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/statistics_registry.h"
  48 #include "util/unsafe_interrupt_exception.h"
  49
  50 namespace CVC4 {
  51
  52 class ResourceManager;
  53 class LemmaProofRecipe;
  54
  55 /**
  56  * A pair of a theory and a node. This is used to mark the flow of
  57  * propagations between theories.
  58  */
  59 struct NodeTheoryPair {
  60   Node node;
  61   theory::TheoryId theory;
  62   size_t timestamp;
  63   NodeTheoryPair(TNode node, theory::TheoryId theory, size_t timestamp = 0)
  64   : node(node), theory(theory), timestamp(timestamp) {}
  65   NodeTheoryPair()
  66   : theory(theory::THEORY_LAST) {}
  67   // Comparison doesn't take into account the timestamp
  68   bool operator == (const NodeTheoryPair& pair) const {
  69     return node == pair.node && theory == pair.theory;
  70   }
  71 };/* struct NodeTheoryPair */
  72
  73 struct NodeTheoryPairHashFunction {
  74   NodeHashFunction hashFunction;
  75   // Hash doesn't take into account the timestamp
  76   size_t operator()(const NodeTheoryPair& pair) const {
  77     return hashFunction(pair.node)*0x9e3779b9 + pair.theory;
  78   }
  79 };/* struct NodeTheoryPairHashFunction */
  80
  81
  82 /* Forward declarations */
  83 namespace theory {
  84   class TheoryModel;
  85   class TheoryEngineModelBuilder;
  86   class ITEUtilities;
  87
  88   namespace eq {
  89     class EqualityEngine;
  90   }/* CVC4::theory::eq namespace */
  91
  92   namespace quantifiers {
  93     class TermDb;
  94   }
  95
  96   class EntailmentCheckParameters;
  97   class EntailmentCheckSideEffects;
  98 }/* CVC4::theory namespace */
  99
 100 class DecisionEngine;
 101 class RemoveTermFormulas;
 102 class UnconstrainedSimplifier;
 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) { return true; }
 159     bool eqNotifyTriggerPredicate(TNode predicate, bool value) { return true; }
 160     bool eqNotifyTriggerTermEquality(theory::TheoryId tag, TNode t1, TNode t2, bool value) { return true; }
 161     void eqNotifyConstantTermMerge(TNode t1, TNode t2) {}
 162     void eqNotifyNewClass(TNode t) { d_te.eqNotifyNewClass(t); }
 163     void eqNotifyPreMerge(TNode t1, TNode t2) { d_te.eqNotifyPreMerge(t1, t2); }
 164     void eqNotifyPostMerge(TNode t1, TNode t2) { d_te.eqNotifyPostMerge(t1, t2); }
 165     void eqNotifyDisequal(TNode t1, TNode t2, TNode reason) { d_te.eqNotifyDisequal(t1, t2, reason); }
 166   };/* class TheoryEngine::NotifyClass */
 167   NotifyClass d_masterEENotify;
 168
 169   /**
 170    * notification methods
 171    */
 172   void eqNotifyNewClass(TNode t);
 173   void eqNotifyPreMerge(TNode t1, TNode t2);
 174   void eqNotifyPostMerge(TNode t1, TNode t2);
 175   void eqNotifyDisequal(TNode t1, TNode t2, TNode reason);
 176
 177   /**
 178    * The quantifiers engine
 179    */
 180   theory::QuantifiersEngine* d_quantEngine;
 181
 182   /**
 183    * Default model object
 184    */
 185   theory::TheoryModel* d_curr_model;
 186   bool d_aloc_curr_model;
 187   /**
 188    * Model builder object
 189    */
 190   theory::TheoryEngineModelBuilder* d_curr_model_builder;
 191   bool d_aloc_curr_model_builder;
 192
 193   typedef std::unordered_map<Node, Node, NodeHashFunction> NodeMap;
 194   typedef std::unordered_map<TNode, Node, TNodeHashFunction> TNodeMap;
 195
 196   /**
 197   * Cache for theory-preprocessing of assertions
 198    */
 199   NodeMap d_ppCache;
 200
 201   /**
 202    * Used for "missed-t-propagations" dumping mode only.  A set of all
 203    * theory-propagable literals.
