src/theory/theory_engine.h

   1 /*********************                                                        */
   2 /*! \file theory_engine.h
   3  ** \verbatim
   4  ** Top contributors (to current version):
   5  **   Morgan Deters, Dejan Jovanovic, Andrew Reynolds
   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 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/bv/bv_to_bool.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   class ITEUtilities;
  89
  90   namespace eq {
  91     class EqualityEngine;
  92   }/* CVC4::theory::eq namespace */
  93
  94   namespace quantifiers {
  95     class TermDb;
  96   }
  97
  98   class EntailmentCheckParameters;
  99   class EntailmentCheckSideEffects;
 100 }/* CVC4::theory namespace */
 101
 102 class DecisionEngine;
 103 class RemoveTermFormulas;
 104 class UnconstrainedSimplifier;
 105
 106 /**
 107  * This is essentially an abstraction for a collection of theories.  A
 108  * TheoryEngine provides services to a PropEngine, making various
 109  * T-solvers look like a single unit to the propositional part of
 110  * CVC4.
 111  */
 112 class TheoryEngine {
 113
 114   /** Shared terms database can use the internals notify the theories */
 115   friend class SharedTermsDatabase;
 116   friend class theory::quantifiers::TermDb;
 117
 118   /** Associated PropEngine engine */
 119   prop::PropEngine* d_propEngine;
 120
 121   /** Access to decision engine */
 122   DecisionEngine* d_decisionEngine;
 123
 124   /** Our context */
 125   context::Context* d_context;
 126
 127   /** Our user context */
 128   context::UserContext* d_userContext;
 129
 130   /**
 131    * A table of from theory IDs to theory pointers. Never use this table
 132    * directly, use theoryOf() instead.
 133    */
 134   theory::Theory* d_theoryTable[theory::THEORY_LAST];
 135
 136   /**
 137    * A collection of theories that are "active" for the current run.
 138    * This set is provided by the user (as a logic string, say, in SMT-LIBv2
 139    * format input), or else by default it's all-inclusive.  This is important
 140    * because we can optimize for single-theory runs (no sharing), can reduce
 141    * the cost of walking the DAG on registration, etc.
 142    */
 143   const LogicInfo& d_logicInfo;
 144
 145   /**
 146    * The database of shared terms.
 147    */
 148   SharedTermsDatabase d_sharedTerms;
 149
 150   /**
 151    * Master equality engine, to share with theories.
 152    */
 153   theory::eq::EqualityEngine* d_masterEqualityEngine;
 154
 155   /** notify class for master equality engine */
 156   class NotifyClass : public theory::eq::EqualityEngineNotify {
 157     TheoryEngine& d_te;
 158   public:
 159     NotifyClass(TheoryEngine& te): d_te(te) {}
 160     bool eqNotifyTriggerEquality(TNode equality, bool value) override
 161     {
 162       return true;
 163     }
 164     bool eqNotifyTriggerPredicate(TNode predicate, bool value) override
 165     {
 166       return true;
 167     }
 168     bool eqNotifyTriggerTermEquality(theory::TheoryId tag,
 169                                      TNode t1,
 170                                      TNode t2,
 171                                      bool value) override
 172     {
 173       return true;
 174     }
 175     void eqNotifyConstantTermMerge(TNode t1, TNode t2) override {}
 176     void eqNotifyNewClass(TNode t) override { d_te.eqNotifyNewClass(t); }
 177     void eqNotifyPreMerge(TNode t1, TNode t2) override
 178     {
 179       d_te.eqNotifyPreMerge(t1, t2);
 180     }
 181     void eqNotifyPostMerge(TNode t1, TNode t2) override
 182     {
 183       d_te.eqNotifyPostMerge(t1, t2);
 184     }
 185     void eqNotifyDisequal(TNode t1, TNode t2, TNode reason) override
 186     {
 187       d_te.eqNotifyDisequal(t1, t2, reason);
 188     }
 189   };/* class TheoryEngine::NotifyClass */
 190   NotifyClass d_masterEENotify;
 191
 192   /**
 193    * notification methods
 194    */
 195   void eqNotifyNewClass(TNode t);
 196   void eqNotifyPreMerge(TNode t1, TNode t2);
 197   void eqNotifyPostMerge(TNode t1, TNode t2);
 198   void eqNotifyDisequal(TNode t1, TNode t2, TNode reason);
 199
 200   /**
 201    * The quantifiers engine
 202    */
 203   theory::QuantifiersEngine* d_quantEngine;
 204
 205   /**
 206    * Default model object
 207    */
 208   theory::TheoryModel* d_curr_model;
 209   bool d_aloc_curr_model;
 210   /**
 211    * Model builder object
 212    */
 213   theory::TheoryEngineModelBuilder* d_curr_model_builder;
 214   bool d_aloc_curr_model_builder;
 215
 216   typedef std::unordered_map<Node, Node, NodeHashFunction> NodeMap;
 217   typedef std::unordered_map<TNode, Node, TNodeHashFunction> TNodeMap;
 218
 219   /**
 220   * Cache for theory-preprocessing of assertions
 221    */
 222   NodeMap d_ppCache;
 223
 224   /**
 225    * Used for "missed-t-propagations" dumping mode only.  A set of all
 226    * theory-propagable literals.
