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/********************* */
/*! \file cegis_unif.cpp
** \verbatim
** Top contributors (to current version):
** Haniel Barbosa
** This file is part of the CVC4 project.
** Copyright (c) 2009-2018 by the authors listed in the file AUTHORS
** in the top-level source directory) and their institutional affiliations.
** All rights reserved. See the file COPYING in the top-level source
** directory for licensing information.\endverbatim
**
** \brief implementation of class for cegis with unification techniques
**/
#include "theory/quantifiers/sygus/cegis_unif.h"
#include "theory/quantifiers/sygus/ce_guided_conjecture.h"
#include "theory/quantifiers/sygus/sygus_unif_rl.h"
#include "theory/quantifiers/sygus/term_database_sygus.h"
using namespace CVC4::kind;
namespace CVC4 {
namespace theory {
namespace quantifiers {
CegisUnif::CegisUnif(QuantifiersEngine* qe, CegConjecture* p)
: SygusModule(qe, p)
{
d_tds = d_qe->getTermDatabaseSygus();
}
CegisUnif::~CegisUnif() {}
bool CegisUnif::initialize(Node n,
const std::vector<Node>& candidates,
std::vector<Node>& lemmas)
{
Trace("cegis-unif") << "Initialize CegisUnif : " << n << std::endl;
Assert(candidates.size() > 0);
if (candidates.size() > 1)
{
return false;
}
d_candidate = candidates[0];
Trace("cegis-unif") << "Initialize unif utility for " << d_candidate
<< "...\n";
d_sygus_unif.initialize(d_qe, d_candidate, d_enums, lemmas);
Assert(!d_enums.empty());
Trace("cegis-unif") << "Initialize " << d_enums.size() << " enumerators for "
<< d_candidate << "...\n";
/* initialize the enumerators */
for (const Node& e : d_enums)
{
d_tds->registerEnumerator(e, d_candidate, d_parent, true);
Node g = d_tds->getActiveGuardForEnumerator(e);
d_enum_to_active_guard[e] = g;
}
return true;
}
void CegisUnif::getTermList(const std::vector<Node>& candidates,
std::vector<Node>& terms)
{
Assert(candidates.size() == 1);
Valuation& valuation = d_qe->getValuation();
for (const Node& e : d_enums)
{
Assert(d_enum_to_active_guard.find(e) != d_enum_to_active_guard.end());
Node g = d_enum_to_active_guard[e];
/* Get whether the active guard for this enumerator is if so, then there may
exist more values for it, and hence we add it to terms. */
Node gstatus = valuation.getSatValue(g);
if (!gstatus.isNull() && gstatus.getConst<bool>())
{
terms.push_back(e);
}
}
}
bool CegisUnif::constructCandidates(const std::vector<Node>& enums,
const std::vector<Node>& enum_values,
const std::vector<Node>& candidates,
std::vector<Node>& candidate_values,
std::vector<Node>& lems)
{
Assert(enums.size() == enum_values.size());
if (enums.empty())
{
return false;
}
unsigned min_term_size = 0;
std::vector<unsigned> enum_consider;
Trace("cegis-unif-enum") << "Register new enumerated values :\n";
for (unsigned i = 0, size = enums.size(); i < size; ++i)
{
Trace("cegis-unif-enum") << " " << enums[i] << " -> " << enum_values[i]
<< std::endl;
unsigned sz = d_tds->getSygusTermSize(enum_values[i]);
if (i == 0 || sz < min_term_size)
{
enum_consider.clear();
min_term_size = sz;
enum_consider.push_back(i);
}
else if (sz == min_term_size)
{
enum_consider.push_back(i);
}
}
/* only consider the enumerators that are at minimum size (for fairness) */
Trace("cegis-unif-enum") << "...register " << enum_consider.size() << " / "
<< enums.size() << std::endl;
NodeManager* nm = NodeManager::currentNM();
for (unsigned i = 0, ecsize = enum_consider.size(); i < ecsize; ++i)
{
unsigned j = enum_consider[i];
Node e = enums[j];
Node v = enum_values[j];
std::vector<Node> enum_lems;
d_sygus_unif.notifyEnumeration(e, v, enum_lems);
/* the lemmas must be guarded by the active guard of the enumerator */
