ltlcross: add support for alternating automata

* bin/ltlcross.cc: Add an alternation-removal pass, and
adjust CSV output.
* doc/org/ltlcross.org: Update.
* tests/core/ltl3dra.test, tests/core/ltl3ba.test: Add more tests.
* tests/Makefile.am: Add tests/core/ltl3ba.test.
* NEWS: Mention it.

tests/core/ltl3dra.test

@@ -29,7 +29,7 @@ set -e
 (ltl3dra -v) || exit 77
 
 # This used to crash ltlcross because the number of
-# acceptance sets generated was to high.
+# acceptance sets generated was too high.
 ltlcross 'ltl2tgba' 'ltl3dra' -f '(<>((((p0) &&
 (!(<>(p2)))) || ((!(p0)) && (<>(p2)))) U ((<>(((p0) && (!([](((!(p1))
 && ([](p3))) || ((p1) && (!([](p3)))))))) || ((!(p0)) && ([](((!(p1))
@@ -41,3 +41,21 @@ ltlcross 'ltl2tgba' 'ltl3dra' -f '(<>((((p0) &&
 # relabeled p0&p1, and then p0 was unregistered despite being one of
 # the new variables.
 ltldo ltl3dra -f '"a=0" & p0' | grep 'AP: 2.*p0'
+
+# ltl3dra 0.2.2 has a bug were 'ltl3dra -H1 -f true' produce an
+# empty automaton.  ltl3dra 0.2.3 fixes that but introduces another
+# bug where 'ltl3dra -f "!(a <-> Fb)" rejects cycle{!a & b}.
+#
+# # The -H1 option will output alternating automata, so this tests
+# # ltlcross's support in this area.
+# randltl -n 30 2 |
+# ltlcross 'ltl3dra -H1' 'ltl3dra -H2' 'ltl3dra -H3' \
+#          --ignore-execution-failures --ambiguous \
+#          --strength --csv=output.csv
+#
+# # Make sure all lines in output.csv have the same number of comas
+# sed 's/[^,]//g' <output.csv |
+# ( read first
+# while read l; do
+#   test "x$first" = "x$l" || exit 1
+# done)