 204    */
 205   context::CDList<TNode> d_possiblePropagations;
 206
 207   /**
 208    * Used for "missed-t-propagations" dumping mode only.  A
 209    * context-dependent set of those theory-propagable literals that
 210    * have been propagated.
 211    */
 212   context::CDHashSet<Node, NodeHashFunction> d_hasPropagated;
 213
 214
 215   /**
 216    * Statistics for a particular theory.
 217    */
 218   class Statistics {
 219
 220     static std::string mkName(std::string prefix,
 221                               theory::TheoryId theory,
 222                               std::string suffix) {
 223       std::stringstream ss;
 224       ss << prefix << theory << suffix;
 225       return ss.str();
 226     }
 227
 228   public:
 229
 230     IntStat conflicts, propagations, lemmas, requirePhase, flipDecision, restartDemands;
 231
 232     Statistics(theory::TheoryId theory);
 233     ~Statistics();
 234   };/* class TheoryEngine::Statistics */
 235
 236
 237   /**
 238    * An output channel for Theory that passes messages
 239    * back to a TheoryEngine.
 240    */
 241   class EngineOutputChannel : public theory::OutputChannel {
 242
 243     friend class TheoryEngine;
 244
 245     /**
 246      * The theory engine we're communicating with.
 247      */
 248     TheoryEngine* d_engine;
 249
 250     /**
 251      * The statistics of the theory interractions.
 252      */
 253     Statistics d_statistics;
 254
 255     /**
 256      * The theory owning this chanell.
 257      */
 258     theory::TheoryId d_theory;
 259
 260   public:
 261
 262     EngineOutputChannel(TheoryEngine* engine, theory::TheoryId theory) :
 263       d_engine(engine),
 264       d_statistics(theory),
 265       d_theory(theory)
 266     {
 267     }
 268
 269     void safePoint(uint64_t ammount) throw(theory::Interrupted, UnsafeInterruptException, AssertionException) {
 270       spendResource(ammount);
 271       if (d_engine->d_interrupted) {
 272         throw theory::Interrupted();
 273       }
 274     }
 275
 276     void conflict(TNode conflictNode, Proof* pf = NULL) throw(AssertionException, UnsafeInterruptException);
 277
 278     bool propagate(TNode literal) throw(AssertionException, UnsafeInterruptException);
 279
 280     theory::LemmaStatus lemma(TNode lemma,
 281                               ProofRule rule,
 282                               bool removable = false,
 283                               bool preprocess = false,
 284                               bool sendAtoms = false);
 285
 286     theory::LemmaStatus splitLemma(TNode lemma, bool removable = false);
 287
 288     void demandRestart() throw(TypeCheckingExceptionPrivate, AssertionException, UnsafeInterruptException) {
 289       NodeManager* curr = NodeManager::currentNM();
 290       Node restartVar =  curr->mkSkolem("restartVar",
 291                                         curr->booleanType(),
 292                                         "A boolean variable asserted to be true to force a restart");
 293       Trace("theory::restart") << "EngineOutputChannel<" << d_theory << ">::restart(" << restartVar << ")" << std::endl;
 294       ++ d_statistics.restartDemands;
 295       lemma(restartVar, RULE_INVALID, true);
 296     }
 297
 298     void requirePhase(TNode n, bool phase)
 299       throw(theory::Interrupted, AssertionException, UnsafeInterruptException) {
 300       Debug("theory") << "EngineOutputChannel::requirePhase("
 301                       << n << ", " << phase << ")" << std::endl;
 302       ++ d_statistics.requirePhase;
 303       d_engine->d_propEngine->requirePhase(n, phase);
 304     }
 305
 306     bool flipDecision()
 307       throw(theory::Interrupted, AssertionException, UnsafeInterruptException) {
 308       Debug("theory") << "EngineOutputChannel::flipDecision()" << std::endl;
 309       ++ d_statistics.flipDecision;
 310       return d_engine->d_propEngine->flipDecision();
 311     }
 312
 313     void setIncomplete() throw(AssertionException, UnsafeInterruptException) {
 314       Trace("theory") << "TheoryEngine::setIncomplete()" << std::endl;
 315       d_engine->setIncomplete(d_theory);
 316     }
 317
 318     void spendResource(unsigned ammount) throw(UnsafeInterruptException) {
 319       d_engine->spendResource(ammount);
 320     }
 321
 322     void handleUserAttribute( const char* attr, theory::Theory* t ){
 323       d_engine->handleUserAttribute( attr, t );
 324     }
 325
 326   private:
 327
 328     /**
 329      * A helper function for registering lemma recipes with the proof engine
 330      */
 331     void registerLemmaRecipe(Node lemma, Node originalLemma, bool preprocess, theory::TheoryId theoryId);
 332   };/* class TheoryEngine::EngineOutputChannel */
 333
 334   /**
 335    * Output channels for individual theories.