 227    */
 228   context::CDList<TNode> d_possiblePropagations;
 229
 230   /**
 231    * Used for "missed-t-propagations" dumping mode only.  A
 232    * context-dependent set of those theory-propagable literals that
 233    * have been propagated.
 234    */
 235   context::CDHashSet<Node, NodeHashFunction> d_hasPropagated;
 236
 237
 238   /**
 239    * Statistics for a particular theory.
 240    */
 241   class Statistics {
 242
 243     static std::string mkName(std::string prefix,
 244                               theory::TheoryId theory,
 245                               std::string suffix) {
 246       std::stringstream ss;
 247       ss << prefix << theory << suffix;
 248       return ss.str();
 249     }
 250
 251   public:
 252
 253     IntStat conflicts, propagations, lemmas, requirePhase, flipDecision, restartDemands;
 254
 255     Statistics(theory::TheoryId theory);
 256     ~Statistics();
 257   };/* class TheoryEngine::Statistics */
 258
 259   /**
 260    * An output channel for Theory that passes messages
 261    * back to a TheoryEngine.
 262    */
 263   class EngineOutputChannel : public theory::OutputChannel {
 264     friend class TheoryEngine;
 265
 266     /**
 267      * The theory engine we're communicating with.
 268      */
 269     TheoryEngine* d_engine;
 270
 271     /**
 272      * The statistics of the theory interractions.
 273      */
 274     Statistics d_statistics;
 275
 276     /** The theory owning this channel. */
 277     theory::TheoryId d_theory;
 278
 279    public:
 280     EngineOutputChannel(TheoryEngine* engine, theory::TheoryId theory)
 281         : d_engine(engine), d_statistics(theory), d_theory(theory) {}
 282
 283     void safePoint(uint64_t amount) override {
 284       spendResource(amount);
 285       if (d_engine->d_interrupted) {
 286         throw theory::Interrupted();
 287       }
 288     }
 289
 290     void conflict(TNode conflictNode,
 291                   std::unique_ptr<Proof> pf = nullptr) override;
 292     bool propagate(TNode literal) override;
 293
 294     theory::LemmaStatus lemma(TNode lemma, ProofRule rule,
 295                               bool removable = false, bool preprocess = false,
 296                               bool sendAtoms = false) override;
 297
 298     theory::LemmaStatus splitLemma(TNode lemma,
 299                                    bool removable = false) override;
 300
 301     void demandRestart() override {
 302       NodeManager* curr = NodeManager::currentNM();
 303       Node restartVar = curr->mkSkolem(
 304           "restartVar", curr->booleanType(),
 305           "A boolean variable asserted to be true to force a restart");
 306       Trace("theory::restart")
 307           << "EngineOutputChannel<" << d_theory << ">::restart(" << restartVar
 308           << ")" << std::endl;
 309       ++d_statistics.restartDemands;
 310       lemma(restartVar, RULE_INVALID, true);
 311     }
 312
 313     void requirePhase(TNode n, bool phase) override {
 314       Debug("theory") << "EngineOutputChannel::requirePhase(" << n << ", "
 315                       << phase << ")" << std::endl;
 316       ++d_statistics.requirePhase;
 317       d_engine->d_propEngine->requirePhase(n, phase);
 318     }
 319
 320     bool flipDecision() override {
 321       Debug("theory") << "EngineOutputChannel::flipDecision()" << std::endl;
 322       ++d_statistics.flipDecision;
 323       return d_engine->d_propEngine->flipDecision();
 324     }
 325
 326     void setIncomplete() override {
 327       Trace("theory") << "TheoryEngine::setIncomplete()" << std::endl;
 328       d_engine->setIncomplete(d_theory);
 329     }
 330
 331     void spendResource(unsigned amount) override {
 332       d_engine->spendResource(amount);
 333     }
 334
 335     void handleUserAttribute(const char* attr, theory::Theory* t) override {
 336       d_engine->handleUserAttribute(attr, t);
 337     }
 338
 339    private:
 340     /**
 341      * A helper function for registering lemma recipes with the proof engine
 342      */
 343     void registerLemmaRecipe(Node lemma, Node originalLemma, bool preprocess,
 344                              theory::TheoryId theoryId);
 345   }; /* class TheoryEngine::EngineOutputChannel */
 346
 347   /**
 348    * Output channels for individual theories.
