LAR made smarter with symmetry-based degeneralization

* spot/twaalgos/toparity.cc: here
* spot/twa/acc.hh, spot/twa/acc.cc: compute symmetries of an acceptance
  condition
* tests/python/accparse2.py, tests/python/toparity.py: test it

tests/python/accparse2.py

@@ -1,5 +1,5 @@
 # -*- mode: python; coding: utf-8 -*-
-# Copyright (C) 2015, 2017  Laboratoire de Recherche et Développement
+# Copyright (C) 2015, 2017-2018  Laboratoire de Recherche et Développement
 # de l'Epita
 #
 # This file is part of Spot, a model checking library.
@@ -107,3 +107,10 @@ assert(a.is_streett() == -1)
 a.set_acceptance('(Fin(0)|Inf(1))&(Inf(1)|Fin(0))&(Inf(3)|Fin(2))')
 assert(a.is_rabin() == -1)
 assert(a.is_streett() == 2)
+
+a = spot.acc_code('Inf(0)&Inf(1)&Inf(3) | Fin(0)&(Fin(1)|Fin(3))')
+u = a.symmetries()
+assert u[0] == 0
+assert u[1] == 1
+assert u[2] == 2
+assert u[3] == 1

tests/python/toparity.py

@@ -20,6 +20,21 @@
 
 import spot
 
+a = spot.automaton("""HOA: v1
+States: 1
+Start: 0
+AP: 2 "a" "b"
+Acceptance: 2 Inf(0)|Inf(1)
+--BODY--
+State: 0
+[0&1] 0 {0 1}
+[0&!1] 0 {0}
+[!0&1] 0 {1}
+[!0&!1] 0
+--END--""")
+p = spot.to_parity(a)
+assert spot.are_equivalent(a, p)
+
 for f in spot.randltl(4, 400):
     d = spot.translate(f, "det", "G")
     p = spot.to_parity(d)