Commit 11568666 authored by Alexandre Duret-Lutz's avatar Alexandre Duret-Lutz
Browse files

simplify: remove an incorect SERE simplification

* src/ltlvisit/simplify.cc, doc/tl/tl.tex: Remove the rule.
* src/ltltest/reduc0.test: Add a regression test.
* src/ltltest/reduccmp.test: Adjust test cases for its removal.
* NEWS: Mention it.
parent 88da1ad8
......@@ -181,6 +181,10 @@ New in spot 1.2.5a (not yet released)
* Bug fixes:
- Remove one incorrect simplification rule for PSL discovered
via checks on random formulaes. (The bug was very unlikely
to trigger on non-random formulas, because it requires a SERE
with an entire subexpression that is unsatisfiable.)
- When the automaton resulting from the translation of a positive
formula is deterministic, ltlcross will compute its complement
to perform additional checks against other translations of the
......
......@@ -1570,8 +1570,9 @@ Here are basic the rewritings for the weak closure and its negation:
\nsere{r_1;r_2}&\equiv \nsere{r_1}\AND\nsere{r_2}\quad\text{if~}\varepsilon\VDash r_1\land\varepsilon\VDash r_2\\
\sere{b;r}&\equiV b\AND\X\sere{r}&
\nsere{b;r}&\equiV (\NOT b)\OR\X\nsere{r}\\
\sere{b\STAR{};r}&\equiv b\W\sere{r}&
\nsere{b\STAR{};r}&\equiv (\NOT b)\M\nsere{r}\\
% These two would be correct only if $r$ is satisfiable.
% \sere{b\STAR{};r}&\equiv b\W\sere{r}&
% \nsere{b\STAR{};r}&\equiv (\NOT b)\M\nsere{r}\\
\sere{b\STAR{\mvar{i}..\mvar{j}};r}&\equiV \underbrace{b\AND \X(b\ldots}_{\mathclap{i\text{~occurences of~}b}}\AND\X\sere{b\STAR{\mvar{0}..\mvar{j-i}}\CONCAT r})&
\nsere{b\STAR{\mvar{i}..\mvar{j}};r}&\equiV \underbrace{(\NOT b)\OR \X((\NOT b)\ldots}_{\mathclap{i\text{~occurences of~}\NOT b}}\OR\X\nsere{b\STAR{\mvar{0}..\mvar{j-i}}\CONCAT r}) \\
\sere{b\STAR{\mvar{i}..\mvar{j}}}&\equiV \underbrace{b\AND \X(b\AND \X(\ldots b))}_{i\text{~occurences of~}b}&
......
#! /bin/sh
# Copyright (C) 2013 Laboratoire de Recherche et
# Copyright (C) 2013, 2014 Laboratoire de Recherche et
# Développement de l'Epita (LRDE).
#
# This file is part of Spot, a model checking library.
......@@ -24,3 +24,9 @@ set -e
run 0 ../reduc 0 'XFa & FXa' 'XFa'
run 0 ../reduc 0 '(Xf W 0) | X(f W 0)' 'XGf'
# Two incorrect reductions. Those used
# to reduce respectively to a W (b && !b) and !a M (b || !b).
# But both are wrong. The reduction {a*;r} = a W r seems only
# valid if r has a non-empty language.
run 0 ../reduc 0 '{a[*];{b && !b}}'
run 0 ../reduc 0 '!{a[*];{b && !b}}'
......@@ -25,6 +25,7 @@
# Check LTL reductions
. ./defs || exit 1
set -e
cat >common.txt <<EOF
......@@ -375,14 +376,14 @@ G(GFc|GFd|FGe|FGf), F(GF(c|d)|Ge|Gf)
{a:b*:c:d*}<>->e, a & ((c & (e M d)) M b)
{a|b*|c|d*}<>->e, ((a | c) & e) | (e M b) | (e M d)
{{[*0]|a};b;{[*0]|a};c;e[*]}<>->f, {{[*0]|a};b;{[*0]|a}}<>->X(c&(f|X(f M e)))
{a;b[*];c[*];e;f*}, a & X(b W (c W e))
{a;b*;(a* && (b;c));c*}, a & X(b W {a[*] && {b;c}})
{a;b[*];c[*];e;f*}, a & X({b*;c*;e})
{a;b*;(a* && (b;c));c*}, a & X({b*;(a* && (b;c))})
{a;a;b[*2..];b}, a & X(a & X(b & X(b & Xb)))
!{a;a;b[*2..];b}, !a | X(!a | X(!b | X(!b | X!b)))
!{a;b[*];c[*];e;f*}, !a | X(!b M (!c M !e))
!{a;b*;(a* && (b;c));c*}, !a | X(!b M !{a[*] && {b;c}})
{(a;c*;d)|(b;c)}, (a & X(c W d)) | (b & Xc)
!{(a;c*;d)|(b;c)}, (X(!c M !d) | !a) & (X!c | !b)
!{a;c[*];e;f*}, !a | X!{c[*];e}
!{a;b*;(a* && (b;c));c*}, !a | X(!{b*;(a* && (b;c))})
{(a;c*;d)|(b;c)}, (a & X{c*;d}) | (b & Xc)
!{(a;c*;d)|(b;c)}, (X(!{c*;d}) | !a) & (X!c | !b)
(Xc R b) & (Xc W 0), b & XGc
{{c*|1}[*0..1]}<>-> v, {{c[+]|1}[*0..1]}<>-> v
{{b*;c*}[*3..5]}<>-> v, {{b*;c*}[*0..5]} <>-> v
......
......@@ -1592,10 +1592,10 @@ namespace spot
// Some term does not accept the empty word.
unsigned end = mo->size() - 1;
// {b₁;b₂;b₃*;e₁;f₁;e₂;f₂;e₂;e₃;e₄}
// = b₁&X(b₂&X(b₃ W {e₁;f₁;e₂;f₂}))
// !{b₁;b₂;b₃*;e₁;f₁;e₂;f₂;e₂;e₃;e₄}
// = !b₁|X(!b₂|X(!b₃ M !{e₁;f₁;e₂;f₂}))
// {b₁;b₂;e₁;f₁;e₂;f₂;e₂;e₃;e₄}
// = b₁&X(b₂&X({e₁;f₁;e₂;f₂}))
// !{b₁;b₂;e₁;f₁;e₂;f₂;e₂;e₃;e₄}
// = !b₁|X(!b₂|X(!{e₁;f₁;e₂;f₂}))
// if e denotes a term that accepts [*0]
// and b denotes a Boolean formula.
while (mo->nth(end)->accepts_eword())
......@@ -1604,9 +1604,7 @@ namespace spot
while (start <= end)
{
const formula* r = mo->nth(start);
const bunop* es = is_KleenStar(r);
if ((r->is_boolean() && !opt_.reduce_size_strictly)
|| (es && es->child()->is_boolean()))
if (r->is_boolean() && !opt_.reduce_size_strictly)
++start;
else
break;
......@@ -1652,21 +1650,6 @@ namespace spot
tail =
multop::instance(multop::And, e, tail);
}
// {b*;f} = b W {f}
// !{b*;f} = !b M !{f}
else
{
const bunop* es = is_KleenStar(e);
assert(es);
const formula* c = es->child()->clone();
if (doneg)
tail =
binop::instance(binop::M,
unop::instance(unop::Not, c),
tail);
else
tail = binop::instance(binop::W, c, tail);
}
}
mo->destroy();
result_ = recurse_destroy(tail);
......
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