 349    */
 350   EngineOutputChannel* d_theoryOut[theory::THEORY_LAST];
 351
 352   /**
 353    * Are we in conflict.
 354    */
 355   context::CDO<bool> d_inConflict;
 356
 357   /**
 358    * Called by the theories to notify of a conflict.
 359    */
 360   void conflict(TNode conflict, theory::TheoryId theoryId);
 361
 362   /**
 363    * Debugging flag to ensure that shutdown() is called before the
 364    * destructor.
 365    */
 366   bool d_hasShutDown;
 367
 368   /**
 369    * True if a theory has notified us of incompleteness (at this
 370    * context level or below).
 371    */
 372   context::CDO<bool> d_incomplete;
 373
 374   /**
 375    * Called by the theories to notify that the current branch is incomplete.
 376    */
 377   void setIncomplete(theory::TheoryId theory) {
 378     d_incomplete = true;
 379   }
 380
 381
 382   /**
 383    * Mapping of propagations from recievers to senders.
 384    */
 385   typedef context::CDHashMap<NodeTheoryPair, NodeTheoryPair, NodeTheoryPairHashFunction> PropagationMap;
 386   PropagationMap d_propagationMap;
 387
 388   /**
 389    * Timestamp of propagations
 390    */
 391   context::CDO<size_t> d_propagationMapTimestamp;
 392
 393   /**
 394    * Literals that are propagated by the theory. Note that these are TNodes.
 395    * The theory can only propagate nodes that have an assigned literal in the
 396    * SAT solver and are hence referenced in the SAT solver.
 397    */
 398   context::CDList<TNode> d_propagatedLiterals;
 399
 400   /**
 401    * The index of the next literal to be propagated by a theory.
 402    */
 403   context::CDO<unsigned> d_propagatedLiteralsIndex;
 404
 405   /**
 406    * Called by the output channel to propagate literals and facts
 407    * @return false if immediate conflict
 408    */
 409   bool propagate(TNode literal, theory::TheoryId theory);
 410
 411   /**
 412    * Internal method to call the propagation routines and collect the
 413    * propagated literals.
 414    */
 415   void propagate(theory::Theory::Effort effort);
 416
 417   /**
 418    * Called by the output channel to request decisions "as soon as
 419    * possible."
 420    */
 421   void propagateAsDecision(TNode literal, theory::TheoryId theory);
 422
 423   /**
 424    * A variable to mark if we added any lemmas.
 425    */
 426   bool d_lemmasAdded;
 427
 428   /**
 429    * A variable to mark if the OutputChannel was "used" by any theory
 430    * since the start of the last check.  If it has been, we require
 431    * a FULL_EFFORT check before exiting and reporting SAT.
 432    *
 433    * See the documentation for the needCheck() function, below.
 434    */
 435   bool d_outputChannelUsed;
 436
 437   /** Atom requests from lemmas */
 438   AtomRequests d_atomRequests;
 439
 440   /**
 441    * Adds a new lemma, returning its status.
