1878bfd0fc
* src/ltlvisit/reduce.cc (reduce_visitor): Always reduce "a M b" to "a & b" if "a" is a pure eventual formula, remove the constraint on "b". * src/ltltest/reduccmp.test: Add two tests.
638 lines
13 KiB
C++
638 lines
13 KiB
C++
// Copyright (C) 2008, 2009, 2010, 2011 Laboratoire de Recherche et
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// Développement de l'Epita (LRDE).
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// Copyright (C) 2004, 2006, 2007 Laboratoire d'Informatique de
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// Paris 6 (LIP6), département Systèmes Répartis Coopératifs (SRC),
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// Université Pierre et Marie Curie.
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//
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// This file is part of Spot, a model checking library.
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//
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// Spot is free software; you can redistribute it and/or modify it
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// under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 2 of the License, or
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// (at your option) any later version.
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//
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// Spot is distributed in the hope that it will be useful, but WITHOUT
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// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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// or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
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// License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with Spot; see the file COPYING. If not, write to the Free
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// Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
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// 02111-1307, USA.
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#include "reduce.hh"
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#include "basicreduce.hh"
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#include "syntimpl.hh"
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#include "ltlast/allnodes.hh"
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#include <cassert>
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#include "lunabbrev.hh"
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#include "simpfg.hh"
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#include "nenoform.hh"
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#include "contain.hh"
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namespace spot
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{
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namespace ltl
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{
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namespace
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{
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typedef union
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{
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unsigned v;
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struct is_struct
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{
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bool eventual:1;
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bool universal:1;
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} is;
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} eu_info;
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static unsigned recurse_eu(const formula* f);
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class eventual_universal_visitor: public const_visitor
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{
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public:
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eventual_universal_visitor()
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{
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}
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virtual
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~eventual_universal_visitor()
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{
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}
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bool
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is_eventual() const
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{
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return ret_.is.eventual;
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}
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bool
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is_universal() const
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{
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return ret_.is.universal;
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}
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unsigned
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eu() const
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{
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return ret_.v;
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}
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void
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visit(const atomic_prop*)
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{
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ret_.v = 0;
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}
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void
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visit(const constant*)
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{
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ret_.v = 0;
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}
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void
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visit(const unop* uo)
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{
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const formula* f1 = uo->child();
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if (uo->op() == unop::F)
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{
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ret_.v = recurse_eu(f1);
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ret_.is.eventual = true;
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return;
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}
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if (uo->op() == unop::G)
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{
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ret_.v = recurse_eu(f1);
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ret_.is.universal = true;
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return;
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}
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ret_.v = 0;
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return;
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}
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void
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visit(const binop* bo)
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{
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const formula* f1 = bo->first();
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const formula* f2 = bo->second();
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// Beware: (f U g) is purely eventual if both operands
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// are purely eventual, unlike in the proceedings of
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// Concur'00. (The revision of the paper available at
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// http://www.bell-labs.com/project/TMP/ is fixed.) See
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// also http://arxiv.org/abs/1011.4214 for a discussion
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// about this problem. (Which we fixed in 2005 thanks
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// to LBTT.)
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// This means that we can use the following case to handle
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// all cases of (f U g), (f R g), (f W g), (f M g) for
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// universality and eventuality.
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ret_.v = recurse_eu(f1) & recurse_eu(f2);
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// we are left with the case where U, R, W, or M are actually
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// used to represent F or G.