 336    */
 337   EngineOutputChannel* d_theoryOut[theory::THEORY_LAST];
 338
 339   /**
 340    * Are we in conflict.
 341    */
 342   context::CDO<bool> d_inConflict;
 343
 344   /**
 345    * Called by the theories to notify of a conflict.
 346    */
 347   void conflict(TNode conflict, theory::TheoryId theoryId);
 348
 349   /**
 350    * Debugging flag to ensure that shutdown() is called before the
 351    * destructor.
 352    */
 353   bool d_hasShutDown;
 354
 355   /**
 356    * True if a theory has notified us of incompleteness (at this
 357    * context level or below).
 358    */
 359   context::CDO<bool> d_incomplete;
 360
 361   /**
 362    * Called by the theories to notify that the current branch is incomplete.
 363    */
 364   void setIncomplete(theory::TheoryId theory) {
 365     d_incomplete = true;
 366   }
 367
 368
 369   /**
 370    * Mapping of propagations from recievers to senders.
 371    */
 372   typedef context::CDHashMap<NodeTheoryPair, NodeTheoryPair, NodeTheoryPairHashFunction> PropagationMap;
 373   PropagationMap d_propagationMap;
 374
 375   /**
 376    * Timestamp of propagations
 377    */
 378   context::CDO<size_t> d_propagationMapTimestamp;
 379
 380   /**
 381    * Literals that are propagated by the theory. Note that these are TNodes.
 382    * The theory can only propagate nodes that have an assigned literal in the
 383    * SAT solver and are hence referenced in the SAT solver.
 384    */
 385   context::CDList<TNode> d_propagatedLiterals;
 386
 387   /**
 388    * The index of the next literal to be propagated by a theory.
 389    */
 390   context::CDO<unsigned> d_propagatedLiteralsIndex;
 391
 392   /**
 393    * Called by the output channel to propagate literals and facts
 394    * @return false if immediate conflict
 395    */
 396   bool propagate(TNode literal, theory::TheoryId theory);
 397
 398   /**
 399    * Internal method to call the propagation routines and collect the
 400    * propagated literals.
 401    */
 402   void propagate(theory::Theory::Effort effort);
 403
 404   /**
 405    * Called by the output channel to request decisions "as soon as
 406    * possible."
 407    */
 408   void propagateAsDecision(TNode literal, theory::TheoryId theory);
 409
 410   /**
 411    * A variable to mark if we added any lemmas.
 412    */
 413   bool d_lemmasAdded;
 414
 415   /**
 416    * A variable to mark if the OutputChannel was "used" by any theory
 417    * since the start of the last check.  If it has been, we require
 418    * a FULL_EFFORT check before exiting and reporting SAT.
 419    *
 420    * See the documentation for the needCheck() function, below.
 421    */
 422   bool d_outputChannelUsed;
 423
 424   /** Atom requests from lemmas */
 425   AtomRequests d_atomRequests;
 426
 427   /**
 428    * Adds a new lemma, returning its status.