 442    * @param node the lemma
 443    * @param negated should the lemma be asserted negated
 444    * @param removable can the lemma be remove (restrictions apply)
 445    * @param needAtoms if not THEORY_LAST, then
 446    */
 447   theory::LemmaStatus lemma(TNode node,
 448                             ProofRule rule,
 449                             bool negated,
 450                             bool removable,
 451                             bool preprocess,
 452                             theory::TheoryId atomsTo);
 453
 454   /** Enusre that the given atoms are send to the given theory */
 455   void ensureLemmaAtoms(const std::vector<TNode>& atoms, theory::TheoryId theory);
 456
 457   RemoveTermFormulas& d_tform_remover;
 458
 459   /** sort inference module */
 460   SortInference d_sortInfer;
 461
 462   /** Time spent in theory combination */
 463   TimerStat d_combineTheoriesTime;
 464
 465   Node d_true;
 466   Node d_false;
 467
 468   /** Whether we were just interrupted (or not) */
 469   bool d_interrupted;
 470   ResourceManager* d_resourceManager;
 471
 472   /** Container for lemma input and output channels. */
 473   LemmaChannels* d_channels;
 474
 475 public:
 476
 477   /** Constructs a theory engine */
 478   TheoryEngine(context::Context* context, context::UserContext* userContext,
 479                RemoveTermFormulas& iteRemover, const LogicInfo& logic,
 480                LemmaChannels* channels);
 481
 482   /** Destroys a theory engine */
 483   ~TheoryEngine();
 484
 485   void interrupt();
 486
 487   /** "Spend" a resource during a search or preprocessing.*/
 488   void spendResource(unsigned amount);
 489
 490   /**
 491    * Adds a theory. Only one theory per TheoryId can be present, so if
 492    * there is another theory it will be deleted.
 493    */
 494   template <class TheoryClass>
 495   inline void addTheory(theory::TheoryId theoryId) {
 496     Assert(d_theoryTable[theoryId] == NULL && d_theoryOut[theoryId] == NULL);
 497     d_theoryOut[theoryId] = new EngineOutputChannel(this, theoryId);
 498     d_theoryTable[theoryId] =
 499         new TheoryClass(d_context, d_userContext, *d_theoryOut[theoryId],
 500                         theory::Valuation(this), d_logicInfo);
 501   }
 502
 503   inline void setPropEngine(prop::PropEngine* propEngine) {
 504     Assert(d_propEngine == NULL);
 505     d_propEngine = propEngine;
 506   }
 507
 508   inline void setDecisionEngine(DecisionEngine* decisionEngine) {
 509     Assert(d_decisionEngine == NULL);
 510     d_decisionEngine = decisionEngine;
 511   }
 512
 513   /** Called when all initialization of options/logic is done */
 514   void finishInit();
 515
 516   /**
 517    * Get a pointer to the underlying propositional engine.
 518    */
 519   inline prop::PropEngine* getPropEngine() const {
 520     return d_propEngine;
 521   }
 522
 523   /**
 524    * Get a pointer to the underlying sat context.
 525    */
 526   inline context::Context* getSatContext() const {
 527     return d_context;
 528   }
 529
 530   /**
 531    * Get a pointer to the underlying user context.
 532    */
 533   inline context::Context* getUserContext() const {
 534     return d_userContext;
 535   }
 536
 537   /**
 538    * Get a pointer to the underlying quantifiers engine.
 539    */
 540   theory::QuantifiersEngine* getQuantifiersEngine() const {
 541     return d_quantEngine;
 542   }
 543
 544 private:
 545
 546   /**
 547    * Helper for preprocess
 548    */
 549   Node ppTheoryRewrite(TNode term);
 550
 551   /**
 552    * Queue of nodes for pre-registration.
 553    */
 554   std::queue<TNode> d_preregisterQueue;
 555
 556   /**
 557    * Boolean flag denoting we are in pre-registration.
 558    */
 559   bool d_inPreregister;
 560
 561   /**
 562    * Did the theories get any new facts since the last time we called
 563    * check()
 564    */
 565   context::CDO<bool> d_factsAsserted;
 566
 567   /**
 568    * Map from equality atoms to theories that would like to be notified about them.
 569    */
 570
 571
 572   /**
 573    * Assert the formula to the given theory.
 574    * @param assertion the assertion to send (not necesserily normalized)
 575    * @param original the assertion as it was sent in from the propagating theory
 576    * @param toTheoryId the theory to assert to
 577    * @param fromTheoryId the theory that sent it
 578    */
 579   void assertToTheory(TNode assertion, TNode originalAssertion, theory::TheoryId toTheoryId, theory::TheoryId fromTheoryId);
 580
 581   /**
 582    * Marks a theory propagation from a theory to a theory where a
 583    * theory could be the THEORY_SAT_SOLVER for literals coming from
 584    * or being propagated to the SAT solver. If the receiving theory
 585    * already recieved the literal, the method returns false, otherwise
 586    * it returns true.
