1 /********************* */
2 /*! \file synth_conjecture.h
4 ** Top contributors (to current version):
5 ** Andrew Reynolds, Mathias Preiner, Haniel Barbosa
6 ** This file is part of the CVC4 project.
7 ** Copyright (c) 2009-2020 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
12 ** \brief Class that encapsulates techniques for a single (SyGuS) synthesis
16 #include "cvc4_private.h"
18 #ifndef CVC4__THEORY__QUANTIFIERS__SYNTH_CONJECTURE_H
19 #define CVC4__THEORY__QUANTIFIERS__SYNTH_CONJECTURE_H
23 #include "theory/decision_manager.h"
24 #include "theory/quantifiers/expr_miner_manager.h"
25 #include "theory/quantifiers/sygus/ce_guided_single_inv.h"
26 #include "theory/quantifiers/sygus/cegis.h"
27 #include "theory/quantifiers/sygus/cegis_core_connective.h"
28 #include "theory/quantifiers/sygus/cegis_unif.h"
29 #include "theory/quantifiers/sygus/example_eval_cache.h"
30 #include "theory/quantifiers/sygus/example_infer.h"
31 #include "theory/quantifiers/sygus/sygus_grammar_cons.h"
32 #include "theory/quantifiers/sygus/sygus_pbe.h"
33 #include "theory/quantifiers/sygus/sygus_process_conj.h"
34 #include "theory/quantifiers/sygus/sygus_repair_const.h"
35 #include "theory/quantifiers/sygus/sygus_stats.h"
39 namespace quantifiers
{
42 class SygusStatistics
;
45 * A base class for generating values for actively-generated enumerators.
46 * At a high level, the job of this class is to accept a stream of "abstract
47 * values" a1, ..., an, ..., and generate a (possibly larger) stream of
48 * "concrete values" c11, ..., c1{m_1}, ..., cn1, ... cn{m_n}, ....
50 class EnumValGenerator
53 virtual ~EnumValGenerator() {}
54 /** initialize this class with enumerator e */
55 virtual void initialize(Node e
) = 0;
56 /** Inform this generator that abstract value v was enumerated. */
57 virtual void addValue(Node v
) = 0;
59 * Increment this value generator. If this returns false, then we are out of
60 * values. If this returns true, getCurrent(), if non-null, returns the
63 * Notice that increment() may return true and afterwards it may be the case
64 * getCurrent() is null. We do this so that increment() does not take too
65 * much time per call, which can be the case for grammars where it is
66 * difficult to find the next (non-redundant) term. Returning true with
67 * a null current term gives the caller the chance to interleave other
70 virtual bool increment() = 0;
71 /** Get the current concrete value generated by this class. */
72 virtual Node
getCurrent() = 0;
75 /** a synthesis conjecture
76 * This class implements approaches for a synthesis conjecture, given by data
78 * This includes both approaches for synthesis in Reynolds et al CAV 2015. It
79 * determines which approach and optimizations are applicable to the
80 * conjecture, and has interfaces for implementing them.
85 SynthConjecture(QuantifiersEngine
* qe
, SynthEngine
* p
, SygusStatistics
& s
);
89 /** get original version of conjecture */
90 Node
getConjecture() const { return d_quant
; }
91 /** get deep embedding version of conjecture */
92 Node
getEmbeddedConjecture() const { return d_embed_quant
; }
93 //-------------------------------for counterexample-guided check/refine
94 /** whether the conjecture is waiting for a call to doCheck below */
96 /** whether the conjecture is waiting for a call to doRefine below */
97 bool needsRefinement() const;
98 /** do syntax-guided enumerative check
100 * This is step 2(a) of Figure 3 of Reynolds et al CAV 2015.
102 * The method returns true if this conjecture is finished trying solutions
103 * for the given call to SynthEngine::check.
105 * Notice that we make multiple calls to doCheck on one call to
106 * SynthEngine::check. For example, if we are using an actively-generated
107 * enumerator, one enumerated (abstract) term may correspond to multiple
108 * concrete terms t1, ..., tn to check, where we make up to n calls to doCheck
109 * when each of t1, ..., tn fails to satisfy the current refinement lemmas.
111 bool doCheck(std::vector
<Node
>& lems
);
114 * This is step 2(b) of Figure 3 of Reynolds et al CAV 2015.
116 * This method is run when needsRefinement() returns true, indicating that
117 * the last call to doCheck found a counterexample to the last candidate.
