Introduce ltl_simplifier.

It is limited to negative_normal_form_visitor for now.

* src/ltlvisit/simplify.cc, src/ltlvisit/simplify.hh: New files.
* src/ltlvisit/Makefile.am: Add them.
* src/ltlvisit/nenoform.cc, src/ltlvisit/nenoform.hh: Rewrite
using ltl_simplifier.
This commit is contained in:
Alexandre Duret-Lutz 2011-05-17 19:30:34 +02:00
parent 0caa631c0d
commit 9f7ef5d0c3
5 changed files with 662 additions and 265 deletions

View file

@ -42,6 +42,7 @@ ltlvisit_HEADERS = \
randomltl.hh \
reduce.hh \
simpfg.hh \
simplify.hh \
syntimpl.hh \
tostring.hh \
tunabbrev.hh
@ -63,6 +64,7 @@ libltlvisit_la_SOURCES = \
randomltl.cc \
reduce.cc \
simpfg.cc \
simplify.cc \
syntimpl.cc \
tostring.cc \
tunabbrev.cc

View file

@ -1,4 +1,4 @@
// Copyright (C) 2009, 2010 Laboratoire de Recherche et Développement
// Copyright (C) 2009, 2010, 2011 Laboratoire de Recherche et Développement
// de l'Epita (LRDE).
// Copyright (C) 2003, 2004 Laboratoire d'Informatique de Paris 6 (LIP6),
// département Systèmes Répartis Coopératifs (SRC), Université Pierre
@ -21,279 +21,20 @@
// Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
// 02111-1307, USA.
#include "nenoform.hh"
#include "ltlast/allnodes.hh"
#include <cassert>
#include "simplify.hh"
namespace spot
{
namespace ltl
{
namespace
{
class negative_normal_form_visitor: public visitor
{
public:
negative_normal_form_visitor(bool negated)
: negated_(negated)
{
}
virtual
~negative_normal_form_visitor()
{
}
formula* result() const
{
return result_;
}
void
visit(atomic_prop* ap)
{
formula* f = ap->clone();
if (negated_)
result_ = unop::instance(unop::Not, f);
else
result_ = f;
}
void
visit(constant* c)
{
if (!negated_)
{
result_ = c;
return;
}
switch (c->val())
{
case constant::True:
result_ = constant::false_instance();
return;
case constant::False:
result_ = constant::true_instance();
return;
case constant::EmptyWord:
result_ = unop::instance(unop::Not,
constant::empty_word_instance());
return;
}
/* Unreachable code. */
assert(0);
}
void
visit(unop* uo)
{
formula* f = uo->child();
switch (uo->op())
{
case unop::Not:
result_ = recurse_(f, negated_ ^ true);
return;
case unop::X:
/* !Xa == X!a */
result_ = unop::instance(unop::X, recurse(f));
return;
case unop::F:
/* !Fa == G!a */
result_ = unop::instance(negated_ ? unop::G : unop::F,
recurse(f));
return;
case unop::G:
/* !Ga == F!a */
result_ = unop::instance(negated_ ? unop::F : unop::G,
recurse(f));
return;
case unop::Closure:
result_ = unop::instance(negated_ ?
unop::NegClosure : unop::Closure,
recurse_(f, false));
return;
case unop::NegClosure:
result_ = unop::instance(negated_ ?
unop::Closure : uo->op(),
recurse_(f, false));
return;
/* !Finish(x), is not simplified */
case unop::Finish:
result_ = unop::instance(uo->op(), recurse_(f, false));
if (negated_)
result_ = unop::instance(unop::Not, result_);
return;
}
/* Unreachable code. */
assert(0);
}
void
visit(bunop* bo)
{
// !(a*) is not simplified
result_ = bunop::instance(bo->op(), recurse_(bo->child(), false),
bo->min(), bo->max());
if (negated_)
result_ = unop::instance(unop::Not, result_);
}
void
visit(binop* bo)
{
formula* f1 = bo->first();
formula* f2 = bo->second();
