>& assertions);
 617
 618   /** Return whether or not we are incomplete (in the current context). */
 619   inline bool isIncomplete() const { return d_incomplete; }
 620
 621   /**
 622    * Returns true if we need another round of checking.  If this
 623    * returns true, check(FULL_EFFORT) _must_ be called by the
 624    * propositional layer before reporting SAT.
 625    *
 626    * This is especially necessary for incomplete theories that lazily
 627    * output some lemmas on FULL_EFFORT check (e.g. quantifier reasoning
 628    * outputing quantifier instantiations).  In such a case, a lemma can
 629    * be asserted that is simplified away (perhaps it's already true).
 630    * However, we must maintain the invariant that, if a theory uses the
 631    * OutputChannel, it implicitly requests that another check(FULL_EFFORT)
 632    * be performed before exit, even if no new facts are on its fact queue,
 633    * as it might decide to further instantiate some lemmas, precluding
 634    * a SAT response.
 635    */
 636   inline bool needCheck() const {
 637     return d_outputChannelUsed || d_lemmasAdded;
 638   }
 639
 640   /**
 641    * This is called at shutdown time by the SmtEngine, just before
 642    * destruction.  It is important because there are destruction
 643    * ordering issues between PropEngine and Theory.
 644    */
 645   void shutdown();
 646
 647   /**
 648    * Solve the given literal with a theory that owns it.
 649    */
 650   theory::Theory::PPAssertStatus solve(TNode literal,
 651                                     theory::SubstitutionMap& substitutionOut);
 652
 653   /**
 654    * Preregister a Theory atom with the responsible theory (or
 655    * theories).
 656    */
 657   void preRegister(TNode preprocessed);
 658
 659   /**
 660    * Assert the formula to the appropriate theory.
 661    * @param node the assertion
 662    */
 663   void assertFact(TNode node);
 664
 665   /**
 666    * Check all (currently-active) theories for conflicts.
 667    * @param effort the effort level to use
 668    */
 669   void check(theory::Theory::Effort effort);
 670
 671   /**
 672    * Run the combination framework.
 673    */
 674   void combineTheories();
 675
 676   /**
 677    * Calls ppStaticLearn() on all theories, accumulating their
 678    * combined contributions in the "learned" builder.
 679    */
 680   void ppStaticLearn(TNode in, NodeBuilder<>& learned);
 681
 682   /**
 683    * Calls presolve() on all theories and returns true
 684    * if one of the theories discovers a conflict.
 685    */
 686   bool presolve();
 687
 688    /**
 689    * Calls postsolve() on all theories.
 690    */
 691   void postsolve();
 692
 693   /**
 694    * Calls notifyRestart() on all active theories.
 695    */
 696   void notifyRestart();
 697
 698   void getPropagatedLiterals(std::vector<TNode>& literals) {
 699     for (; d_propagatedLiteralsIndex < d_propagatedLiterals.size(); d_propagatedLiteralsIndex = d_propagatedLiteralsIndex + 1) {
 700       Debug("getPropagatedLiterals") << "TheoryEngine::getPropagatedLiterals: propagating: " << d_propagatedLiterals[d_propagatedLiteralsIndex] << std::endl;
 701       literals.push_back(d_propagatedLiterals[d_propagatedLiteralsIndex]);
 702     }
 703   }
 704
 705   Node getNextDecisionRequest();
 706
 707   bool properConflict(TNode conflict) const;
 708   bool properPropagation(TNode lit) const;
 709   bool properExplanation(TNode node, TNode expl) const;
 710
 711   /**
 712    * Returns an explanation of the node propagated to the SAT solver.
 713    */
 714   Node getExplanation(TNode node);
 715
 716   /**
 717    * Returns an explanation of the node propagated to the SAT solver and the theory
 718    * that propagated it.
 719    */
 720   Node getExplanationAndRecipe(TNode node, LemmaProofRecipe* proofRecipe);
 721
 722   /**
 723    * collect model info
 724    */
 725   bool collectModelInfo(theory::TheoryModel* m);
 726   /** post process model */
 727   void postProcessModel( theory::TheoryModel* m );
 728
 729   /**
 730    * Get the current model
 731    */
 732   theory::TheoryModel* getModel();
 733
 734   /** get synth solutions
 735    *
 736    * This function adds entries to sol_map that map functions-to-synthesize with
 737    * their solutions, for all active conjectures. This should be called
 738    * immediately after the solver answers unsat for sygus input.
 739    *
 740    * For details on what is added to sol_map, see
 741    * CegConjecture::getSynthSolutions.
 742    */
 743   void getSynthSolutions(std::map<Node, Node>& sol_map);
 744
 745   /**
 746    * Get the model builder
 747    */
 748   theory::TheoryEngineModelBuilder* getModelBuilder() { return d_curr_model_builder; }
 749
 750   /**
 751    * Get the theory associated to a given Node.
 752    *
 753    * @returns the theory, or NULL if the TNode is
 754    * of built-in type.
 755    */
 756   inline theory::Theory* theoryOf(TNode node) const {
 757     return d_theoryTable[theory::Theory::theoryOf(node)];
 758   }
 759
 760   /**
 761    * Get the theory associated to a the given theory id.
