ltl2tgba_fm: Fix incorrect simplification of promises for M
The bug was reported by Joachim Klein. * src/tgbaalgos/ltl2tgba_fm.cc (translate_dict::register_a_variable): Reduce P(a M b) to P(a & b), not to P(a). * src/tgbatest/ltlcross.test: Test Joachim's formula. * src/tgbatest/ltl2ta.test: Adjust some expected values. * NEWS: Mention the bug.
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Alexandre Duret-Lutz
parent
e7dc62e3c8
commit
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4 changed files with 99 additions and 44 deletions
4
NEWS
4
NEWS
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@ -7,6 +7,10 @@ New in spot 1.2.4a (not yet released)
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* Bug fixes:
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- Fix incorrect simplification of promises in the translation
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of the M operator (you may suffer from the bug even if you do
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not use this operator as some LTL patterns are automatically
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reduced to it).
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- Fix simplification of bounded repetition in SERE formulas.
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- Fix parsing of neverclaims produced by Modella.
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- Fix a memory leak in the little-used conversion from
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@ -254,24 +254,59 @@ namespace spot
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// Similarly
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// a M b = (a R (b&P(a)))
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// (a M b) M c = (a R (b & Pa)) R (c & P(a M b))
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// = (a R (b & Pa)) R (c & P(a))
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// The rules also apply to F:
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// P(F(a)) = P(a)
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again:
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while (const binop* b = is_binop(f))
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// = (a R (b & Pa)) R (c & P(a & b))
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//
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// The code below therefore implement the following
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// rules:
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// P(a U b) = P(b)
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// P(F(a)) = P(a)
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// P(a M b) = P(a & b)
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//
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// The latter rule INCORRECTLY appears as P(a M b)=P(a)
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// in section 3.5 of
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// "LTL translation improvements in Spot 1.0",
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// A. Duret-Lutz. IJCCBS 5(1/2):31-54, March 2014.
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// and was unfortunately implemented this way until Spot
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// 1.2.4. A counterexample is given by the formula
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// G(Fa & ((a M b) U ((c U !d) M d)))
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// that was found by Joachim Klein. Here P((c U !d) M d)
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// and P(c U !d) should not both be simplified to P(!d).
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for (;;)
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{
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binop::type op = b->op();
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if (op == binop::U)
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f = b->second();
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else if (op == binop::M)
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f = b->first();
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if (const binop* b = is_binop(f))
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{
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binop::type op = b->op();
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if (op == binop::U)
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{
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// P(a U b) = P(b)
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f = b->second();
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}
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else if (op == binop::M)
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{
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// P(a M b) = P(a & b)
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const formula* g =
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multop::instance(multop::And,
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b->first()->clone(),
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b->second()->clone());
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int num = dict->register_acceptance_variable(g, this);
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a_set &= bdd_ithvar(num);
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g->destroy();
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return num;
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}
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else
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{
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break;
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}
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}
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else if (const unop* u = is_unop(f, unop::F))
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{
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// P(F(a)) = P(a)
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f = u->child();
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}
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else
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break;
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}
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if (const unop* u = is_unop(f, unop::F))
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{
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f = u->child();
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goto again;
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{
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break;
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}
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}
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int num = dict->register_acceptance_variable(f, this);
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a_set &= bdd_ithvar(num);
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@ -1521,9 +1556,23 @@ namespace spot
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{
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res_ = recurse(node->second(), recurring_);
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bdd f1 = recurse(node->first());
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// r(f1 M f2) = r(f2)(r(f1) + a(f1)X(f1 M f2)) if not recurring
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// r(f1 M f2) = r(f2)(r(f1) + a(f1)) if recurring
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bdd a = bdd_ithvar(dict_.register_a_variable(node->first()));
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// r(f1 M f2) = r(f2)(r(f1) + a(f1&f2)X(f1 M f2)) if not recurring
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// r(f1 M f2) = r(f2)(r(f1) + a(f1&f2)) if recurring
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//
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// Note that the rule above differs from the one given
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// in Figure 2 of
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// "LTL translation improvements in Spot 1.0",
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// A. Duret-Lutz. IJCCBS 5(1/2):31-54, March 2014.
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// Both rules should be OK, but this one is a better fit
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// to the promises simplifications performed in
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// register_a_variable() (see comments in this function).
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// We do not want a U (c M d) to generate two different
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// promises. Generating c&d also makes the output similar
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// to what we would get with the equivalent a U (d U (c & d)).
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//
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// Here we just appear to emit a(f1 M f2) and the conversion
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// to a(f1&f2) is done by register_a_variable().