switch (bo->op())
{
case binop::Xor:
/* !(a ^ b) == a <=> b */
result_ = binop::instance(negated_ ? binop::Equiv : binop::Xor,
recurse_(f1, false),
recurse_(f2, false));
return;
case binop::Equiv:
/* !(a <=> b) == a ^ b */
result_ = binop::instance(negated_ ? binop::Xor : binop::Equiv,
recurse_(f1, false),
recurse_(f2, false));
return;
case binop::Implies:
if (negated_)
/* !(a => b) == a & !b */
result_ = multop::instance(multop::And,
recurse_(f1, false),
recurse_(f2, true));
else
result_ = binop::instance(binop::Implies,
recurse(f1), recurse(f2));
return;
case binop::U:
/* !(a U b) == !a R !b */
result_ = binop::instance(negated_ ? binop::R : binop::U,
recurse(f1), recurse(f2));
return;
case binop::R:
/* !(a R b) == !a U !b */
result_ = binop::instance(negated_ ? binop::U : binop::R,
recurse(f1), recurse(f2));
return;
case binop::W:
/* !(a W b) == !a M !b */
result_ = binop::instance(negated_ ? binop::M : binop::W,
recurse(f1), recurse(f2));
return;
case binop::M:
/* !(a M b) == !a W !b */
result_ = binop::instance(negated_ ? binop::W : binop::M,
recurse(f1), recurse(f2));
return;
case binop::UConcat:
/* !(a []-> b) == a<>-> !b */
result_ = binop::instance(negated_ ?
binop::EConcat : binop::UConcat,
recurse_(f1, false), recurse(f2));
return;
case binop::EConcat:
/* !(a <>-> b) == a[]-> !b */
result_ = binop::instance(negated_ ?
binop::UConcat : binop::EConcat,
recurse_(f1, false), recurse(f2));
return;
case binop::EConcatMarked:
/* !(a <>-> b) == a[]-> !b */
result_ = binop::instance(negated_ ?
binop::UConcat :
binop::EConcatMarked,
recurse_(f1, false), recurse(f2));
return;
}
/* Unreachable code. */
assert(0);
}
void
visit(automatop* ao)
{
bool negated = negated_;
negated_ = false;
automatop::vec* res = new automatop::vec;
unsigned aos = ao->size();
for (unsigned i = 0; i < aos; ++i)
res->push_back(recurse(ao->nth(i)));
result_ = automatop::instance(ao->get_nfa(), res, negated);
}
void
visit(multop* mo)
{
multop::type op = mo->op();
/* !(a & b & c) == !a | !b | !c */
/* !(a | b | c) == !a & !b & !c */
if (negated_)
switch (op)
{
case multop::And:
op = multop::Or;
break;
case multop::Or:
op = multop::And;
break;
case multop::Concat:
case multop::Fusion:
case multop::AndNLM:
break;
}
multop::vec* res = new multop::vec;
unsigned mos = mo->size();
switch (op)
{
case multop::And:
case multop::Or:
{
for (unsigned i = 0; i < mos; ++i)
res->push_back(recurse(mo->nth(i)));
result_ = multop::instance(op, res);
break;
}
case multop::Concat:
case multop::Fusion:
case multop::AndNLM:
{
for (unsigned i = 0; i < mos; ++i)
res->push_back(recurse_(mo->nth(i), false));
result_ = multop::instance(op, res);
assert(!negated_);
}
}
}
formula*
recurse_(formula* f, bool negated)
{
return negative_normal_form(f, negated);
}
formula*
recurse(formula* f)
{
return recurse_(f, negated_);
}
protected:
formula* result_;
bool negated_;
};
}
formula*
negative_normal_form(const formula* f, bool negated)
{
if (!negated && f->is_in_nenoform())
return f->clone();
negative_normal_form_visitor v(negated);
const_cast<formula*>(f)->accept(v);
return v.result();
ltl_simplifier s;
return s.negative_normal_form(f, negated);
}
}