Assert(d_enum_to_active_guard.find(e) != d_enum_to_active_guard.end());
Node g = d_enum_to_active_guard[e];
for (unsigned j = 0, size = enum_lems.size(); j < size; ++j)
{
enum_lems[j] = nm->mkNode(OR, g.negate(), enum_lems[j]);
}
lems.insert(lems.end(), enum_lems.begin(), enum_lems.end());
}
/* build candidate solution */
Assert(candidates.size() == 1);
Node vc = d_sygus_unif.constructSolution();
Trace("cegis-unif-enum") << "... candidate solution :" << vc << "\n";
if (vc.isNull())
{
return false;
}
candidate_values.push_back(vc);
return true;
}
Node CegisUnif::purifyLemma(Node n,
bool ensureConst,
std::vector<Node>& model_guards,
BoolNodePairMap& cache)
{
Trace("cegis-unif-purify") << "PurifyLemma : " << n << "\n";
BoolNodePairMap::const_iterator it = cache.find(BoolNodePair(ensureConst, n));
if (it != cache.end())
{
Trace("cegis-unif-purify") << "... already visited " << n << "\n";
return it->second;
}
/* Recurse */
unsigned size = n.getNumChildren();
Kind k = n.getKind();
bool fapp = k == APPLY_UF && size > 0 && n[0] == d_candidate;
bool childChanged = false;
std::vector<Node> children;
for (unsigned i = 0; i < size; ++i)
{
if (i == 0 && fapp)
{
children.push_back(n[0]);
continue;
}
Node child = purifyLemma(n[i], ensureConst || fapp, model_guards, cache);
children.push_back(child);
childChanged = childChanged || child != n[i];
}
Node nb;
if (childChanged)
{
if (n.hasOperator())
{
children.insert(children.begin(), n.getOperator());
}
nb = NodeManager::currentNM()->mkNode(k, children);
Trace("cegis-unif-purify") << "PurifyLemma : transformed " << n << " into "
<< nb << "\n";
}
else
{
nb = n;
}
/* get model value of non-top level applications of d_candidate */
if (ensureConst && fapp)
{
Node nv = d_parent->getModelValue(nb);
Trace("cegis-unif-purify") << "PurifyLemma : model value for " << nb
<< " is " << nv << "\n";
/* test if different, then update model_guards */
if (nv != nb)
{
Trace("cegis-unif-purify") << "PurifyLemma : adding model eq\n";
model_guards.push_back(
NodeManager::currentNM()->mkNode(EQUAL, nv, nb).negate());
nb = nv;
}
}
nb = Rewriter::rewrite(nb);
/* every non-top level application of function-to-synthesize must be reduced
to a concrete constant */
Assert(!ensureConst || nb.isConst());
Trace("cegis-unif-purify") << "... caching [" << n << "] = " << nb << "\n";
cache[BoolNodePair(ensureConst, n)] = nb;
return nb;
}
void CegisUnif::registerRefinementLemma(const std::vector<Node>& vars,
Node lem,
std::vector<Node>& lems)
{
Node plem;
std::vector<Node> model_guards;
BoolNodePairMap cache;
Trace("cegis-unif") << "Registering lemma at CegisUnif : " << lem << "\n";
/* Make the purified lemma which will guide the unification utility. */
plem = purifyLemma(lem, false, model_guards, cache);
if (!model_guards.empty())
{
model_guards.push_back(plem);
plem = NodeManager::currentNM()->mkNode(OR, model_guards);
}
plem = Rewriter::rewrite(plem);
Trace("cegis-unif") << "Purified lemma : " << plem << "\n";
d_refinement_lemmas.push_back(plem);
/* Notify lemma to unification utility */
d_sygus_unif.addRefLemma(plem);
/* Make the refinement lemma and add it to lems. This lemma is guarded by the
parent's guard, which has the semantics "this conjecture has a solution",
hence this lemma states: if the parent conjecture has a solution, it
satisfies the specification for the given concrete point. */
/* Store lemma for external modules */
lems.push_back(
NodeManager::currentNM()->mkNode(OR, d_parent->getGuard().negate(), lem));
}
} // namespace quantifiers
} // namespace theory
} // namespace CVC4
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