simplify_acceptance: Use color inclusions to simplify a condition

This fixes #406.

* spot/twaalgos/cleanacc.cc: Add the simplification.
* tests/core/remfin.test, tests/python/automata.ipynb,
tests/python/remfin.py: Update tests.
* tests/python/simplacc.py: Update and add tests.

spot/twaalgos/cleanacc.cc

@@ -613,6 +613,100 @@ namespace spot
     }
   }
 
+  static
+  acc_cond::mark_t merge_marks(acc_cond::mark_t colors,
+                               std::vector<acc_cond::mark_t> inclusions)
+  {
+    bool changed;
+    do
+    {
+      changed = false;
+      for (unsigned c : colors.sets())
+      {
+        if ((inclusions[c] & colors) != acc_cond::mark_t {})
+        {
+          auto new_colors = (colors - inclusions[c]);
+          if (new_colors != colors)
+            changed = true;
+          colors = new_colors;
+          break;
+        }
+      }
+    } while (changed);
+    return colors;
+  }
+
+  static
+  acc_cond::acc_code merge_colors(acc_cond::acc_code code,
+                                  std::vector<acc_cond::mark_t> inclusions)
+  {
+    if (code.empty())
+      return {};
+    int pos = code.size() - 1;
+    acc_cond::acc_code result;
+    do
+    {
+      switch (code[pos].sub.op)
+      {
+        case acc_cond::acc_op::And:
+        {
+          result = acc_cond::acc_code::t();
+          --pos;
+          while (pos > 0)
+          {
+            result = merge_colors(acc_cond::acc_code(&code[pos]), inclusions)
+                     & result;
+            pos -= (code[pos].sub.size + 1);
+          }
+          return result;
+        }
+        case acc_cond::acc_op::Or:
+        {
+          result = acc_cond::acc_code::f();
+          --pos;
+          while (pos > 0)
+          {
+            result = merge_colors(acc_cond::acc_code(&code[pos]), inclusions)
+                     | result;
+            pos -= (code[pos].sub.size + 1);
+          }
+          return result;
+        }
+        case acc_cond::acc_op::Fin:
+        {
+          auto res =  acc_cond::acc_code::fin(merge_marks(code[pos - 1].mark,
+                                                          inclusions));
+
+          return res;
+        }
+        case acc_cond::acc_op::Inf:
+        {
+          auto res =  acc_cond::acc_code::inf(merge_marks(code[pos - 1].mark,
+                                                          inclusions));
+          return res;
+        }
+        default:
+          SPOT_UNREACHABLE();
+      }
+    } while (pos > 0);
+    SPOT_UNREACHABLE();
+  }
+
+  // Create a vector of marks such that for every color c, result[c] contains
+  // all the colors that are on every transitions that also contain c
+  // (c is excluded).
+  static std::vector<acc_cond::mark_t> included_marks(twa_graph_ptr aut)
+  {
+    std::vector<acc_cond::mark_t> result(SPOT_MAX_ACCSETS,
+                                         acc_cond::mark_t::all());
+    for (unsigned i = 0; i < SPOT_MAX_ACCSETS; ++i)
+      result[i]^= acc_cond::mark_t {i};
+    for (auto& e: aut->edges())
+      for (auto c : e.acc.sets())
+        result[c] &= e.acc;
+    return result;
+  }
+
   twa_graph_ptr simplify_acceptance_here(twa_graph_ptr aut)
   {
     for (;;)
@@ -621,7 +715,10 @@ namespace spot
         merge_identical_marks_here(aut);
         if (aut->acc().is_generalized_buchi())
           break;
-        acc_cond::acc_code old = aut->get_acceptance();
+        auto inc = included_marks(aut);
+        auto new_code = merge_colors(aut->get_acceptance(), inc);
+        aut->set_acceptance(acc_cond(aut->num_sets(), new_code));
+        acc_cond::acc_code old = new_code;
         aut->set_acceptance(aut->acc().unit_propagation());
         simplify_complementary_marks_here(aut);
         fuse_marks_here(aut);