View file

@ -1,3 +1,5 @@
// Copyright (C) 2011 Laboratoire de Recherche et Développement de
// l'Epita (LRDE).
// Copyright (C) 2003, 2004 Laboratoire d'Informatique de Paris 6 (LIP6),
// département Systèmes Répartis Coopératifs (SRC), Université Pierre
// et Marie Curie.
@ -23,7 +25,6 @@
# define SPOT_LTLVISIT_NENOFORM_HH
#include "ltlast/formula.hh"
#include "ltlast/visitor.hh"
namespace spot
{

561
src/ltlvisit/simplify.cc Normal file
View file

@ -0,0 +1,561 @@
// Copyright (C) 2011 Laboratoire de Recherche et Developpement de
// l'Epita (LRDE).
//
// This file is part of Spot, a model checking library.
//
// Spot is free software; you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// Spot is distributed in the hope that it will be useful, but WITHOUT
// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
// or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
// License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Spot; see the file COPYING. If not, write to the Free
// Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
// 02111-1307, USA.
#include "simplify.hh"
#include "misc/hash.hh"
#include "tgba/bdddict.hh"
#include "ltlast/allnodes.hh"
#include "ltlast/visitor.hh"
#include <cassert>
namespace spot
{
namespace ltl
{
// The name of this class is public, but not its contents.
class ltl_simplifier_cache
{
typedef Sgi::hash_map<const formula*, const formula*,
ptr_hash<formula> > f2f_map;
typedef Sgi::hash_map<const formula*, bdd,
ptr_hash<formula> > f2b_map;
public:
ltl_simplifier_options options;
~ltl_simplifier_cache()
{
{
f2f_map::iterator i = simplified_.begin();
f2f_map::iterator end = simplified_.end();
while (i != end)
{
f2f_map::iterator old = i++;
old->second->destroy();
old->first->destroy();
}
}
{
f2f_map::iterator i = nenoform_.begin();
f2f_map::iterator end = nenoform_.end();
while (i != end)
{
f2f_map::iterator old = i++;
old->second->destroy();
old->first->destroy();
}
}
{
f2b_map::iterator i = as_bdd_.begin();
f2b_map::iterator end = as_bdd_.end();
while (i != end)
{
f2b_map::iterator old = i++;
old->first->destroy();
}
}
dict_.unregister_all_my_variables(this);
}
ltl_simplifier_cache()
{
}
ltl_simplifier_cache(ltl_simplifier_options opt) : options(opt)
{
}
// Convert a Boolean formula into a BDD for easier comparison.
bdd
as_bdd(const formula* f)
{
// Lookup the result in case it has already been computed.
f2b_map::const_iterator it = as_bdd_.find(f);
if (it != as_bdd_.end())
return it->second;
bdd result = bddfalse;
switch (f->kind())
{
case formula::Constant:
if (f == constant::true_instance())
result = bddtrue;
else if (f == constant::false_instance())
result = bddtrue;
else
assert(!"Unsupported operator");
break;
case formula::AtomicProp:
result = bdd_ithvar(dict_.register_proposition(f, this));
break;
case formula::UnOp:
{
const unop* uo = static_cast<const unop*>(f);
assert(uo->op() == unop::Not);
result = !as_bdd(uo->child());
break;
}
case formula::BinOp:
{
const binop* bo = static_cast<const binop*>(f);
int op = 0;
switch (bo->op())
{
case binop::Xor:
op = bddop_xor;
break;
case binop::Implies:
op = bddop_imp;
break;
case binop::Equiv:
op = bddop_biimp;
break;
default:
assert(!"Unsupported operator");
}
result = bdd_apply(as_bdd(bo->first()), as_bdd(bo->second()), op);
break;
}
case formula::MultOp:
{
const multop* mo = static_cast<const multop*>(f);
switch (mo->op())
{
case multop::And:
{
result = bddtrue;
unsigned s = mo->size();
for (unsigned n = 0; n < s; ++n)
result &= as_bdd(mo->nth(n));
break;
}
case multop::Or:
{
result = bddfalse;
unsigned s = mo->size();
for (unsigned n = 0; n < s; ++n)
result |= as_bdd(mo->nth(n));
break;
}
case multop::Concat:
case multop::Fusion:
case multop::AndNLM:
assert(!"Unsupported operator");
break;
}
break;
}
case formula::BUnOp:
case formula::AutomatOp:
assert(!"Unsupported operator");
break;
}
// Cache the result before returning.
as_bdd_[f->clone()] = result;
return result;
}
const formula*
lookup_nenoform(const formula* f)
{
f2f_map::const_iterator i = nenoform_.find(f);
if (i == nenoform_.end())
return 0;
return i->second->clone();
}
void
cache_nenoform(const formula* orig, const formula* nenoform)
{
nenoform_[orig->clone()] = nenoform->clone();
}
const formula*
lookup_simplified(const formula* f)
{
f2f_map::const_iterator i = simplified_.find(f);
if (i == simplified_.end())
return 0;
return i->second->clone();
}
void
cache_simplified(const formula* orig, const formula* simplified)
{
simplified_[orig->clone()] = simplified->clone();
}
private:
bdd_dict dict_;
f2b_map as_bdd_;
f2f_map simplified_;
f2f_map nenoform_;
};
namespace
{
// Forward declaration.
const formula*
nenoform_recursively(const formula* f,
bool negated,
ltl_simplifier_cache* c);
class negative_normal_form_visitor: public visitor
{
public:
negative_normal_form_visitor(bool negated, ltl_simplifier_cache* c)
: negated_(negated), cache_(c)
{
}
virtual
~negative_normal_form_visitor()
{
}
formula* result() const
{
return result_;
}
void
visit(atomic_prop* ap)
{
formula* f = ap->clone();
if (negated_)
result_ = unop::instance(unop::Not, f);
else
result_ = f;
}
void
visit(constant* c)
{
// Negation of constants is taken care of in the constructor
// of unop::Not, so these cases should be caught by
// nenoform_recursively().
assert(!negated_);
result_ = c;
return;
}
void
visit(unop* uo)
{
formula* f = uo->child();
switch (uo->op())
{
case unop::Not:
// "Not"s should be caught by nenoform_recursively().
assert(!"Not should not occur");
//result_ = recurse_(f, negated_ ^ true);
return;
case unop::X:
/* !Xa == X!a */
result_ = unop::instance(unop::X, recurse(f));
return;
case unop::F:
/* !Fa == G!a */
result_ = unop::instance(negated_ ? unop::G : unop::F,
recurse(f));
return;
case unop::G:
/* !Ga == F!a */
result_ = unop::instance(negated_ ? unop::F : unop::G,
recurse(f));
return;
case unop::Closure:
result_ = unop::instance(negated_ ?
unop::NegClosure : unop::Closure,
recurse_(f, false));
return;
case unop::NegClosure:
result_ = unop::instance(negated_ ?
unop::Closure : uo->op(),
recurse_(f, false));
return;
/* !Finish(x), is not simplified */
case unop::Finish:
result_ = unop::instance(uo->op(), recurse_(f, false));
if (negated_)
result_ = unop::instance(unop::Not, result_);
return;
}
/* Unreachable code. */
assert(0);
}
void
visit(bunop* bo)
{
// !(a*) is not simplified
result_ = bunop::instance(bo->op(), recurse_(bo->child(), false),
bo->min(), bo->max());
if (negated_)
result_ = unop::instance(unop::Not, result_);
}
void
visit(binop* bo)
{
formula* f1 = bo->first();
formula* f2 = bo->second();
switch (bo->op())
{
case binop::Xor:
/* !(a ^ b) == a <=> b */
result_ = binop::instance(negated_ ? binop::Equiv : binop::Xor,
recurse_(f1, false),
recurse_(f2, false));
return;
case binop::Equiv:
/* !(a <=> b) == a ^ b */
result_ = binop::instance(negated_ ? binop::Xor : binop::Equiv,
recurse_(f1, false),
recurse_(f2, false));
return;
case binop::Implies:
if (negated_)
/* !(a => b) == a & !b */
result_ = multop::instance(multop::And,
recurse_(f1, false),
recurse_(f2, true));
else
result_ = binop::instance(binop::Implies,
recurse(f1), recurse(f2));
return;
case binop::U:
/* !(a U b) == !a R !b */
result_ = binop::instance(negated_ ? binop::R : binop::U,
recurse(f1), recurse(f2));
return;
case binop::R:
/* !(a R b) == !a U !b */
result_ = binop::instance(negated_ ? binop::U : binop::R,