 587    *
 588    * @param assertion the normalized assertion being sent
 589    * @param originalAssertion the actual assertion that was sent
 590    * @param toTheoryId the theory that is on the receiving end
 591    * @param fromTheoryId the theory that sent the assertino
 592    * @return true if a new assertion, false if theory already got it
 593    */
 594   bool markPropagation(TNode assertion, TNode originalAssertions, theory::TheoryId toTheoryId, theory::TheoryId fromTheoryId);
 595
 596   /**
 597    * Computes the explanation by travarsing the propagation graph and
 598    * asking relevant theories to explain the propagations. Initially
 599    * the explanation vector should contain only the element (node, theory)
 600    * where the node is the one to be explained, and the theory is the
 601    * theory that sent the literal. The lemmaProofRecipe will contain a list
 602    * of the explanation steps required to produce the original node.
 603    */
 604   void getExplanation(std::vector<NodeTheoryPair>& explanationVector, LemmaProofRecipe* lemmaProofRecipe);
 605
 606 public:
 607
 608   /**
 609    * Signal the start of a new round of assertion preprocessing
 610    */
 611   void preprocessStart();
 612
 613   /**
 614    * Runs theory specific preprocessing on the non-Boolean parts of
 615    * the formula.  This is only called on input assertions, after ITEs
 616    * have been removed.
 617    */
 618   Node preprocess(TNode node);
 619
 620   /** Notify (preprocessed) assertions. */
 621   void notifyPreprocessedAssertions(const std::vector<Node>& assertions);
 622
 623   /** Return whether or not we are incomplete (in the current context). */
 624   inline bool isIncomplete() const { return d_incomplete; }
 625
 626   /**
 627    * Returns true if we need another round of checking.  If this
 628    * returns true, check(FULL_EFFORT) _must_ be called by the
 629    * propositional layer before reporting SAT.
 630    *
 631    * This is especially necessary for incomplete theories that lazily
 632    * output some lemmas on FULL_EFFORT check (e.g. quantifier reasoning
 633    * outputing quantifier instantiations).  In such a case, a lemma can
 634    * be asserted that is simplified away (perhaps it's already true).
 635    * However, we must maintain the invariant that, if a theory uses the
 636    * OutputChannel, it implicitly requests that another check(FULL_EFFORT)
 637    * be performed before exit, even if no new facts are on its fact queue,
 638    * as it might decide to further instantiate some lemmas, precluding
 639    * a SAT response.
 640    */
 641   inline bool needCheck() const {
 642     return d_outputChannelUsed || d_lemmasAdded;
 643   }
 644
 645   /**
 646    * This is called at shutdown time by the SmtEngine, just before
 647    * destruction.  It is important because there are destruction
 648    * ordering issues between PropEngine and Theory.
 649    */
 650   void shutdown();
 651
 652   /**
 653    * Solve the given literal with a theory that owns it.
 654    */
 655   theory::Theory::PPAssertStatus solve(TNode literal,
 656                                     theory::SubstitutionMap& substitutionOut);
 657
 658   /**
 659    * Preregister a Theory atom with the responsible theory (or
 660    * theories).
 661    */
 662   void preRegister(TNode preprocessed);
 663
 664   /**
 665    * Assert the formula to the appropriate theory.
 666    * @param node the assertion
 667    */
 668   void assertFact(TNode node);
 669
 670   /**
 671    * Check all (currently-active) theories for conflicts.
 672    * @param effort the effort level to use
 673    */
 674   void check(theory::Theory::Effort effort);
 675
 676   /**
 677    * Run the combination framework.
 678    */
 679   void combineTheories();
 680
 681   /**
 682    * Calls ppStaticLearn() on all theories, accumulating their
 683    * combined contributions in the "learned" builder.
 684    */
 685   void ppStaticLearn(TNode in, NodeBuilder<>& learned);
 686
 687   /**
 688    * Calls presolve() on all theories and returns true
 689    * if one of the theories discovers a conflict.
 690    */
 691   bool presolve();
 692
 693    /**
 694    * Calls postsolve() on all theories.
 695    */
 696   void postsolve();
 697
 698   /**
 699    * Calls notifyRestart() on all active theories.