119 * This method adds a refinement lemma on the output channel of quantifiers
120 * engine. If the refinement lemma is a duplicate, then we manually
121 * exclude the current candidate via excludeCurrentSolution. This should
122 * only occur when the synthesis conjecture for the current candidate fails
123 * to evaluate to false for a given counterexample point, but regardless its
124 * negation is satisfiable for the current candidate and that point. This is
125 * exclusive to theories with partial functions, e.g. (non-linear) division.
127 * This method returns true if a lemma was added on the output channel, and
131 //-------------------------------end for counterexample-guided check/refine
133 * Prints the synthesis solution to output stream out. This invokes solution
134 * reconstruction if the conjecture is single invocation. Otherwise, it
135 * returns the solution found by sygus enumeration.
137 void printSynthSolution(std::ostream
& out
);
138 /** get synth solutions
140 * This method returns true if this class has a solution available to the
141 * conjecture that it was assigned.
143 * Let q be the synthesis conjecture assigned to this class.
144 * This method adds entries to sol_map[q] that map functions-to-synthesize to
145 * their builtin solution, which has the same type. For example, for synthesis
146 * conjecture exists f. forall x. f( x )>x, this function will update
147 * sol_map[q] to contain the entry:
148 * f -> (lambda x. x+1)
150 bool getSynthSolutions(std::map
<Node
, std::map
<Node
, Node
> >& sol_map
);
152 * The feasible guard whose semantics are "this conjecture is feasiable".
153 * This is "G" in Figure 3 of Reynolds et al CAV 2015.
155 Node
getGuard() const;
157 bool isGround() { return d_inner_vars
.empty(); }
158 /** are we using single invocation techniques */
159 bool isSingleInvocation() const;
160 /** preregister conjecture
161 * This is used as a heuristic for solution reconstruction, so that we
162 * remember expressions in the conjecture before preprocessing, since they
163 * may be helpful during solution reconstruction (Figure 5 of Reynolds et al
166 void preregisterConjecture(Node q
);
167 /** assign conjecture q to this class */
169 /** has a conjecture been assigned to this class */
170 bool isAssigned() { return !d_embed_quant
.isNull(); }
172 * Get model value for term n.
174 Node
getModelValue(Node n
);
176 /** get utility for static preprocessing and analysis of conjectures */
177 SynthConjectureProcess
* getProcess() { return d_ceg_proc
.get(); }
178 /** get constant repair utility */
179 SygusRepairConst
* getRepairConst() { return d_sygus_rconst
.get(); }
180 /** get example inference utility */
181 ExampleInfer
* getExampleInfer() { return d_exampleInfer
.get(); }
182 /** get the example evaluation cache utility for enumerator e */
183 ExampleEvalCache
* getExampleEvalCache(Node e
);
184 /** get program by examples module */
185 SygusPbe
* getPbe() { return d_ceg_pbe
.get(); }
186 /** get the symmetry breaking predicate for type */
187 Node
getSymmetryBreakingPredicate(
188 Node x
, Node e
, TypeNode tn
, unsigned tindex
, unsigned depth
);
189 /** print out debug information about this conjecture */
190 void debugPrint(const char* c
);
191 /** check side condition
193 * This returns false if the solution { d_candidates -> cvals } does not
194 * satisfy the side condition of the conjecture maintained by this class,
195 * if it exists, and true otherwise.
197 bool checkSideCondition(const std::vector
<Node
>& cvals
) const;
200 /** reference to quantifier engine */
201 QuantifiersEngine
* d_qe
;
202 /** pointer to the synth engine that owns this */
203 SynthEngine
* d_parent
;
204 /** reference to the statistics of parent */
205 SygusStatistics
& d_stats
;
206 /** term database sygus of d_qe */
208 /** The feasible guard. */
209 Node d_feasible_guard
;
211 * Do we have a solution in this solve context? This flag is reset to false
212 * on every call to presolve.
