improve support for LTLf semantics

* spot/twaalgos/remprop.cc, spot/twaalgos/remprop.hh (to_finite): New
function.
* bin/autfilt.cc (--to-finite): Add it.
* doc/org/tut12.org: Update to use it.
* spot/twa/twagraph.cc (purge_dead_states): Also remove false edges.
* spot/parseaut/parseaut.yy: Do not ignore false self-loops, and
add false self-loop on accepting states without successors.
* NEWS: List the above changes.
* tests/core/ltlf.test: New file.
* tests/Makefile.am: Add it.
* tests/core/complete.test: Adjust expected output.

tests/Makefile.am

@@ -272,6 +272,7 @@ TESTS_twa = \
   core/degenscc.test \
   core/randomize.test \
   core/lbttparse.test \
+  core/ltlf.test \
   core/scc.test \
   core/sccdot.test \
   core/sccif.test \

tests/core/complete.test

@@ -1,6 +1,6 @@
 #! /bin/sh
 # -*- coding: utf-8 -*-
-# Copyright (C) 2015-2017 Laboratoire de Recherche et Développement
+# Copyright (C) 2015-2017, 2022 Laboratoire de Recherche et Développement
 # de l'Epita (LRDE).
 #
 # This file is part of Spot, a model checking library.
@@ -236,6 +236,7 @@ properties: deterministic univ-branch
 State: 0 {0}
 [t] 0
 State: 1 {0}
+[f] 1
 [t] 0
 --END--
 EOF
@@ -272,7 +273,8 @@ properties: trans-labels explicit-labels state-acc deterministic
 properties: univ-branch
 --BODY--
 State: 0
-State: 1
+State: 1 {0}
+[f] 1
 --END--
 EOF
 diff out expected

tests/core/ltlf.test

@@ -0,0 +1,175 @@
+#! /bin/sh
+# -*- coding: utf-8 -*-
+# Copyright (C) 2022 Laboratoire de Recherche et Développement 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 3 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+
+. ./defs
+set -e
+
+# ltlfilt --from-ltlf is also tested in ltlfilt.test
+ltlfilt --from-ltlf=A -f 'a & Xa' -f 'a & X[!]a' \
+        -f '(a U b) & (F(c) | F(d & X(0)))' >out
+cat >expected<<EOF
+A & a & X(!A | a) & (A U G!A)
+A & a & X(A & a) & (A U G!A)
+A & (a U (A & b)) & (F(A & c) | F(A & d & X!A)) & (A U G!A)
+EOF
+diff expected out
+
+ltl2tgba -B -F out > out2
+cat >expected2<<EOF
+HOA: v1
+name: "A & a & X(!A | a) & (A U G!A)"
+States: 4
+Start: 1
+AP: 2 "A" "a"
+acc-name: Buchi
+Acceptance: 1 Inf(0)
+properties: trans-labels explicit-labels state-acc deterministic
+properties: very-weak
+--BODY--
+State: 0 {0}
+[!0] 0
+State: 1
+[0&1] 2
+State: 2
+[!0] 0
+[0&1] 3
+State: 3
+[!0] 0
+[0] 3
+--END--
+HOA: v1
+name: "a & X(A & a) & (A U G!A)"
+States: 4
+Start: 2
+AP: 2 "A" "a"
+acc-name: Buchi
+Acceptance: 1 Inf(0)
+properties: trans-labels explicit-labels state-acc deterministic
+properties: very-weak
+--BODY--
+State: 0 {0}
+[!0] 0
+State: 1
+[!0] 0
+[0] 1
+State: 2
+[0&1] 3
+State: 3
+[0&1] 1
+--END--
+HOA: v1
+name: "(a U (A & b)) & (A U G!A) & F((A & c) | (A & d & X!A))"
+States: 5
+Start: 0
+AP: 5 "A" "b" "a" "c" "d"
+acc-name: Buchi
+Acceptance: 1 Inf(0)
+properties: trans-labels explicit-labels state-acc very-weak
+--BODY--
+State: 0
+[0&!1&2&!3] 0
+[0&1&3] 1
+[0&1&!3] 2
+[0&!1&2&3] 3
+[0&1&!3&4] 4
+State: 1
+[0] 1
+[!0] 4
+State: 2
+[0&3] 1
+[0&!3] 2
+[0&!3&4] 4
+State: 3
+[0&1] 1
+[0&!1&2] 3
+State: 4 {0}
+[!0] 4
+--END--
+EOF
+diff expected2 out2
+
+autfilt --to-finite=A out2 >out3
+cat >expected3 <<EOF
+HOA: v1
+States: 3
+Start: 0
+AP: 1 "a"
+acc-name: Buchi
+Acceptance: 1 Inf(0)
+properties: trans-labels explicit-labels state-acc deterministic
+--BODY--
+State: 0
+[0] 1
+State: 1 {0}
+[0] 2
+State: 2 {0}
+[t] 2
+--END--
+HOA: v1
+States: 3
+Start: 1
+AP: 1 "a"
+acc-name: Buchi
+Acceptance: 1 Inf(0)
+properties: trans-labels explicit-labels state-acc deterministic
+--BODY--
+State: 0 {0}
+[t] 0
+State: 1
+[0] 2
+State: 2
+[0] 0
+--END--
+HOA: v1
+States: 5
+Start: 0
+AP: 4 "b" "a" "c" "d"
+acc-name: Buchi
+Acceptance: 1 Inf(0)
+properties: trans-labels explicit-labels state-acc
+--BODY--
+State: 0
+[!0&1&!2] 0
+[0&2] 1
+[0&!2] 2
+[!0&1&2] 3
+[0&!2&3] 4
+State: 1 {0}
+[t] 1
+State: 2
+[2] 1
+[!2] 2
+[!2&3] 4
+State: 3
+[0] 1
+[!0&1] 3
+State: 4 {0}
+[f] 4
+--END--
+EOF
+diff expected3 out3
+
+autfilt out3 > out4
+diff out3 out4
+# Removing the [f] lines should not change anything for autfilt
+grep -v '\[f\]' out4 > out3
+cmp out3 out4 && exit 1 # make sure we did remove something
+autfilt out3 > out4
+diff out4 expected3