autfilt add support for --partial-degeneralize

* bin/autfilt.cc: Add a --partial-degeneralize option.
* NEWS: Mention it.
* spot/twaalgos/degen.cc: Do not restrict partial_degeneralize() to
deterministic automata.
* spot/twaalgos/degen.hh: Adjust documentation.
* tests/core/pdegen.test: New test case.
* tests/Makefile.am: Add it.
* tests/python/pdegen.py: Adjust.

NEWS

@@ -17,6 +17,10 @@ New in spot 2.8.5.dev (not yet released)
   - When running translators ltlcross will now display {names} when
     supplied.
 
+  - autfilt learned the --partial-degeneralize option, to remove
+    conjunctions of Inf, or disjunction of Fin that appears in
+    arbitrary conditions.
+
   Library:
 
   - Historically, Spot only supports LTL with infinite semantics
@@ -58,9 +62,8 @@ New in spot 2.8.5.dev (not yet released)
        parity_min_even(n) = parity_min(false, n)
 
   - partial_degeneralize() is a new function performing partial
-    degeneralization to get rid of conjunctions of Inf terms in
-    acceptance conditions.  This also works with disjunctions of
-    Fin terms in deterministic automata.
+    degeneralization to get rid of conjunctions of Inf terms, or
+    disjunctions of Fin terms in acceptance conditions.
 
   - simplify_acceptance_here() and simplify_acceptance() learned to
     simplify subformulas like Fin(i)&Fin(j) or Inf(i)|Inf(j), or some

bin/autfilt.cc

@@ -1,5 +1,5 @@
 // -*- coding: utf-8 -*-
-// Copyright (C) 2013-2019 Laboratoire de Recherche et Développement
+// Copyright (C) 2013-2020 Laboratoire de Recherche et Développement
 // de l'Epita (LRDE).
 //
 // This file is part of Spot, a model checking library.
@@ -133,6 +133,7 @@ enum {
   OPT_MASK_ACC,
   OPT_MERGE,
   OPT_NONDET_STATES,
+  OPT_PARTIAL_DEGEN,
   OPT_PRODUCT_AND,
   OPT_PRODUCT_OR,
   OPT_RANDOMIZE,
@@ -363,6 +364,10 @@ static const argp_option options[] =
     { "sum-and", OPT_SUM_AND, "FILENAME", 0,
       "build the sum with the automaton in FILENAME "
       "to intersect languages", 0 },
+    { "partial-degeneralize", OPT_PARTIAL_DEGEN, "NUM1,NUM2,...",
+      OPTION_ARG_OPTIONAL, "Degeneralize automata according to sets "
+      "NUM1,NUM2,... If no sets are given, partial degeneralization "
+      "is performed for all conjunctions of Inf and disjunctions of Fin.", 0 },
     { "separate-sets", OPT_SEP_SETS, nullptr, 0,
       "if both Inf(x) and Fin(x) appear in the acceptance condition, replace "
       "Fin(x) by a new Fin(y) and adjust the automaton", 0 },
@@ -619,6 +624,8 @@ static bool opt_complement = false;
 static bool opt_complement_acc = false;
 static char* opt_decompose_scc = nullptr;
 static bool opt_dualize = false;
+static bool opt_partial_degen_set = false;
+static spot::acc_cond::mark_t opt_partial_degen = {};
 static spot::acc_cond::mark_t opt_mask_acc = {};
 static std::vector<bool> opt_keep_states = {};
 static unsigned int opt_keep_states_initial = 0;
@@ -1005,6 +1012,23 @@ parse_opt(int key, char* arg, struct argp_state*)
       opt_nondet_states = parse_range(arg, 0, std::numeric_limits<int>::max());
       opt_nondet_states_set = true;
       break;
+    case OPT_PARTIAL_DEGEN:
+      {
+        opt_partial_degen_set = true;
+        if (arg)
+          for (auto res : to_longs(arg))
+            {
+              if (res < 0)
+                error(2, 0, "acceptance sets should be non-negative:"
+                      " --partial-degeneralize=%ld", res);
+              if (static_cast<unsigned long>(res) >=
+                  spot::acc_cond::mark_t::max_accsets())
+                error(2, 0, "this implementation does not support that many"
+                      " acceptance sets: --partial-degeneralize=%ld", res);
+              opt_partial_degen.set(res);
+            }
+        break;
+      }
     case OPT_PRODUCT_AND:
       {
         auto a = read_automaton(arg, opt->dict);
@@ -1478,6 +1502,19 @@ namespace
       else if (opt_rem_unreach)
         aut->purge_unreachable_states();
 