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switch (bo->op())
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{
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case binop::Xor:
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case binop::Equiv:
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case binop::Implies:
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return;
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case binop::U:
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if (f1 == constant::true_instance())
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ret_.is.eventual = true;
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return;
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case binop::W:
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if (f2 == constant::true_instance())
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ret_.is.eventual = true;
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return;
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case binop::R:
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if (f1 == constant::false_instance())
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ret_.is.universal = true;
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return;
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case binop::M:
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if (f2 == constant::false_instance())
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ret_.is.universal = true;
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return;
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}
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/* Unreachable code. */
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assert(0);
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}
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void
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visit(const automatop*)
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{
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assert(0);
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}
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void
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visit(const multop* mo)
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{
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unsigned mos = mo->size();
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assert(mos != 0);
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ret_.v = recurse_eu(mo->nth(0));
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for (unsigned i = 1; i < mos && ret_.v != 0; ++i)
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ret_.v &= recurse_eu(mo->nth(i));
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}
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private:
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eu_info ret_;
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};
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static unsigned
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recurse_eu(const formula* f)
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{
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eventual_universal_visitor v;
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const_cast<formula*>(f)->accept(v);
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return v.eu();
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}
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/////////////////////////////////////////////////////////////////////////
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class reduce_visitor: public visitor
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{
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public:
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reduce_visitor(int opt)
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: opt_(opt)
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{
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}
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virtual ~reduce_visitor()
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{
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}
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formula*
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result() const
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{
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return result_;
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}
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void
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visit(atomic_prop* ap)
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{
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formula* f = ap->clone();
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result_ = f;
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}
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void
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visit(constant* c)
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{
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result_ = c;
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}
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void
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visit(unop* uo)
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{
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result_ = recurse(uo->child());
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switch (uo->op())
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{
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case unop::Not:
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result_ = unop::instance(unop::Not, result_);
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return;
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case unop::X:
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result_ = unop::instance(unop::X, result_);
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return;
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case unop::F:
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/* If f is a pure eventuality formula then F(f)=f. */
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if (!(opt_ & Reduce_Eventuality_And_Universality)
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|| !is_eventual(result_))
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result_ = unop::instance(unop::F, result_);
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return;
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case unop::G:
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/* If f is a pure universality formula then G(f)=f. */
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if (!(opt_ & Reduce_Eventuality_And_Universality)
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|| !is_universal(result_))
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result_ = unop::instance(unop::G, result_);
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return;
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case unop::Finish:
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result_ = unop::instance(unop::Finish, result_);
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return;
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}
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/* Unreachable code. */
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assert(0);
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}
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void
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visit(binop* bo)
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{
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binop::type op = bo->op();
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formula* f2 = recurse(bo->second());
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eu_info f2i = { recurse_eu(f2) };
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if (opt_ & Reduce_Eventuality_And_Universality)
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{
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/* If b is a pure eventuality formula then a U b = b.
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If b is a pure universality formula a R b = b. */
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if ((f2i.is.eventual && (op == binop::U))
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|| (f2i.is.universal && (op == binop::R)))
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{
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result_ = f2;
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return;
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}
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}
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formula* f1 = recurse(bo->first());
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eu_info f1i = { recurse_eu(f1) };
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if (opt_ & Reduce_Eventuality_And_Universality)
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{
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/* If a is a pure eventuality formula then a M b = a & b.
