translate: add ltl-split option

* spot/twaalgos/translate.cc, spot/twaalgos/translate.hh: Build
automata with generic acceptance by doing product of automata for
smaller subformulas.
* bin/spot-x.cc: Mention ltl-split.
* NEWS: Mention the change, and show some results.
* tests/core/genltl.test, tests/python/_product_susp.ipynb,
tests/python/highlighting.ipynb: Adjust test cases.
* doc/org/ltl2tgba.org: Update.
* tests/core/gragsa.test: Add another formula to cover more
code.

tests/core/genltl.test

@@ -183,29 +183,29 @@ cat >exp<<EOF
 "ms-example=4,2",10
 "ms-example=4,3",11
 "ms-example=4,4",12
-"ms-phi-r=0",2
-"ms-phi-r=1",16
-"ms-phi-r=2",29
-"ms-phi-s=0",5
-"ms-phi-s=1",8
-"ms-phi-s=2",497
+"ms-phi-r=0",1
+"ms-phi-r=1",1
+"ms-phi-r=2",1
+"ms-phi-s=0",1
+"ms-phi-s=1",1
+"ms-phi-s=2",1
 "ms-phi-h=0",1
-"ms-phi-h=1",3
-"ms-phi-h=2",7
-"ms-phi-h=3",15
-"ms-phi-h=4",31
+"ms-phi-h=1",2
+"ms-phi-h=2",5
+"ms-phi-h=3",19
+"ms-phi-h=4",83
 "gf-equiv=0",1
-"gf-equiv=1",4
-"gf-equiv=2",8
-"gf-equiv=3",21
-"gf-equiv=4",81
-"gf-equiv=5",431
+"gf-equiv=1",1
+"gf-equiv=2",1
+"gf-equiv=3",1
+"gf-equiv=4",1
+"gf-equiv=5",1
 "gf-implies=0",1
-"gf-implies=1",5
-"gf-implies=2",12
-"gf-implies=3",41
-"gf-implies=4",186
-"gf-implies=5",1047
+"gf-implies=1",1
+"gf-implies=2",1
+"gf-implies=3",1
+"gf-implies=4",1
+"gf-implies=5",1
 "gf-equiv-xn=1",2
 "gf-equiv-xn=2",4
 "gf-equiv-xn=3",8

tests/core/gragsa.test

@@ -1,6 +1,6 @@
 #!/bin/sh
 # -*- coding: utf-8 -*-
-# Copyright (C) 2016 Laboratoire de Recherche
+# Copyright (C) 2016, 2018 Laboratoire de Recherche
 # et Développement de l'Epita (LRDE).
 #
 # This file is part of Spot, a model checking library.
@@ -21,8 +21,10 @@
 . ./defs
 set -e
 
+# formula 'XX((Fa|Gb)&FGc)' tests the X removal of the ltl-split path
+
 randltl -n 100 p1 p2 p3 --tree-size 5..15 --seed=200 |
-ltlcross --timeout=60 \
+ltlcross -F- -f 'XX((Fa|Gb)&FGc)' --timeout=60 \
 "ltl2tgba %f > %T" \
 "ltl2tgba -G -D %f > %T" \
 "ltl2tgba -G -D %f | autfilt --gsa=unique-fin > %T" \