 429    * @param node the lemma
 430    * @param negated should the lemma be asserted negated
 431    * @param removable can the lemma be remove (restrictions apply)
 432    * @param needAtoms if not THEORY_LAST, then
 433    */
 434   theory::LemmaStatus lemma(TNode node,
 435                             ProofRule rule,
 436                             bool negated,
 437                             bool removable,
 438                             bool preprocess,
 439                             theory::TheoryId atomsTo);
 440
 441   /** Enusre that the given atoms are send to the given theory */
 442   void ensureLemmaAtoms(const std::vector<TNode>& atoms, theory::TheoryId theory);
 443
 444   RemoveTermFormulas& d_tform_remover;
 445
 446   /** sort inference module */
 447   SortInference d_sortInfer;
 448
 449   /** Time spent in theory combination */
 450   TimerStat d_combineTheoriesTime;
 451
 452   Node d_true;
 453   Node d_false;
 454
 455   /** Whether we were just interrupted (or not) */
 456   bool d_interrupted;
 457   ResourceManager* d_resourceManager;
 458
 459   /** Container for lemma input and output channels. */
 460   LemmaChannels* d_channels;
 461
 462 public:
 463
 464   /** Constructs a theory engine */
 465   TheoryEngine(context::Context* context, context::UserContext* userContext,
 466                RemoveTermFormulas& iteRemover, const LogicInfo& logic,
 467                LemmaChannels* channels);
 468
 469   /** Destroys a theory engine */
 470   ~TheoryEngine();
 471
 472   void interrupt() throw(ModalException);
 473   /**
 474    * "Spend" a resource during a search or preprocessing.
 475    */
 476   void spendResource(unsigned ammount);
 477
 478   /**
 479    * Adds a theory. Only one theory per TheoryId can be present, so if
 480    * there is another theory it will be deleted.
 481    */
 482   template <class TheoryClass>
 483   inline void addTheory(theory::TheoryId theoryId) {
 484     Assert(d_theoryTable[theoryId] == NULL && d_theoryOut[theoryId] == NULL);
 485     d_theoryOut[theoryId] = new EngineOutputChannel(this, theoryId);
 486     d_theoryTable[theoryId] =
 487         new TheoryClass(d_context, d_userContext, *d_theoryOut[theoryId],
 488                         theory::Valuation(this), d_logicInfo);
 489   }
 490
 491   inline void setPropEngine(prop::PropEngine* propEngine) {
 492     Assert(d_propEngine == NULL);
 493     d_propEngine = propEngine;
 494   }
 495
 496   inline void setDecisionEngine(DecisionEngine* decisionEngine) {
 497     Assert(d_decisionEngine == NULL);
 498     d_decisionEngine = decisionEngine;
 499   }
 500
 501   /** Called when all initialization of options/logic is done */
 502   void finishInit();
 503
 504   /**
 505    * Get a pointer to the underlying propositional engine.
 506    */
 507   inline prop::PropEngine* getPropEngine() const {
 508     return d_propEngine;
 509   }
 510
 511   /**
 512    * Get a pointer to the underlying sat context.
 513    */
 514   inline context::Context* getSatContext() const {
 515     return d_context;
 516   }
 517
 518   /**
 519    * Get a pointer to the underlying user context.
 520    */
 521   inline context::Context* getUserContext() const {
 522     return d_userContext;
 523   }
 524
 525   /**
 526    * Get a pointer to the underlying quantifiers engine.
 527    */
 528   theory::QuantifiersEngine* getQuantifiersEngine() const {
 529     return d_quantEngine;
 530   }
 531
 532 private:
 533
 534   /**
 535    * Helper for preprocess
 536    */
 537   Node ppTheoryRewrite(TNode term);
 538
 539   /**
 540    * Queue of nodes for pre-registration.
 541    */
 542   std::queue<TNode> d_preregisterQueue;
 543
 544   /**
 545    * Boolean flag denoting we are in pre-registration.
 546    */
 547   bool d_inPreregister;
 548
 549   /**
 550    * Did the theories get any new facts since the last time we called
 551    * check()
 552    */
 553   context::CDO<bool> d_factsAsserted;
 554
 555   /**
 556    * Map from equality atoms to theories that would like to be notified about them.
 557    */
 558
 559
 560   /**
 561    * Assert the formula to the given theory.
 562    * @param assertion the assertion to send (not necesserily normalized)
 563    * @param original the assertion as it was sent in from the propagating theory
 564    * @param toTheoryId the theory to assert to
 565    * @param fromTheoryId the theory that sent it
 566    */
 567   void assertToTheory(TNode assertion, TNode originalAssertion, theory::TheoryId toTheoryId, theory::TheoryId fromTheoryId);
 568
 569   /**
 570    * Marks a theory propagation from a theory to a theory where a
 571    * theory could be the THEORY_SAT_SOLVER for literals coming from
 572    * or being propagated to the SAT solver. If the receiving theory
 573    * already recieved the literal, the method returns false, otherwise
 574    * it returns true.