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bdd a = bdd_ithvar(dict_.register_a_variable(node));
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if (!recurring_)
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a &= bdd_ithvar(dict_.register_next_variable(node));
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res_ &= f1 | a;
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@ -1,5 +1,5 @@
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#!/bin/sh
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# Copyright (C) 2010, 2011, 2012, 2013 Laboratoire de Recherche et
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# Copyright (C) 2010, 2011, 2012, 2013, 2014 Laboratoire de Recherche et
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# Développement de l'Epita (LRDE).
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#
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# This file is part of Spot, a model checking library.
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@ -133,46 +133,46 @@ grep 'states: 21$' stdout
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f="FG((WaitRight4 M (HasRight1 W GWaitLeft0)) M HasLeft4)"
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run 0 ../ltl2tgba -TA -RT -ks -in -R3f -x -DS "$f" >stdout
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grep 'transitions: 450$' stdout
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grep 'states: 38$' stdout
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grep 'transitions: 505$' stdout
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grep 'states: 40$' stdout
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run 0 ../ltl2tgba -TA -RT -ks -lv -R3f -x -DS "$f" >stdout
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grep 'transitions: 551$' stdout
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grep 'states: 40$' stdout
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grep 'transitions: 616$' stdout
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grep 'states: 42$' stdout
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run 0 ../ltl2tgba -TA -RT -ks "$f" >stdout
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grep 'transitions: 424$' stdout
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grep 'states: 31$' stdout
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grep 'transitions: 498$' stdout
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grep 'states: 34$' stdout
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run 0 ../ltl2tgba -TA -RT -ks -sp -lv -in "$f" >stdout
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grep 'transitions: 485$' stdout
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grep 'states: 32$' stdout
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grep 'transitions: 566$' stdout
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grep 'states: 35$' stdout
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run 0 ../ltl2tgba -TA -RT -ks -in -R3 -x -DS "$f" >stdout
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grep 'transitions: 450$' stdout
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grep 'states: 38$' stdout
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grep 'transitions: 505$' stdout
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grep 'states: 40$' stdout
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run 0 ../ltl2tgba -TA -RT -ks -sp -lv -R3 -x -DS "$f" >stdout
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grep 'transitions: 551$' stdout
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grep 'states: 40$' stdout
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grep 'transitions: 616$' stdout
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grep 'states: 42$' stdout
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run 0 ../ltl2tgba -TA -ks -sp -lv -DS "$f" >stdout
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grep 'transitions: 597$' stdout
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grep 'states: 46$' stdout
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grep 'transitions: 819$' stdout
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grep 'states: 56$' stdout
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run 0 ../ltl2tgba -TA -RT -ks -sp -lv "$f" >stdout
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grep 'transitions: 504$' stdout
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grep 'states: 33$' stdout
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grep 'transitions: 585$' stdout
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grep 'states: 36$' stdout
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run 0 ../ltl2tgba -TGTA -RT -ks "$f" >stdout
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grep 'transitions: 527$' stdout
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grep 'states: 32$' stdout
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grep 'transitions: 598$' stdout
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grep 'states: 35$' stdout
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g="G(F(GWaitLeft7 U Idle4) U (WaitLeft2 M IsEating2))"
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@ -1,6 +1,6 @@
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#!/bin/sh
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# -*- coding: utf-8 -*-
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# Copyright (C) 2012, 2013 Laboratoire de Recherche et
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# Copyright (C) 2012, 2013, 2014 Laboratoire de Recherche et
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# Développement de l'Epita (LRDE).
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#
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# This file is part of Spot, a model checking library.
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@ -23,7 +23,13 @@ set -e
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ltl2tgba=../ltl2tgba
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../../bin/randltl -n 100 p1 p2 p3 p4 p5 p6 --tree-size 5..15 |
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(
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# A bug reported by Joachim Klein
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echo 'G(Fa & ((a M b) U ((c U !d) M d)))'
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# Random formulas
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../../bin/randltl -n 100 p1 p2 p3 p4 p5 p6 --tree-size 5..15
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) |
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../../bin/ltlcross --products=2 \
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"$ltl2tgba -t -l %f > %T" \
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"$ltl2tgba -t -l -R3b -r4 %f > %T" \
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@ -47,7 +53,3 @@ ltl2tgba=../ltl2tgba
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"$ltl2tgba -t -taa -r4 %f > %T" \
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"$ltl2tgba -t -taa -r4 -c %f > %T" \
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"$ltl2tgba -t -taa -r4 -R3 -RDS %f > %T"
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# Disabled because too slow, and too big automata produced.
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# "$ltl2tgba -t -lo -r4 %f > %T"
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# "$ltl2tgba -t -lo -R3b -r4 %f > %T" \
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