tests/core/remfin.test

@@ -311,48 +311,46 @@ 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 {1 3}
-[0] 1 {1 3}
-[!0] 2 {1 3}
+[t] 0 {0}
+[0] 1 {0}
+[!0] 2 {0}
 State: 1
-[1] 0 {1}
-[0&1] 1 {1}
-[!0&1] 2 {1 2}
+[1] 0
+[0&1] 1
+[!0&1] 2 {0}
 State: 2
 [!1] 0
 [0&!1] 1
-[!0&!1] 2
-[!0&!1] 3
-State: 3
-[!0&!1] 3 {0}
+[!0&!1] 2 {0}
 --END--
 HOA: v1
 States: 3
 Start: 0
 AP: 2 "a" "b"
-acc-name: generalized-Buchi 2
-Acceptance: 2 Inf(0)&Inf(1)
+acc-name: Buchi
+Acceptance: 1 Inf(0)
 properties: trans-labels explicit-labels trans-acc
 --BODY--
 State: 0
-[t] 0 {1}
-[0] 1 {1}
-[!0] 2 {0 1}
+[t] 0
+[0] 1
+[!0] 2 {0}
 State: 1
-[1] 0 {1}
-[0&1] 1 {0 1}
-[!0&1] 2 {0 1}
+[1] 0
+[0&1] 1 {0}
+[!0&1] 2 {0}
 State: 2
 [!1] 0
-[0&!1] 1 {0 1}
-[!0&!1] 2 {0 1}
+[0&!1] 1 {0}
+[!0&!1] 2 {0}
 --END--
 HOA: v1
 States: 1
@@ -842,25 +840,23 @@ HOA: v1
 States: 4
 Start: 0
 AP: 2 "b" "c"
-acc-name: generalized-Buchi 2
-Acceptance: 2 Inf(0)&Inf(1)
+acc-name: Buchi
+Acceptance: 1 Inf(0)
 properties: trans-labels explicit-labels trans-acc
 --BODY--
 State: 0
-[!0] 0
-[!0] 1
-[0] 0
-[0] 1
-[0&!1] 2
-[0&1] 3
+[t] 0
+[0&!1] 1
+[0&1] 2
+[!0] 3
 State: 1
-[!0] 1 {0 1}
+[!0 | !1] 1 {0}
+[0&1] 2
 State: 2
-[!0 | !1] 2 {0 1}
-[0&1] 3 {0}
+[!1] 1 {0}
+[1] 2
 State: 3
-[!1] 2 {0 1}
-[1] 3 {0}
+[!0] 3 {0}
 --END--
 HOA: v1
 States: 6
@@ -912,7 +908,7 @@ State: 2 {0}
 [!1] 2
 --END--
 HOA: v1
-States: 4
+States: 3
 Start: 0
 AP: 2 "a" "b"
 acc-name: Buchi
@@ -930,10 +926,7 @@ State: 1
 State: 2
 [!1] 0
 [0&!1] 1
-[!0&!1] 2
-[!0&!1] 3
-State: 3
-[!0&!1] 3 {0}
+[!0&!1] 2 {0}
 --END--
 HOA: v1
 States: 3

tests/python/remfin.py

@@ -92,4 +92,4 @@ State: 2
 """)
 b = spot.remove_fin(a)
 size = (b.num_states(), b.num_edges())
-assert size == (5, 15);
+assert size == (5, 17);

tests/python/simplacc.py

@@ -60,6 +60,11 @@ HOA: v1 States: 2 Start: 0 AP: 2 "p0" "p1" Acceptance: 5 Fin(0) &
 (((Fin(1)|Fin(2)|Fin(3))&Inf(4)|Fin(3))) properties: trans-labels
 explicit-labels trans-acc --BODY-- State: 0 [!0&!1] 0 {0 1 3} [0&1] 1
 {0 2} [0&!1] 0 {2} State: 1 [0&1] 0 {0 2} [0&1] 1 {1} [0&!1] 1 {4} --END--
+/* Issue #406 */
+HOA: v1 States: 2 Start: 0 AP: 2 "p0" "p1" Acceptance: 4
+(Fin(3) & (Inf(1) | Fin(0))) | (Inf(0)&Inf(2)&Inf(3)) properties: trans-labels
+explicit-labels trans-acc deterministic --BODY-- State: 0 [0&!1] 0 {2 3}
+[!0&!1] 1 {0 1} State: 1 [!0&!1] 0 {0 1} [0&1] 1 {1 2} --END--
 """))
 
 res = []
@@ -90,8 +95,10 @@ assert res == [
     '((Inf(1) & Fin(2)) | Fin(5)) & (Inf(0) | (Inf(1) & (Inf(3) | Fin(4))))',
     'Inf(0)',
     'Fin(0)',
-    'Fin(0)|Fin(1)|Fin(2)',
-    'Inf(0)&Inf(1)&Inf(2)',
-    '((Fin(0)|Fin(1)) & Inf(3)) | Fin(2)',
-    '((Inf(0)&Inf(1)) | Fin(3)) & Inf(2)',
+    'Fin(0)',
+    'Inf(0)',
+    '(Fin(0) & Inf(2)) | Fin(1)',
+    '(Inf(0) | Fin(2)) & Inf(1)',
+    '(Fin(2) & (Inf(1) | Fin(0))) | (Inf(0)&Inf(2))',
+    '(Inf(2) | (Fin(1) & Inf(0))) & (Fin(0)|Fin(2))',
     ]