 575    *
 576    * @param assertion the normalized assertion being sent
 577    * @param originalAssertion the actual assertion that was sent
 578    * @param toTheoryId the theory that is on the receiving end
 579    * @param fromTheoryId the theory that sent the assertino
 580    * @return true if a new assertion, false if theory already got it
 581    */
 582   bool markPropagation(TNode assertion, TNode originalAssertions, theory::TheoryId toTheoryId, theory::TheoryId fromTheoryId);
 583
 584   /**
 585    * Computes the explanation by travarsing the propagation graph and
 586    * asking relevant theories to explain the propagations. Initially
 587    * the explanation vector should contain only the element (node, theory)
 588    * where the node is the one to be explained, and the theory is the
 589    * theory that sent the literal. The lemmaProofRecipe will contain a list
 590    * of the explanation steps required to produce the original node.
 591    */
 592   void getExplanation(std::vector<NodeTheoryPair>& explanationVector, LemmaProofRecipe* lemmaProofRecipe);
 593
 594 public:
 595
 596   /**
 597    * Signal the start of a new round of assertion preprocessing
 598    */
 599   void preprocessStart();
 600
 601   /**
 602    * Runs theory specific preprocessing on the non-Boolean parts of
 603    * the formula.  This is only called on input assertions, after ITEs
 604    * have been removed.
 605    */
 606   Node preprocess(TNode node);
 607
 608   /** Notify (preprocessed) assertions. */
 609   void notifyPreprocessedAssertions(const std::vector<Node>& assertions);
 610
 611   /** Return whether or not we are incomplete (in the current context). */
 612   inline bool isIncomplete() const { return d_incomplete; }
 613
 614   /**
 615    * Returns true if we need another round of checking.  If this
 616    * returns true, check(FULL_EFFORT) _must_ be called by the
 617    * propositional layer before reporting SAT.
 618    *
 619    * This is especially necessary for incomplete theories that lazily
 620    * output some lemmas on FULL_EFFORT check (e.g. quantifier reasoning
 621    * outputing quantifier instantiations).  In such a case, a lemma can
 622    * be asserted that is simplified away (perhaps it's already true).
 623    * However, we must maintain the invariant that, if a theory uses the
 624    * OutputChannel, it implicitly requests that another check(FULL_EFFORT)
 625    * be performed before exit, even if no new facts are on its fact queue,
 626    * as it might decide to further instantiate some lemmas, precluding
 627    * a SAT response.
 628    */
 629   inline bool needCheck() const {
 630     return d_outputChannelUsed || d_lemmasAdded;
 631   }
 632
 633   /**
 634    * This is called at shutdown time by the SmtEngine, just before
 635    * destruction.  It is important because there are destruction
 636    * ordering issues between PropEngine and Theory.
 637    */
 638   void shutdown();
 639
 640   /**
 641    * Solve the given literal with a theory that owns it.
 642    */
 643   theory::Theory::PPAssertStatus solve(TNode literal,
 644                                     theory::SubstitutionMap& substitutionOut);
 645
 646   /**
 647    * Preregister a Theory atom with the responsible theory (or
 648    * theories).
 649    */
 650   void preRegister(TNode preprocessed);
 651
 652   /**
 653    * Assert the formula to the appropriate theory.
 654    * @param node the assertion
 655    */
 656   void assertFact(TNode node);
 657
 658   /**
 659    * Check all (currently-active) theories for conflicts.
 660    * @param effort the effort level to use
 661    */
 662   void check(theory::Theory::Effort effort);
 663
 664   /**
 665    * Run the combination framework.
 666    */
 667   void combineTheories();
 668
 669   /**
 670    * Calls ppStaticLearn() on all theories, accumulating their
 671    * combined contributions in the "learned" builder.
 672    */
 673   void ppStaticLearn(TNode in, NodeBuilder<>& learned);
 674
 675   /**
 676    * Calls presolve() on all theories and returns true
 677    * if one of the theories discovers a conflict.
 678    */
 679   bool presolve();
 680
 681    /**
 682    * Calls postsolve() on all theories.
 683    */
 684   void postsolve();
 685
 686   /**
 687    * Calls notifyRestart() on all active theories.