 762    *
 763    * @returns the theory
 764    */
 765   inline theory::Theory* theoryOf(theory::TheoryId theoryId) const {
 766     return d_theoryTable[theoryId];
 767   }
 768
 769   inline bool isTheoryEnabled(theory::TheoryId theoryId) const {
 770     return d_logicInfo.isTheoryEnabled(theoryId);
 771   }
 772   /** get the logic info used by this theory engine */
 773   const LogicInfo& getLogicInfo() const;
 774   /**
 775    * Returns the equality status of the two terms, from the theory
 776    * that owns the domain type.  The types of a and b must be the same.
 777    */
 778   theory::EqualityStatus getEqualityStatus(TNode a, TNode b);
 779
 780   /**
 781    * Returns the value that a theory that owns the type of var currently
 782    * has (or null if none);
 783    */
 784   Node getModelValue(TNode var);
 785
 786   /**
 787    * Takes a literal and returns an equivalent literal that is guaranteed to be a SAT literal
 788    */
 789   Node ensureLiteral(TNode n);
 790
 791   /**
 792    * Print all instantiations made by the quantifiers module.
 793    */
 794   void printInstantiations( std::ostream& out );
 795
 796   /**
 797    * Print solution for synthesis conjectures found by ce_guided_instantiation module
 798    */
 799   void printSynthSolution( std::ostream& out );
 800
 801   /**
 802    * Get list of quantified formulas that were instantiated
 803    */
 804   void getInstantiatedQuantifiedFormulas( std::vector< Node >& qs );
 805
 806   /**
 807    * Get instantiation methods
 808    *   first inputs forall x.q[x] and returns ( q[a], ..., q[z] )
 809    *   second inputs forall x.q[x] and returns ( a, ..., z )
 810    *   third and fourth return mappings e.g. forall x.q1[x] -> ( q1[a]...q1[z] ) , ... , forall x.qn[x] -> ( qn[a]...qn[z] )
 811    */
 812   void getInstantiations( Node q, std::vector< Node >& insts );
 813   void getInstantiationTermVectors( Node q, std::vector< std::vector< Node > >& tvecs );
 814   void getInstantiations( std::map< Node, std::vector< Node > >& insts );
 815   void getInstantiationTermVectors( std::map< Node, std::vector< std::vector< Node > > >& insts );
 816
 817   /**
 818    * Get instantiated conjunction, returns q[t1] ^ ... ^ q[tn] where t1...tn are current set of instantiations for q.
 819    *   Can be used for quantifier elimination when satisfiable and q[t1] ^ ... ^ q[tn] |= q
 820    */
 821   Node getInstantiatedConjunction( Node q );
 822
 823   /**
 824    * Forwards an entailment check according to the given theoryOfMode.
 825    * See theory.h for documentation on entailmentCheck().
 826    */
 827   std::pair<bool, Node> entailmentCheck(theory::TheoryOfMode mode, TNode lit, const theory::EntailmentCheckParameters* params = NULL, theory::EntailmentCheckSideEffects* out = NULL);
 828
 829 private:
 830
 831   /** Default visitor for pre-registration */
 832   PreRegisterVisitor d_preRegistrationVisitor;
 833
 834   /** Visitor for collecting shared terms */
 835   SharedTermsVisitor d_sharedTermsVisitor;
 836
 837   /** Dump the assertions to the dump */
 838   void dumpAssertions(const char* tag);
 839
 840   /** For preprocessing pass lifting bit-vectors of size 1 to booleans */
 841 public:
 842   void staticInitializeBVOptions(const std::vector<Node>& assertions);
 843
 844   Node ppSimpITE(TNode assertion);
 845   /** Returns false if an assertion simplified to false. */
 846   bool donePPSimpITE(std::vector<Node>& assertions);
 847
 848   SharedTermsDatabase* getSharedTermsDatabase() { return &d_sharedTerms; }
 849
 850   theory::eq::EqualityEngine* getMasterEqualityEngine() { return d_masterEqualityEngine; }
 851
 852   RemoveTermFormulas* getTermFormulaRemover() { return &d_tform_remover; }
 853
 854   SortInference* getSortInference() { return &d_sortInfer; }
 855
 856   /** Prints the assertions to the debug stream */
 857   void printAssertions(const char* tag);
 858
 859   /** Theory alternative is in use. */
 860   bool useTheoryAlternative(const std::string& name);
 861
 862   /** Enables using a theory alternative by name. */
 863   void enableTheoryAlternative(const std::string& name);
 864
 865 private:
 866   std::set< std::string > d_theoryAlternatives;
 867
 868   std::map< std::string, std::vector< theory::Theory* > > d_attr_handle;
 869
 870  public:
 871   /** Set user attribute.
 872    *
 873    * This function is called when an attribute is set by a user.  In SMT-LIBv2
 874    * this is done via the syntax (! n :attr)
 875    */
 876   void setUserAttribute(const std::string& attr,
 877                         Node n,
 878                         const std::vector<Node>& node_values,
 879                         const std::string& str_value);
 880
 881   /** Handle user attribute.
 882    *
 883    * Associates theory t with the attribute attr.  Theory t will be
 884    * notified whenever an attribute of name attr is set.
 885    */
 886   void handleUserAttribute(const char* attr, theory::Theory* t);
 887
 888   /**
 889    * Check that the theory assertions are satisfied in the model.
 890    * This function is called from the smt engine's checkModel routine.
 891    */
 892   void checkTheoryAssertionsWithModel(bool hardFailure);
 893
 894  private:
 895   IntStat d_arithSubstitutionsAdded;
 896
 897 };/* class TheoryEngine */
 898
 899 }/* CVC4 namespace */
 900
 901 #endif /* __CVC4__THEORY_ENGINE_H */