215 /** the decision strategy for the feasible guard */
216 std::unique_ptr
<DecisionStrategy
> d_feasible_strategy
;
217 /** single invocation utility */
218 std::unique_ptr
<CegSingleInv
> d_ceg_si
;
219 /** utility for static preprocessing and analysis of conjectures */
220 std::unique_ptr
<SynthConjectureProcess
> d_ceg_proc
;
221 /** grammar utility */
222 std::unique_ptr
<CegGrammarConstructor
> d_ceg_gc
;
223 /** repair constant utility */
224 std::unique_ptr
<SygusRepairConst
> d_sygus_rconst
;
225 /** example inference utility */
226 std::unique_ptr
<ExampleInfer
> d_exampleInfer
;
227 /** example evaluation cache utility for each enumerator */
228 std::map
<Node
, std::unique_ptr
<ExampleEvalCache
> > d_exampleEvalCache
;
230 //------------------------modules
231 /** program by examples module */
232 std::unique_ptr
<SygusPbe
> d_ceg_pbe
;
234 std::unique_ptr
<Cegis
> d_ceg_cegis
;
235 /** CEGIS UNIF module */
236 std::unique_ptr
<CegisUnif
> d_ceg_cegisUnif
;
237 /** connective core utility */
238 std::unique_ptr
<CegisCoreConnective
> d_sygus_ccore
;
239 /** the set of active modules (subset of the above list) */
240 std::vector
<SygusModule
*> d_modules
;
243 * This is the module (one of those above) that takes sole responsibility
244 * for this conjecture, determined during assign(...).
246 SygusModule
* d_master
;
247 //------------------------end modules
249 //------------------------enumerators
251 * Get model values for terms n, store in vector v. This method returns true
252 * if and only if all values added to v are non-null.
254 * The argument activeIncomplete indicates whether n contains an active
255 * enumerator that is currently not finished enumerating values, but returned
256 * null on a call to getEnumeratedValue. This value is used for determining
257 * whether we should call getEnumeratedValues again within a call to
258 * SynthConjecture::check.
260 * It removes terms from n that correspond to "inactive" enumerators, that
261 * is, enumerators whose values have been exhausted.
263 bool getEnumeratedValues(std::vector
<Node
>& n
,
264 std::vector
<Node
>& v
,
265 bool& activeIncomplete
);
267 * Get model value for term n. If n has a value that was excluded by
268 * datatypes sygus symmetry breaking, this method returns null. It sets
269 * activeIncomplete to true if there is an actively-generated enumerator whose
270 * current value is null but it has not finished generating values.
272 Node
getEnumeratedValue(Node n
, bool& activeIncomplete
);
273 /** enumerator generators for each actively-generated enumerator */
274 std::map
<Node
, std::unique_ptr
<EnumValGenerator
> > d_evg
;
276 * Map from enumerators to whether they are currently being
277 * "actively-generated". That is, we are in a state where we have called
278 * d_evg[e].addValue(v) for some v, and d_evg[e].getNext() has not yet
279 * returned null. The range of this map stores the abstract value that
280 * we are currently generating values from.
282 std::map
<Node
, Node
> d_ev_curr_active_gen
;
283 /** the current waiting value of each actively-generated enumerator, if any
285 * This caches values that are actively generated and that we have not yet
286 * passed to a call to SygusModule::constructCandidates. An example of when
287 * this may occur is when there are two actively-generated enumerators e1 and
288 * e2. Say on some iteration we actively-generate v1 for e1, the value
289 * of e2 was excluded by symmetry breaking, and say the current master sygus
290 * module does not handle partial models. Hence, we abort the current check.
291 * We remember that the value of e1 was v1 by storing it here, so that on
292 * a future check when v2 has a proper value, it is returned.
294 std::map
<Node
, Node
> d_ev_active_gen_waiting
;
295 /** the first value enumerated for each actively-generated enumerator
297 * This is to implement an optimization that only guards the blocking lemma
298 * for the first value of an actively-generated enumerator.
300 std::map
<Node
, Node
> d_ev_active_gen_first_val
;
301 //------------------------end enumerators
303 /** list of constants for quantified formula
304 * The outer Skolems for the negation of d_embed_quant.
306 std::vector
<Node
> d_candidates
;
307 /** base instantiation
308 * If d_embed_quant is forall d. exists y. P( d, y ), then
309 * this is the formula exists y. P( d_candidates, y ). Notice that
310 * (exists y. F) is shorthand above for ~( forall y. ~F ).
313 /** list of variables on inner quantification */
314 std::vector
<Node
> d_inner_vars
;
316 * The set of skolems for the current "verification" lemma, if one exists.
317 * This may be added to during calls to doCheck(). The model values for these
318 * skolems are analyzed during doRefine().
320 std::vector
<Node
> d_ce_sk_vars
;
322 * If we have already tested the satisfiability of the current verification
323 * lemma, this stores the model values of d_ce_sk_vars in the current
324 * (satisfiable, failed) verification lemma.