+      if (opt_partial_degen_set)
+        {
+          if (opt_partial_degen)
+            {
+              auto sets = opt_partial_degen & aut->acc().all_sets();
+              aut = spot::partial_degeneralize(aut, sets);
+            }
+          else
+            {
+              aut = spot::partial_degeneralize(aut);
+            }
+        }
+
       if (opt->product_and)
         aut = ::product(std::move(aut), opt->product_and);
       if (opt->product_or)

spot/twaalgos/degen.cc

@@ -750,8 +750,7 @@ namespace spot
   namespace
   {
     static acc_cond::mark_t
-    to_strip(const acc_cond::acc_code& code, acc_cond::mark_t todegen,
-             bool also_fin)
+    to_strip(const acc_cond::acc_code& code, acc_cond::mark_t todegen)
     {
       if (code.empty())
         return todegen;
@@ -768,14 +767,6 @@ namespace spot
               break;
             case acc_cond::acc_op::Fin:
             case acc_cond::acc_op::FinNeg:
-              if (!also_fin)
-                {
-                  pos -= 2;
-                  tostrip -= code[pos].mark;
-                  break;
-                }
-              // Handle Fin and Inf in the same way
-              SPOT_FALLTHROUGH;
             case acc_cond::acc_op::Inf:
             case acc_cond::acc_op::InfNeg:
               {
@@ -796,8 +787,7 @@ namespace spot
     update_acc_for_partial_degen(acc_cond::acc_code& code,
                                  acc_cond::mark_t todegen,
                                  acc_cond::mark_t tostrip,
-                                 acc_cond::mark_t accmark,
-                                 bool also_fin)
+                                 acc_cond::mark_t accmark)
     {
       if (!todegen || code.empty())
         {
@@ -817,14 +807,6 @@ namespace spot
               break;
             case acc_cond::acc_op::Fin:
             case acc_cond::acc_op::FinNeg:
-              if (!also_fin)
-                {
-                  pos -= 2;
-                  code[pos].mark = code[pos].mark.strip(tostrip);
-                  break;
-                }
-              // Handle Fin and Inf in the same way
-              SPOT_FALLTHROUGH;
             case acc_cond::acc_op::Inf:
             case acc_cond::acc_op::InfNeg:
               {
@@ -869,9 +851,6 @@ namespace spot
     if (code.empty())
       return {};
 
-    if (allow_fin)
-      allow_fin = is_deterministic(aut);
-
     acc_cond::mark_t res = {};
     unsigned res_sz = -1U;
     auto update = [&](const acc_cond::mark_t& m)
@@ -926,16 +905,11 @@ namespace spot
     res->copy_ap_of(a);
     acc_cond::acc_code acc = a->get_acceptance();
 
-    // We can also degeneralize disjunctions of Fin if the input is
-    // deterministic.
-    bool also_fin = a->acc().uses_fin_acceptance() && is_deterministic(a);
-
-    acc_cond::mark_t tostrip = to_strip(acc, todegen, also_fin);
+    acc_cond::mark_t tostrip = to_strip(acc, todegen);
     acc_cond::mark_t keep = a->acc().all_sets() - tostrip;
     acc_cond::mark_t degenmark = {keep.count()};
 