recurse(f1), recurse(f2));
return;
case binop::W:
/* !(a W b) == !a M !b */
result_ = binop::instance(negated_ ? binop::M : binop::W,
recurse(f1), recurse(f2));
return;
case binop::M:
/* !(a M b) == !a W !b */
result_ = binop::instance(negated_ ? binop::W : binop::M,
recurse(f1), recurse(f2));
return;
case binop::UConcat:
/* !(a []-> b) == a<>-> !b */
result_ = binop::instance(negated_ ?
binop::EConcat : binop::UConcat,
recurse_(f1, false), recurse(f2));
return;
case binop::EConcat:
/* !(a <>-> b) == a[]-> !b */
result_ = binop::instance(negated_ ?
binop::UConcat : binop::EConcat,
recurse_(f1, false), recurse(f2));
return;
case binop::EConcatMarked:
/* !(a <>-> b) == a[]-> !b */
result_ = binop::instance(negated_ ?
binop::UConcat :
binop::EConcatMarked,
recurse_(f1, false), recurse(f2));
return;
}
/* Unreachable code. */
assert(0);
}
void
visit(automatop* ao)
{
bool negated = negated_;
negated_ = false;
automatop::vec* res = new automatop::vec;
unsigned aos = ao->size();
for (unsigned i = 0; i < aos; ++i)
res->push_back(recurse(ao->nth(i)));
result_ = automatop::instance(ao->get_nfa(), res, negated);
}
void
visit(multop* mo)
{
multop::type op = mo->op();
/* !(a & b & c) == !a | !b | !c */
/* !(a | b | c) == !a & !b & !c */
if (negated_)
switch (op)
{
case multop::And:
op = multop::Or;
break;
case multop::Or:
op = multop::And;
break;
case multop::Concat:
case multop::Fusion:
case multop::AndNLM:
break;
}
multop::vec* res = new multop::vec;
unsigned mos = mo->size();
switch (op)
{
case multop::And:
case multop::Or:
{
for (unsigned i = 0; i < mos; ++i)
res->push_back(recurse(mo->nth(i)));
result_ = multop::instance(op, res);
break;
}
case multop::Concat:
case multop::Fusion:
case multop::AndNLM:
{
for (unsigned i = 0; i < mos; ++i)
res->push_back(recurse_(mo->nth(i), false));
result_ = multop::instance(op, res);
assert(!negated_);
}
}
}
formula*
recurse_(formula* f, bool negated)
{
return const_cast<formula*>(nenoform_recursively(f, negated, cache_));
}
formula*
recurse(formula* f)
{
return recurse_(f, negated_);
}
protected:
formula* result_;
bool negated_;
ltl_simplifier_cache* cache_;
};
const formula*
nenoform_recursively(const formula* f,
bool negated,
ltl_simplifier_cache* c)
{
if (f->kind() == formula::UnOp)
{
const unop* uo = static_cast<const unop*>(f);
if (uo->op() == unop::Not)
{
negated = !negated;
f = uo->child();
}
}
const formula* key = f;
if (negated)
key = unop::instance(unop::Not, f->clone());
const formula* result = c->lookup_nenoform(key);
if (result)
goto done;
if (key->is_in_nenoform()
|| (c->options.nenoform_stop_on_boolean && key->is_boolean()))
{
result = key->clone();
}
else
{
negative_normal_form_visitor v(negated, c);
const_cast<formula*>(f)->accept(v);
result = v.result();
}
c->cache_nenoform(key, result);
done:
if (negated)
key->destroy();
return result;
}
}
const formula*
simplify_recursively(const formula* f,
ltl_simplifier_cache* c)
{
const formula* result = c->lookup_simplified(f);
if (result)
return result;
result = 0;// XXX
c->cache_simplified(f, result);
return result;
}
//////////////////////////////////////////////////////////////////////
// ltl_simplifier
ltl_simplifier::ltl_simplifier()
: cache_(new ltl_simplifier_cache)
{
}
ltl_simplifier::ltl_simplifier(ltl_simplifier_options& opt)
: cache_(new ltl_simplifier_cache(opt))
{
}
ltl_simplifier::~ltl_simplifier()
{
delete cache_;
}
formula*
ltl_simplifier::simplify(const formula* f)
{
return const_cast<formula*>(simplify_recursively(f, cache_));
}
formula*
ltl_simplifier::negative_normal_form(const formula* f, bool negated)
{
return const_cast<formula*>(nenoform_recursively(f, negated, cache_));
}
}
}