326 std::vector
<Node
> d_ce_sk_var_mvs
;
328 * Whether the above vector has been set. We have this flag since the above
329 * vector may be set to empty (e.g. for ground synthesis conjectures).
331 bool d_set_ce_sk_vars
;
333 /** the asserted (negated) conjecture */
336 * The side condition for solving the conjecture, after conversion to deep
339 Node d_embedSideCondition
;
340 /** (negated) conjecture after simplification */
342 /** (negated) conjecture after simplification, conversion to deep embedding */
344 /** candidate information */
349 /** list of terms we have instantiated candidates with */
350 std::vector
<Node
> d_inst
;
352 std::map
<Node
, CandidateInfo
> d_cinfo
;
354 * The first index of an instantiation in CandidateInfo::d_inst that we have
355 * not yet tried to repair.
357 unsigned d_repair_index
;
358 /** number of times we have called doRefine */
359 unsigned d_refine_count
;
360 /** get candidadate */
361 Node
getCandidate(unsigned int i
) { return d_candidates
[i
]; }
362 /** record instantiation (this is used to construct solutions later) */
363 void recordInstantiation(std::vector
<Node
>& vs
)
365 Assert(vs
.size() == d_candidates
.size());
366 for (unsigned i
= 0; i
< vs
.size(); i
++)
368 d_cinfo
[d_candidates
[i
]].d_inst
.push_back(vs
[i
]);
371 /** get synth solutions internal
373 * This function constructs the body of solutions for all
374 * functions-to-synthesize in this conjecture and stores them in sols, in
375 * order. For each solution added to sols, we add an integer indicating what
376 * kind of solution n is, where if sols[i] = n, then
377 * if status[i] = 0: n is the (builtin term) corresponding to the solution,
378 * if status[i] = 1: n is the sygus representation of the solution.
379 * We store builtin versions under some conditions (such as when the sygus
380 * grammar is being ignored).
382 * This consults the single invocation module to get synthesis solutions if
383 * isSingleInvocation() returns true.
385 * For example, for conjecture exists fg. forall x. f(x)>g(x), this function
386 * may set ( sols, status ) to ( { x+1, d_x() }, { 1, 0 } ), where d_x() is
387 * the sygus datatype constructor corresponding to variable x.
389 bool getSynthSolutionsInternal(std::vector
<Node
>& sols
,
390 std::vector
<int>& status
);
391 //-------------------------------- sygus stream
392 /** current stream guard */
393 Node d_current_stream_guard
;
394 /** the decision strategy for streaming solutions */
395 class SygusStreamDecisionStrategy
: public DecisionStrategyFmf
398 SygusStreamDecisionStrategy(context::Context
* satContext
,
399 Valuation valuation
);
401 Node
mkLiteral(unsigned i
) override
;
403 std::string
identify() const override
405 return std::string("sygus_stream");
408 std::unique_ptr
<SygusStreamDecisionStrategy
> d_stream_strategy
;
409 /** get current stream guard */
410 Node
getCurrentStreamGuard() const;
411 /** get stream guarded lemma
413 * If sygusStream is enabled, this returns ( G V n ) where G is the guard
414 * returned by getCurrentStreamGuard, otherwise this returns n.
416 Node
getStreamGuardedLemma(Node n
) const;
418 * Prints the current synthesis solution to the output stream indicated by
419 * the Options object, send a lemma blocking the current solution to the
420 * output channel, which we refer to as a "stream exclusion lemma".
422 * The argument enums is the set of enumerators that comprise the current
423 * solution, and values is their current values.
425 void printAndContinueStream(const std::vector
<Node
>& enums
,
426 const std::vector
<Node
>& values
);
427 /** exclude the current solution { enums -> values } */
428 void excludeCurrentSolution(const std::vector
<Node
>& enums
,
429 const std::vector
<Node
>& values
);
431 * Whether we have guarded a stream exclusion lemma when using sygusStream.
432 * This is an optimization that allows us to guard only the first stream
435 bool d_guarded_stream_exc
;
436 //-------------------------------- end sygus stream
437 /** expression miner managers for each function-to-synthesize
439 * Notice that for each function-to-synthesize, we enumerate a stream of
440 * candidate solutions, where each of these streams is independent. Thus,
441 * we maintain separate expression miner managers for each of them.
443 * This is used for the sygusRewSynth() option to synthesize new candidate
446 std::map
<Node
, ExpressionMinerManager
> d_exprm
;
449 } // namespace quantifiers
450 } // namespace theory
451 } /* namespace CVC4 */