348 lines
7.1 KiB
C++
348 lines
7.1 KiB
C++
// Copyright (C) 2004, 2006, 2007, 2008 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 <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 "ltlvisit/destroy.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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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->ref();
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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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}
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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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formula* f2 = recurse(bo->second());
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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 ((opt_ & Reduce_Eventuality_And_Universality)
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&& ((is_eventual(f2) && ((bo->op()) == binop::U))
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|| (is_universal(f2) && ((bo->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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/* case of implies */
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formula* f1 = recurse(bo->first());
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if (opt_ & Reduce_Syntactic_Implications)
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{
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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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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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destroy(f1);
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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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destroy(f1);
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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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{
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binop* bo = dynamic_cast<binop*>(f2);
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if (bo && bo->op() == binop::U
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&& syntactic_implication(f1, bo->first()))
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{
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result_ = f2;
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destroy(f1);
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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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destroy(f1);
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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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destroy(f1);
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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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{
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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(bo->first(), f1))
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{
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result_ = f2;
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destroy(f1);
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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(bo->op(), f1, f2);
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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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destroy(*f1);
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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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destroy(*f2);
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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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destroy(*j);
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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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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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destroy(prev);
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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 = clone(f);
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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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destroy(f1);
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f1 = negative_normal_form(f2);
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destroy(f2);
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f2 = f1;
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if (opt & Reduce_Basics)
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{
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f1 = basic_reduce(f2);
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destroy(f2);
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f2 = f1;
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}
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if (opt & (Reduce_Syntactic_Implications
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| Reduce_Eventuality_And_Universality))
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{
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reduce_visitor v(opt);
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f2->accept(v);
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f1 = v.result();
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destroy(f2);
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f2 = f1;
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}
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if (opt & (Reduce_Containment_Checks
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| Reduce_Containment_Checks_Stronger))
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{
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formula* f1 =
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reduce_tau03(f2,
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opt & Reduce_Containment_Checks_Stronger);
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destroy(f2);
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f2 = f1;
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}
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f = f2;
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}
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destroy(prev);
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return const_cast<formula*>(f);
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}
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}
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}
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