 700    */
 701   void notifyRestart();
 702
 703   void getPropagatedLiterals(std::vector<TNode>& literals) {
 704     for (; d_propagatedLiteralsIndex < d_propagatedLiterals.size(); d_propagatedLiteralsIndex = d_propagatedLiteralsIndex + 1) {
 705       Debug("getPropagatedLiterals") << "TheoryEngine::getPropagatedLiterals: propagating: " << d_propagatedLiterals[d_propagatedLiteralsIndex] << std::endl;
 706       literals.push_back(d_propagatedLiterals[d_propagatedLiteralsIndex]);
 707     }
 708   }
 709
 710   Node getNextDecisionRequest();
 711
 712   bool properConflict(TNode conflict) const;
 713   bool properPropagation(TNode lit) const;
 714   bool properExplanation(TNode node, TNode expl) const;
 715
 716   /**
 717    * Returns an explanation of the node propagated to the SAT solver.
 718    */
 719   Node getExplanation(TNode node);
 720
 721   /**
 722    * Returns an explanation of the node propagated to the SAT solver and the theory
 723    * that propagated it.
 724    */
 725   Node getExplanationAndRecipe(TNode node, LemmaProofRecipe* proofRecipe);
 726
 727   /**
 728    * collect model info
 729    */
 730   bool collectModelInfo(theory::TheoryModel* m);
 731   /** post process model */
 732   void postProcessModel( theory::TheoryModel* m );
 733
 734   /**
 735    * Get the current model
 736    */
 737   theory::TheoryModel* getModel();
 738
 739   /** get synth solutions
 740    *
 741    * This function adds entries to sol_map that map functions-to-synthesize with
 742    * their solutions, for all active conjectures. This should be called
 743    * immediately after the solver answers unsat for sygus input.
 744    *
 745    * For details on what is added to sol_map, see
 746    * CegConjecture::getSynthSolutions.
 747    */
 748   void getSynthSolutions(std::map<Node, Node>& sol_map);
 749
 750   /**
 751    * Get the model builder
 752    */
 753   theory::TheoryEngineModelBuilder* getModelBuilder() { return d_curr_model_builder; }
 754
 755   /**
 756    * Get the theory associated to a given Node.
 757    *
 758    * @returns the theory, or NULL if the TNode is
 759    * of built-in type.
 760    */
 761   inline theory::Theory* theoryOf(TNode node) const {
 762     return d_theoryTable[theory::Theory::theoryOf(node)];
 763   }
 764
 765   /**
 766    * Get the theory associated to a the given theory id.
 767    *
 768    * @returns the theory
 769    */
 770   inline theory::Theory* theoryOf(theory::TheoryId theoryId) const {
 771     return d_theoryTable[theoryId];
 772   }
 773
 774   inline bool isTheoryEnabled(theory::TheoryId theoryId) const {
 775     return d_logicInfo.isTheoryEnabled(theoryId);
 776   }
 777
 778   /**
 779    * Returns the equality status of the two terms, from the theory
 780    * that owns the domain type.  The types of a and b must be the same.
 781    */
 782   theory::EqualityStatus getEqualityStatus(TNode a, TNode b);
 783
 784   /**
 785    * Returns the value that a theory that owns the type of var currently
 786    * has (or null if none);
 787    */
 788   Node getModelValue(TNode var);
 789
 790   /**
 791    * Takes a literal and returns an equivalent literal that is guaranteed to be a SAT literal
 792    */
 793   Node ensureLiteral(TNode n);
 794
 795   /**
 796    * Print all instantiations made by the quantifiers module.
 797    */
 798   void printInstantiations( std::ostream& out );
 799
 800   /**
 801    * Print solution for synthesis conjectures found by ce_guided_instantiation module
 802    */
 803   void printSynthSolution( std::ostream& out );
 804
 805   /**
 806    * Get list of quantified formulas that were instantiated
 807    */
 808   void getInstantiatedQuantifiedFormulas( std::vector< Node >& qs );
 809
 810   /**
 811    * Get instantiation methods
 812    *   first inputs forall x.q[x] and returns ( q[a], ..., q[z] )
 813    *   second inputs forall x.q[x] and returns ( a, ..., z )
 814    *   third and fourth return mappings e.g. forall x.q1[x] -> ( q1[a]...q1[z] ) , ... , forall x.qn[x] -> ( qn[a]...qn[z] )
 815    */
 816   void getInstantiations( Node q, std::vector< Node >& insts );
 817   void getInstantiationTermVectors( Node q, std::vector< std::vector< Node > >& tvecs );
 818   void getInstantiations( std::map< Node, std::vector< Node > >& insts );
 819   void getInstantiationTermVectors( std::map< Node, std::vector< std::vector< Node > > >& insts );
 820
 821   /**
 822    * Get instantiated conjunction, returns q[t1] ^ ... ^ q[tn] where t1...tn are current set of instantiations for q.
