simplify_acc: loop over the simplifications

* spot/twaalgos/cleanacc.cc (simplify_acceptance_here): Run the
simplifications in a loop until the condition does not change anymore.
* tests/python/simplacc.py, tests/core/accsimpl.test,
tests/core/remfin.test, tests/python/merge.py,
tests/python/simplacc.py, tests/python/toparity.py: Update expected
results.
* tests/python/automata.ipynb: Update the failing example to a more
interesting one, matching the one in doc/org/autfilt.org.

spot/twaalgos/cleanacc.cc

@@ -617,20 +617,20 @@ namespace spot
 
   twa_graph_ptr simplify_acceptance_here(twa_graph_ptr aut)
   {
-    cleanup_acceptance_here(aut, false);
+    for (;;)
-    merge_identical_marks_here(aut);
-    if (!aut->acc().is_generalized_buchi())
       {
+        cleanup_acceptance_here(aut, false);
+        merge_identical_marks_here(aut);
+        if (aut->acc().is_generalized_buchi())
+          break;
+        acc_cond::acc_code old = aut->get_acceptance();
         simplify_complementary_marks_here(aut);
         fuse_marks_here(aut);
+        aut->set_acceptance(aut->acc().unit_propagation());
+        if (old == aut->get_acceptance())
+          break;
       }
     cleanup_acceptance_here(aut, true);
-    auto prop_cond = aut->acc().unit_propagation();
-    if (prop_cond != aut->acc())
-    {
-      aut->set_acceptance(prop_cond);
-      cleanup_acceptance_here(aut, true);
-    }
     return aut;
   }
 

tests/core/accsimpl.test

@@ -72,4 +72,4 @@ State: 0
 --END--
 EOF
 autcross --language-preserved 'autfilt --simplify-acc' -F frenkin
-test 1,4,2 = "`autfilt --simplify-acc frenkin --stats=%s,%e,%a`"
+test 1,4,1 = "`autfilt --simplify-acc frenkin --stats=%s,%e,%a`"

tests/core/remfin.test

@@ -313,27 +313,25 @@ State: 2 {0}
 [!1] 2
 --END--
 HOA: v1
-States: 4
+States: 3
 Start: 0
 AP: 2 "a" "b"
-Acceptance: 4 Inf(0) | Inf(3) | (Inf(1)&Inf(2))
+acc-name: Buchi
+Acceptance: 1 Inf(0)
 properties: trans-labels explicit-labels trans-acc
 --BODY--
 State: 0
-[t] 0 {2 3}
+[t] 0 {0}
-[0] 1 {2 3}
+[0] 1 {0}
-[!0] 2 {2 3}
+[!0] 2 {0}
 State: 1
-[1] 0 {2}
+[1] 0 {0}
-[0&1] 1 {2}
+[0&1] 1 {0}
-[!0&1] 2 {1 2}
+[!0&1] 2 {0}
 State: 2
 [!1] 0
-[0&!1] 1
+[0&!1] 1 {0}
-[!0&!1] 2
+[!0&!1] 2 {0}
-[!0&!1] 3
-State: 3
-[!0&!1] 3 {0}
 --END--
 HOA: v1
 States: 3
@@ -915,7 +913,7 @@ State: 2 {0}
 [!1] 2
 --END--
 HOA: v1
-States: 4
+States: 3
 Start: 0
 AP: 2 "a" "b"
 acc-name: Buchi
@@ -927,16 +925,13 @@ State: 0
 [0] 1 {0}
 [!0] 2 {0}
 State: 1
-[1] 0
+[1] 0 {0}
-[0&1] 1
+[0&1] 1 {0}
 [!0&1] 2 {0}
 State: 2
 [!1] 0
-[0&!1] 1
+[0&!1] 1 {0}
-[!0&!1] 2
+[!0&!1] 2 {0}
-[!0&!1] 3
-State: 3
-[!0&!1] 3 {0}
 --END--
 HOA: v1
 States: 3

tests/python/merge.py

@@ -1,6 +1,6 @@
 #!/usr/bin/python3
 # -*- mode: python; coding: utf-8 -*-
-# Copyright (C) 2017 Laboratoire de Recherche et Développement de
+# Copyright (C) 2017, 2020 Laboratoire de Recherche et Développement de
 # l'EPITA.
 #
 # This file is part of Spot, a model checking library.
@@ -78,8 +78,7 @@ assert hoa == """HOA: v1
 States: 3
 Start: 0
 AP: 2 "a" "b"
-acc-name: parity min even 2
+Acceptance: 2 Fin(1) | Inf(0)
-Acceptance: 2 Inf(0) | Fin(1)
 properties: trans-labels explicit-labels trans-acc
 --BODY--
 State: 0

tests/python/simplacc.py

@@ -57,23 +57,28 @@ for a in auts:
     b = spot.simplify_acceptance(a)
     assert b.equivalent_to(a)
     res.append(str(b.get_acceptance()))
+    c = spot.simplify_acceptance(b)
+    assert b.get_acceptance() == c.get_acceptance()
 
     a.set_acceptance(a.num_sets(), a.get_acceptance().complement())
     b = spot.simplify_acceptance(a)
     assert b.equivalent_to(a)
     res.append(str(b.get_acceptance()))
+    c = spot.simplify_acceptance(b)
+    assert b.get_acceptance() == c.get_acceptance()
+
 
 assert res == [
    'Inf(0)',
    'Fin(0)',
-   'Inf(1) & Fin(0)',
+   'Fin(0) & Inf(1)',
    'Fin(1) | Inf(0)',
-   'Inf(1) & (Fin(0) | Inf(2))',
+   '(Fin(0) | Inf(2)) & Inf(1)',
    'Fin(1) | (Fin(2) & Inf(0))',
    '(Fin(1) | Inf(2)) & Inf(0)',
    'Fin(0) | (Fin(2) & Inf(1))',
    '((Fin(1) | Inf(2)) & Inf(5)) | (Fin(0) & (Fin(1) | (Fin(3) & Inf(4))))',
    '(Fin(5) | (Fin(2) & Inf(1))) & (Inf(0) | ((Fin(4) | Inf(3)) & Inf(1)))',
-   'Inf(1) | Inf(0)',
+   'Inf(0)',
-   'Fin(1) & Fin(0)',
+   'Fin(0)',
    ]

tests/python/toparity.py

@@ -288,7 +288,7 @@ State: 4
 [0&!1] 4
 [0&1] 4 {1 2 4}
 --END--
-"""), [9, 6, 7, 7, 6, 6, 6])
+"""), [9, 6, 6, 6, 7, 6, 6])
 
 test(spot.automaton("""
 HOA: v1