92
src/ltlvisit/simplify.hh Normal file
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@ -0,0 +1,92 @@
// Copyright (C) 2011 Laboratoire de Recherche et Developpement de
// l'Epita (LRDE).
//
// This file is part of Spot, a model checking library.
//
// Spot is free software; you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// Spot is distributed in the hope that it will be useful, but WITHOUT
// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
// or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
// License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Spot; see the file COPYING. If not, write to the Free
// Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
// 02111-1307, USA.
#ifndef SPOT_LTLVISIT_SIMPLIFY_HH
# define SPOT_LTLVISIT_SIMPLIFY_HH
#include "ltlast/formula.hh"
#include "bdd.h"
namespace spot
{
namespace ltl
{
class ltl_simplifier_options
{
public:
ltl_simplifier_options()
: reduce_basics(true),
synt_impl(true),
event_univ(true),
containment_checks(false),
containment_checks_stronger(false),
// If true, Boolean subformulae will not be put into
// negative normal form.
nenoform_stop_on_boolean(false)
{
}
bool reduce_basics;
bool synt_impl;
bool event_univ;
bool containment_checks;
bool containment_checks_stronger;
bool nenoform_stop_on_boolean;
};
// fwd declaration to hide technical details.
class ltl_simplifier_cache;
/// \brief Rewrite or simplify \a f in various ways.
/// \ingroup ltl_rewriting
class ltl_simplifier
{
public:
ltl_simplifier();
ltl_simplifier(ltl_simplifier_options& opt);
~ltl_simplifier();
/// Simplify the formula \a f (using options supplied to the constructor).
formula* simplify(const formula* f);
/// Build the negative normal form of formula \a f.
/// All negations of the formula are pushed in front of the
/// atomic propositions.
///
/// \param f The formula to normalize.
/// \param negated If \c true, return the negative normal form of
/// \c !f
///
/// Note that this will not remove abbreviated operators. If you
/// want to remove abbreviations, call spot::ltl::unabbreviate_logic
/// or spot::ltl::unabbreviate_ltl first. (Calling these functions
/// after spot::ltl::negative_normal_form would likely produce a
/// formula which is not in negative normal form.)
formula* negative_normal_form(const formula* f, bool negated = false);
private:
ltl_simplifier_cache* cache_;
};
}
}
#endif // SPOT_LTLVISIT_SIMPLIFY_HH