 823    *   Can be used for quantifier elimination when satisfiable and q[t1] ^ ... ^ q[tn] |= q
 824    */
 825   Node getInstantiatedConjunction( Node q );
 826
 827   /**
 828    * Forwards an entailment check according to the given theoryOfMode.
 829    * See theory.h for documentation on entailmentCheck().
 830    */
 831   std::pair<bool, Node> entailmentCheck(theory::TheoryOfMode mode, TNode lit, const theory::EntailmentCheckParameters* params = NULL, theory::EntailmentCheckSideEffects* out = NULL);
 832
 833 private:
 834
 835   /** Default visitor for pre-registration */
 836   PreRegisterVisitor d_preRegistrationVisitor;
 837
 838   /** Visitor for collecting shared terms */
 839   SharedTermsVisitor d_sharedTermsVisitor;
 840
 841   /** Dump the assertions to the dump */
 842   void dumpAssertions(const char* tag);
 843
 844   /**
 845    * A collection of ite preprocessing passes.
 846    */
 847   theory::ITEUtilities* d_iteUtilities;
 848
 849
 850   /** For preprocessing pass simplifying unconstrained expressions */
 851   UnconstrainedSimplifier* d_unconstrainedSimp;
 852
 853   /** For preprocessing pass lifting bit-vectors of size 1 to booleans */
 854   theory::bv::BvToBoolPreprocessor d_bvToBoolPreprocessor;
 855 public:
 856   void staticInitializeBVOptions(const std::vector<Node>& assertions);
 857   void ppBvToBool(const std::vector<Node>& assertions, std::vector<Node>& new_assertions);
 858   void ppBoolToBv(const std::vector<Node>& assertions, std::vector<Node>& new_assertions);
 859   bool ppBvAbstraction(const std::vector<Node>& assertions, std::vector<Node>& new_assertions);
 860   void mkAckermanizationAssertions(std::vector<Node>& assertions);
 861
 862   Node ppSimpITE(TNode assertion);
 863   /** Returns false if an assertion simplified to false. */
 864   bool donePPSimpITE(std::vector<Node>& assertions);
 865
 866   void ppUnconstrainedSimp(std::vector<Node>& assertions);
 867
 868   SharedTermsDatabase* getSharedTermsDatabase() { return &d_sharedTerms; }
 869
 870   theory::eq::EqualityEngine* getMasterEqualityEngine() { return d_masterEqualityEngine; }
 871
 872   RemoveTermFormulas* getTermFormulaRemover() { return &d_tform_remover; }
 873
 874   SortInference* getSortInference() { return &d_sortInfer; }
 875
 876   /** Prints the assertions to the debug stream */
 877   void printAssertions(const char* tag);
 878
 879   /** Theory alternative is in use. */
 880   bool useTheoryAlternative(const std::string& name);
 881
 882   /** Enables using a theory alternative by name. */
 883   void enableTheoryAlternative(const std::string& name);
 884
 885 private:
 886   std::set< std::string > d_theoryAlternatives;
 887
 888   std::map< std::string, std::vector< theory::Theory* > > d_attr_handle;
 889
 890  public:
 891   /** Set user attribute.
 892    *
 893    * This function is called when an attribute is set by a user.  In SMT-LIBv2
 894    * this is done via the syntax (! n :attr)
 895    */
 896   void setUserAttribute(const std::string& attr,
 897                         Node n,
 898                         const std::vector<Node>& node_values,
 899                         const std::string& str_value);
 900
 901   /** Handle user attribute.
 902    *
 903    * Associates theory t with the attribute attr.  Theory t will be
 904    * notified whenever an attribute of name attr is set.
 905    */
 906   void handleUserAttribute(const char* attr, theory::Theory* t);
 907
 908   /**
 909    * Check that the theory assertions are satisfied in the model.
 910    * This function is called from the smt engine's checkModel routine.
 911    */
 912   void checkTheoryAssertionsWithModel(bool hardFailure);
 913
 914  private:
 915   IntStat d_arithSubstitutionsAdded;
 916
 917 };/* class TheoryEngine */
 918
 919 }/* CVC4 namespace */
 920
 921 #endif /* __CVC4__THEORY_ENGINE_H */