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If a is a pure universality formula a W b = a|b. */
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if (f1i.is.eventual && (op == binop::M))
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{
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result_ = multop::instance(multop::And, f1, f2);
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return;
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}
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if (f1i.is.universal && (op == binop::W))
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{
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result_ = multop::instance(multop::Or, f1, f2);
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return;
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}
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}
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/* case of implies */
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if (opt_ & Reduce_Syntactic_Implications)
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{
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switch (op)
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{
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case binop::Xor:
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case binop::Equiv:
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case binop::Implies:
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break;
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case binop::U:
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/* a < b => a U b = b */
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if (syntactic_implication(f1, f2))
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{
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result_ = f2;
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f1->destroy();
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return;
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}
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/* !b < a => a U b = Fb */
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if (syntactic_implication_neg(f2, f1, false))
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{
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result_ = unop::instance(unop::F, f2);
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f1->destroy();
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return;
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}
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/* a < b => a U (b U c) = (b U c) */
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/* a < b => a U (b W c) = (b W c) */
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{
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binop* bo = dynamic_cast<binop*>(f2);
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if (bo && (bo->op() == binop::U || bo->op() == binop::W)
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&& syntactic_implication(f1, bo->first()))
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{
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result_ = f2;
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f1->destroy();
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return;
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}
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}
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break;
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case binop::R:
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/* b < a => a R b = b */
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if (syntactic_implication(f2, f1))
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{
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result_ = f2;
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f1->destroy();
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return;
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}
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/* b < !a => a R b = Gb */
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if (syntactic_implication_neg(f2, f1, true))
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{
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result_ = unop::instance(unop::G, f2);
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f1->destroy();
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return;
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}
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/* b < a => a R (b R c) = b R c */
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/* b < a => a R (b M c) = b M c */
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{
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binop* bo = dynamic_cast<binop*>(f2);
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if (bo && (bo->op() == binop::R || bo->op() == binop::M)
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&& syntactic_implication(bo->first(), f1))
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{
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result_ = f2;
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f1->destroy();
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return;
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}
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}
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/* a < b => a R (b R c) = a R c */
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{
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binop* bo = dynamic_cast<binop*>(f2);
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if (bo && bo->op() == binop::R
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&& syntactic_implication(f1, bo->first()))
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{
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result_ = binop::instance(binop::R, f1,
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bo->second()->clone());
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f2->destroy();
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return;
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}
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}
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break;
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case binop::W:
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/* a < b => a W b = b */
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if (syntactic_implication(f1, f2))
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{
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result_ = f2;
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f1->destroy();
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return;
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}
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/* !b < a => a W b = 1 */
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if (syntactic_implication_neg(f2, f1, false))
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{
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result_ = constant::true_instance();
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f1->destroy();
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f2->destroy();
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return;
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}
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/* a < b => a W (b W c) = (b W c) */
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{
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binop* bo = dynamic_cast<binop*>(f2);
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if (bo && bo->op() == binop::W
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&& syntactic_implication(f1, bo->first()))
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{
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result_ = f2;
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f1->destroy();
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return;
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}
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}
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break;
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case binop::M:
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/* b < a => a M b = b */
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if (syntactic_implication(f2, f1))
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{
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result_ = f2;
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f1->destroy();
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return;
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}
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/* b < !a => a M b = 0 */
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if (syntactic_implication_neg(f2, f1, true))
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{
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result_ = constant::false_instance();
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f1->destroy();
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f2->destroy();
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return;
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}
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/* b < a => a M (b M c) = b M c */
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{
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binop* bo = dynamic_cast<binop*>(f2);
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if (bo && bo->op() == binop::M
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&& syntactic_implication(bo->first(), f1))
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{
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result_ = f2;
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f1->destroy();
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return;
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}
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}
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/* a < b => a M (b M c) = a M c */