 688    */
 689   void notifyRestart();
 690
 691   void getPropagatedLiterals(std::vector<TNode>& literals) {
 692     for (; d_propagatedLiteralsIndex < d_propagatedLiterals.size(); d_propagatedLiteralsIndex = d_propagatedLiteralsIndex + 1) {
 693       Debug("getPropagatedLiterals") << "TheoryEngine::getPropagatedLiterals: propagating: " << d_propagatedLiterals[d_propagatedLiteralsIndex] << std::endl;
 694       literals.push_back(d_propagatedLiterals[d_propagatedLiteralsIndex]);
 695     }
 696   }
 697
 698   Node getNextDecisionRequest();
 699
 700   bool properConflict(TNode conflict) const;
 701   bool properPropagation(TNode lit) const;
 702   bool properExplanation(TNode node, TNode expl) const;
 703
 704   /**
 705    * Returns an explanation of the node propagated to the SAT solver.
 706    */
 707   Node getExplanation(TNode node);
 708
 709   /**
 710    * Returns an explanation of the node propagated to the SAT solver and the theory
 711    * that propagated it.
 712    */
 713   Node getExplanationAndRecipe(TNode node, LemmaProofRecipe* proofRecipe);
 714
 715   /**
 716    * collect model info
 717    */
 718   void collectModelInfo( theory::TheoryModel* m );
 719   /** post process model */
 720   void postProcessModel( theory::TheoryModel* m );
 721
 722   /**
 723    * Get the current model
 724    */
 725   theory::TheoryModel* getModel();
 726
 727   /**
 728    * Get the model builder
 729    */
 730   theory::TheoryEngineModelBuilder* getModelBuilder() { return d_curr_model_builder; }
 731
 732   /**
 733    * Get the theory associated to a given Node.
 734    *
 735    * @returns the theory, or NULL if the TNode is
 736    * of built-in type.
 737    */
 738   inline theory::Theory* theoryOf(TNode node) const {
 739     return d_theoryTable[theory::Theory::theoryOf(node)];
 740   }
 741
 742   /**
 743    * Get the theory associated to a the given theory id.
 744    *
 745    * @returns the theory
 746    */
 747   inline theory::Theory* theoryOf(theory::TheoryId theoryId) const {
 748     return d_theoryTable[theoryId];
 749   }
 750
 751   inline bool isTheoryEnabled(theory::TheoryId theoryId) const {
 752     return d_logicInfo.isTheoryEnabled(theoryId);
 753   }
 754
 755   /**
 756    * Returns the equality status of the two terms, from the theory
 757    * that owns the domain type.  The types of a and b must be the same.
 758    */
 759   theory::EqualityStatus getEqualityStatus(TNode a, TNode b);
 760
 761   /**
 762    * Returns the value that a theory that owns the type of var currently
 763    * has (or null if none);
 764    */
 765   Node getModelValue(TNode var);
 766
 767   /**
 768    * Takes a literal and returns an equivalent literal that is guaranteed to be a SAT literal
 769    */
 770   Node ensureLiteral(TNode n);
 771
 772   /**
 773    * Print all instantiations made by the quantifiers module.
 774    */
 775   void printInstantiations( std::ostream& out );
 776
 777   /**
 778    * Print solution for synthesis conjectures found by ce_guided_instantiation module
 779    */
 780   void printSynthSolution( std::ostream& out );
 781
 782   /**
 783    * Get list of quantified formulas that were instantiated
 784    */
 785   void getInstantiatedQuantifiedFormulas( std::vector< Node >& qs );
 786
 787   /**
 788    * Get instantiation methods
 789    *   first inputs forall x.q[x] and returns ( q[a], ..., q[z] )
 790    *   second inputs forall x.q[x] and returns ( a, ..., z )
 791    *   third and fourth return mappings e.g. forall x.q1[x] -> ( q1[a]...q1[z] ) , ... , forall x.qn[x] -> ( qn[a]...qn[z] )
 792    */
 793   void getInstantiations( Node q, std::vector< Node >& insts );
 794   void getInstantiationTermVectors( Node q, std::vector< std::vector< Node > >& tvecs );
 795   void getInstantiations( std::map< Node, std::vector< Node > >& insts );
 796   void getInstantiationTermVectors( std::map< Node, std::vector< std::vector< Node > > >& insts );
 797
 798   /**
 799    * Get instantiated conjunction, returns q[t1] ^ ... ^ q[tn] where t1...tn are current set of instantiations for q.
