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