acd: remove redundant nodes

Reported by Florian Renkin.

* spot/twaalgos/zlktree.cc (acd::_build): Use a sorted list to remove
redundant children, has done in zielonka_tree.
* tests/python/zlktree.ipynb: Add Florian's test case.
* tests/python/toparity.py: Adjust, and revert some tests
uncommented by mistake in a previous patch.

spot/twaalgos/zlktree.cc

@@ -20,9 +20,11 @@
 #include "config.h"
 #include <iostream>
 #include <deque>
+#include <memory>
 #include <spot/twaalgos/zlktree.hh>
 #include <spot/twaalgos/genem.hh>
 #include <spot/misc/escape.hh>
+#include <spot/misc/bitvect.hh>
 
 namespace spot
 {
@@ -405,6 +407,13 @@ namespace spot
           }
       }
 
+    struct size_model
+    {
+      unsigned size;
+      std::unique_ptr<bitvect> trans;
+    };
+    std::vector<size_model> out;
+
     // This loop is a BFS over the increasing set of nodes.
     for (unsigned node = 0; node < nodes_.size(); ++node)
     {
@@ -412,26 +421,60 @@ namespace spot
       unsigned lvl = nodes_[node].level;
       bool accepting_node = (lvl & 1) != trees_[scc].is_even;
 
+      out.clear();
       auto callback = [&](scc_info si, unsigned siscc)
       {
-        unsigned vnum = trees_[scc].num_nodes++;
-        allocate_vectors_maybe(vnum);
-        nodes_.emplace_back(edge_vector(vnum), state_vector(vnum));
-        auto& n = nodes_.back();
-        n.parent = node;
-        n.level = lvl + 1;
-        n.scc = scc;
+        bitvect* bv = make_bitvect(nedges);
+        unsigned sz = 0;
         for (auto& e: si.inner_edges_of(siscc))
           {
-            n.edges[aut->edge_number(e)] = true;
-            n.states[e.src] = true;
+            bv->set(aut->edge_number(e));
+            ++sz;
           }
+        auto iter = out.begin();
+        while (iter != out.end())
+          {
+            if (iter->size < sz)
+              // We have checked all larger models.
+              break;
+            if (bv->is_subset_of(*iter->trans))
+              // ignore smaller models
+              {
+                delete bv;
+                return;
+              }
+            ++iter;
+          }
+        // insert the model
+        iter = out.insert(iter, {sz, std::unique_ptr<bitvect>(bv)});
+        ++iter;
+        // erase all models it contains
+        out.erase(std::remove_if(iter, out.end(),
+                                 [&](auto& mod) {
+                                   return mod.trans->is_subset_of(*bv);
+                                 }), out.end());
       };
-
-      unsigned before_size = nodes_.size();
       maximal_accepting_loops_for_scc(*si_, scc,
                                       accepting_node ? negacc : posacc,
                                       nodes_[node].edges, callback);
+
+      unsigned before_size = nodes_.size();
+      for (const auto& [sz, bv]: out)
+        {
+          unsigned vnum = trees_[scc].num_nodes++;
+          allocate_vectors_maybe(vnum);
+          nodes_.emplace_back(edge_vector(vnum), state_vector(vnum));
+          auto& n = nodes_.back();
+          n.parent = node;
+          n.level = lvl + 1;
+          n.scc = scc;
+          for (unsigned e = 1; e < nedges; ++e)
+            if (bv->get(e))
+              {
+                n.edges[e] = true;
+                n.states[aut->edge_storage(e).src] = true;
+              }
+        }
       unsigned after_size = nodes_.size();
       unsigned children = after_size - before_size;
 

tests/python/toparity.py

@@ -116,7 +116,7 @@ def test(aut, expected_num_states=[], full=True):
             spot.reduce_parity_here(p1)
         assert spot.are_equivalent(aut, p1)
         if expected_num is not None:
-            print(p1.num_states(), expected_num)
+            # print(p1.num_states(), expected_num)
             assert p1.num_states() == expected_num
         if full and opt is not None:
             # Make sure passing opt is the same as setting
@@ -240,11 +240,11 @@ State: 1
 [!0&!1] 0 {1 2}
 --END--"""), [9, 3, 2, 3, 3, 3, 2, 2])
 
-#for i,f in enumerate(spot.randltl(10, 400)):
-#    test(spot.translate(f, "det", "G"), full=(i<100))
-#
-#for f in spot.randltl(5, 2500):
-#    test(spot.translate(f), full=False)
+for i,f in enumerate(spot.randltl(10, 200)):
+    test(spot.translate(f, "det", "G"), full=(i<50))
+
+for f in spot.randltl(5, 500):
+    test(spot.translate(f), full=False)
 
 
 test(spot.automaton("""
@@ -278,7 +278,7 @@ State: 3
 [!0&1] 2 {1 4}
 [0&1] 3 {0}
 --END--
-"""), [80, 47, 104, 104, 102, 29, 6, 6])
+"""), [80, 47, 104, 104, 102, 29, 6, 5])
 
 test(spot.automaton("""
 HOA: v1