 800    *   Can be used for quantifier elimination when satisfiable and q[t1] ^ ... ^ q[tn] |= q
 801    */
 802   Node getInstantiatedConjunction( Node q );
 803
 804   /**
 805    * Forwards an entailment check according to the given theoryOfMode.
 806    * See theory.h for documentation on entailmentCheck().
 807    */
 808   std::pair<bool, Node> entailmentCheck(theory::TheoryOfMode mode, TNode lit, const theory::EntailmentCheckParameters* params = NULL, theory::EntailmentCheckSideEffects* out = NULL);
 809
 810 private:
 811
 812   /** Default visitor for pre-registration */
 813   PreRegisterVisitor d_preRegistrationVisitor;
 814
 815   /** Visitor for collecting shared terms */
 816   SharedTermsVisitor d_sharedTermsVisitor;
 817
 818   /** Dump the assertions to the dump */
 819   void dumpAssertions(const char* tag);
 820
 821   /**
 822    * A collection of ite preprocessing passes.
 823    */
 824   theory::ITEUtilities* d_iteUtilities;
 825
 826
 827   /** For preprocessing pass simplifying unconstrained expressions */
 828   UnconstrainedSimplifier* d_unconstrainedSimp;
 829
 830   /** For preprocessing pass lifting bit-vectors of size 1 to booleans */
 831   theory::bv::BvToBoolPreprocessor d_bvToBoolPreprocessor;
 832 public:
 833   void staticInitializeBVOptions(const std::vector<Node>& assertions);
 834   void ppBvToBool(const std::vector<Node>& assertions, std::vector<Node>& new_assertions);
 835   void ppBoolToBv(const std::vector<Node>& assertions, std::vector<Node>& new_assertions);
 836   bool ppBvAbstraction(const std::vector<Node>& assertions, std::vector<Node>& new_assertions);
 837   void mkAckermanizationAssertions(std::vector<Node>& assertions);
 838
 839   Node ppSimpITE(TNode assertion);
 840   /** Returns false if an assertion simplified to false. */
 841   bool donePPSimpITE(std::vector<Node>& assertions);
 842
 843   void ppUnconstrainedSimp(std::vector<Node>& assertions);
 844
 845   SharedTermsDatabase* getSharedTermsDatabase() { return &d_sharedTerms; }
 846
 847   theory::eq::EqualityEngine* getMasterEqualityEngine() { return d_masterEqualityEngine; }
 848
 849   RemoveTermFormulas* getTermFormulaRemover() { return &d_tform_remover; }
 850
 851   SortInference* getSortInference() { return &d_sortInfer; }
 852
 853   /** Prints the assertions to the debug stream */
 854   void printAssertions(const char* tag);
 855
 856   /** Theory alternative is in use. */
 857   bool useTheoryAlternative(const std::string& name);
 858
 859   /** Enables using a theory alternative by name. */
 860   void enableTheoryAlternative(const std::string& name);
 861
 862 private:
 863   std::set< std::string > d_theoryAlternatives;
 864
 865   std::map< std::string, std::vector< theory::Theory* > > d_attr_handle;
 866 public:
 867
 868   /**
 869    * Set user attribute.
 870    * This function is called when an attribute is set by a user.  In SMT-LIBv2 this is done
 871    * via the syntax (! n :attr)
 872    */
 873   void setUserAttribute(const std::string& attr, Node n, std::vector<Node>& node_values, std::string str_value);
 874
 875   /**
 876    * Handle user attribute.
 877    * Associates theory t with the attribute attr.  Theory t will be
 878    * notified whenever an attribute of name attr is set.
 879    */
 880   void handleUserAttribute(const char* attr, theory::Theory* t);
 881
 882   /**
 883    * Check that the theory assertions are satisfied in the model.
 884    * This function is called from the smt engine's checkModel routine.
 885    */
 886   void checkTheoryAssertionsWithModel();
 887
 888 private:
 889   IntStat d_arithSubstitutionsAdded;
 890
 891 };/* class TheoryEngine */
 892
 893 }/* CVC4 namespace */
 894
 895 #endif /* __CVC4__THEORY_ENGINE_H */