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/* a < b => a M (b R c) = a M c */
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{
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binop* bo = dynamic_cast<binop*>(f2);
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if (bo && (bo->op() == binop::M || bo->op() == binop::R)
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&& syntactic_implication(f1, bo->first()))
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{
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result_ = binop::instance(binop::M, f1,
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bo->second()->clone());
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f2->destroy();
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return;
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}
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}
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break;
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}
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}
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result_ = binop::instance(op, f1, f2);
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}
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void
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visit(automatop*)
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{
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assert(0);
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}
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void
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visit(multop* mo)
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{
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unsigned mos = mo->size();
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multop::vec* res = new multop::vec;
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for (unsigned i = 0; i < mos; ++i)
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res->push_back(recurse(mo->nth(i)));
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if (opt_ & Reduce_Syntactic_Implications)
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{
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bool removed = true;
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multop::vec::iterator f1;
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multop::vec::iterator f2;
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while (removed)
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{
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removed = false;
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f2 = f1 = res->begin();
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++f1;
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while (f1 != res->end())
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{
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assert(f1 != f2);
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// a < b => a + b = b
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// a < b => a & b = a
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if ((syntactic_implication(*f1, *f2) && // f1 < f2
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(mo->op() == multop::Or)) ||
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((syntactic_implication(*f2, *f1)) && // f2 < f1
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(mo->op() == multop::And)))
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{
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// We keep f2
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(*f1)->destroy();
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res->erase(f1);
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removed = true;
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break;
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}
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else if ((syntactic_implication(*f2, *f1) && // f2 < f1
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(mo->op() == multop::Or)) ||
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((syntactic_implication(*f1, *f2)) && // f1 < f2
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(mo->op() == multop::And)))
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{
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// We keep f1
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(*f2)->destroy();
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res->erase(f2);
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removed = true;
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break;
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}
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else
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++f1;
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}
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}
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/* f1 < !f2 => f1 & f2 = false
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!f1 < f2 => f1 | f2 = true */
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for (f1 = res->begin(); f1 != res->end(); f1++)
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for (f2 = res->begin(); f2 != res->end(); f2++)
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if (f1 != f2 &&
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syntactic_implication_neg(*f1, *f2,
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mo->op() != multop::Or))
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{
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for (multop::vec::iterator j = res->begin();
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j != res->end(); j++)
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(*j)->destroy();
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res->clear();
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delete res;
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if (mo->op() == multop::Or)
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result_ = constant::true_instance();
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else
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result_ = constant::false_instance();
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return;
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}
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}
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if (!res->empty())
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{
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result_ = multop::instance(mo->op(), res);
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return;
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}
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assert(0);
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}
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formula*
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recurse(formula* f)
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{
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return reduce(f, opt_);
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}
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protected:
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formula* result_;
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int opt_;
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};
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} // anonymous
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|
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formula*
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reduce(const formula* f, int opt)
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{
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formula* f1;
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formula* f2;
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formula* prev = 0;
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int n = 0;
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while (f != prev)
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{
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++n;
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assert(n < 100);
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if (prev)
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{
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prev->destroy();
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prev = const_cast<formula*>(f);
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}
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else
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{
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prev = f->clone();
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}
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f1 = unabbreviate_logic(f);
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f2 = simplify_f_g(f1);
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f1->destroy();
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f1 = negative_normal_form(f2);
|
|
f2->destroy();
|
|
f2 = f1;
|
|
|
|
if (opt & Reduce_Basics)
|
|
{
|
|
f1 = basic_reduce(f2);
|
|
f2->destroy();
|
|
f2 = f1;
|
|
}
|
|
|
|
if (opt & (Reduce_Syntactic_Implications
|
|
| Reduce_Eventuality_And_Universality))
|
|
{
|
|
reduce_visitor v(opt);
|
|
f2->accept(v);
|
|
f1 = v.result();
|
|
f2->destroy();
|
|
f2 = f1;
|
|
}
|
|
|
|
|
|
if (opt & (Reduce_Containment_Checks
|
|
| Reduce_Containment_Checks_Stronger))
|
|
{
|
|
formula* f1 =
|
|
reduce_tau03(f2,
|
|
opt & Reduce_Containment_Checks_Stronger);
|
|
f2->destroy();
|
|
f2 = f1;
|
|
}
|
|
f = f2;
|
|
}
|
|
prev->destroy();
|
|
return const_cast<formula*>(f);
|
|
}
|
|
|
|
bool
|
|
is_eventual(const formula* f)
|
|
{
|
|
eventual_universal_visitor v;
|
|
const_cast<formula*>(f)->accept(v);
|
|
return v.is_eventual();
|
|
}
|
|
|
|
bool
|
|
is_universal(const formula* f)
|
|
{
|
|
eventual_universal_visitor v;
|
|
const_cast<formula*>(f)->accept(v);
|
|
return v.is_universal();
|
|
}
|
|
}
|
|
}
|