-    if (!update_acc_for_partial_degen(acc, todegen, tostrip, degenmark,
-                                      also_fin))
+    if (!update_acc_for_partial_degen(acc, todegen, tostrip, degenmark))
       report_invalid_partial_degen_arg(todegen, acc);
     res->set_acceptance(acc);
 

spot/twaalgos/degen.hh

@@ -107,13 +107,12 @@ namespace spot
   ///
   /// Cases where the sets listed in \a todegen also occur outside
   /// of the Inf-conjunction are also supported.  Subformulas that
-  /// are disjunctions of Fin(.) terms (e.g., Fin(1)|Fin(2)) can
-  /// also be degeneralized if the input automaton is deterministic.
+  /// are disjunctions of Fin(.) terms (e.g., Fin(1)|Fin(2)) will
+  /// be degeneralized as well.
   ///
   /// If this functions is called with a value of \a todegen that does
-  /// not match a conjunction of Inf(.), or in a deterministic
-  /// automaton a disjunction of Fin(.), an std::runtime_error
-  /// exception is thrown.
+  /// not match a conjunction of Inf(.), or a disjunction of Fin(.),
+  /// an std::runtime_error exception is thrown.
   ///
   /// The version of the function that has no \a todegen argument will
   /// perform all possible partial degeneralizations, and may return
@@ -132,10 +131,9 @@ namespace spot
 
   /// \brief Is the automaton partially degeneralizable?
   ///
-  /// Return a mark `M={m₁, m₂, ..., mₙ}` such that either (1)
-  /// `Inf(m₁)&Inf(m₂)&...&Inf(mₙ)` appears in the acceptance
-  /// condition of \a aut, or (2) \a aut is deterministic and
-  /// `Inf(m₁)|Inf(m₂)|...|Fin(mₙ)` appear in its conditions.
+  /// Return a mark `M={m₁, m₂, ..., mₙ}` such that either
+  /// `Inf(m₁)&Inf(m₂)&...&Inf(mₙ)` or `Fin(m₁)|Fin(m₂)|...|Fin(mₙ)`
+  /// appears in the acceptance condition of \a aut.
   ///
   /// If multiple such marks exist the smallest such mark is returned.
   /// (This is important in case of overlapping options.  E.g., in the

tests/Makefile.am

@@ -285,6 +285,7 @@ TESTS_twa = \
   core/ltl2dstar4.test \
   core/ltl2ta.test \
   core/ltl2ta2.test \
+  core/pdegen.test \
   core/randaut.test \
   core/randtgba.test \
   core/isomorph.test \

tests/core/pdegen.test

@@ -0,0 +1,32 @@
+#!/bin/sh
+# -*- coding: utf-8 -*-
+# Copyright (C) 2020 Laboratoire de Recherche et
+# Développement de l'Epita (LRDE).
+#
+# This file is part of Spot, a model checking library.
+#
+# Spot is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# Spot is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+# or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
+# License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+
+. ./defs
+
+set -e
+
+randaut -n10 -e.3 -Q7 -A 'generalized-co-Buchi 2..5' 2 |
+  autcross --verbose --language-preserved \
+      'autfilt --partial-degen' \
+      'autfilt --partial-degen=1,2,3'
+
+randaut -n10 -e.3 -Q7 -A 'random 2..5' 2 |
+  autcross --verbose --language-preserved 'autfilt --partial-degen'

tests/python/pdegen.py

@@ -144,10 +144,14 @@ State: 3 "2#0"
 
 assert spot.is_partially_degeneralizable(de) == []
 
+df = spot.partial_degeneralize(f, [0, 1])
+df.equivalent_to(f)
+assert str(df.acc()) == '(1, Fin(0))'
+
 try:
-    df = spot.partial_degeneralize(f, [0, 1])
+    df = spot.partial_degeneralize(f, [0, 1, 2])
 except RuntimeError as e:
-    assert 'partial_degeneralize(): {0,1} does not' in str(e)
+    assert 'partial_degeneralize(): {0,1,2} does not' in str(e)
 else:
     raise RuntimeError("missing exception")