spot/spot/twaalgos/product.cc
Alexandre Duret-Lutz 0f131f2eee product: Büchi|Büchi=Büchi, CoBüchi&CoBüchi=CoBüchi
Improve the construction of the above constructions, saving colors.

* spot/twaalgos/product.cc: Here.
* spot/twaalgos/product.hh, NEWS: Mention it.
* tests/core/prodchain.test, tests/core/prodor.test,
tests/python/_product_weak.ipynb: Adjust.
2022-09-06 18:05:52 +02:00

730 lines
28 KiB
C++

// -*- coding: utf-8 -*-
// Copyright (C) 2014-2020, 2022 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/>.
#include "config.h"
#include <spot/twaalgos/product.hh>
#include <spot/twa/twagraph.hh>
#include <spot/twaalgos/complete.hh>
#include <spot/twaalgos/sccinfo.hh>
#include <spot/twaalgos/isdet.hh>
#include <deque>
#include <unordered_map>
#include <spot/misc/hash.hh>
namespace spot
{
namespace
{
typedef std::pair<unsigned, unsigned> product_state;
struct product_state_hash
{
size_t
operator()(product_state s) const noexcept
{
return wang32_hash(s.first ^ wang32_hash(s.second));
}
};
template<typename T>
static
void product_main(const const_twa_graph_ptr& left,
const const_twa_graph_ptr& right,
unsigned left_state,
unsigned right_state,
twa_graph_ptr& res, T merge_acc,
const output_aborter* aborter)
{
std::unordered_map<product_state, unsigned, product_state_hash> s2n;
std::deque<std::pair<product_state, unsigned>> todo;
auto v = new product_states;
res->set_named_prop("product-states", v);
auto new_state =
[&](unsigned left_state, unsigned right_state) -> unsigned
{
product_state x(left_state, right_state);
auto p = s2n.emplace(x, 0);
if (p.second) // This is a new state
{
p.first->second = res->new_state();
todo.emplace_back(x, p.first->second);
assert(p.first->second == v->size());
v->emplace_back(x);
}
return p.first->second;
};
res->set_init_state(new_state(left_state, right_state));
if (res->acc().is_f())
// Do not bother doing any work if the resulting acceptance is
// false.
return;
while (!todo.empty())
{
if (aborter && aborter->too_large(res))
{
res = nullptr;
return;
}
auto top = todo.front();
todo.pop_front();
for (auto& l: left->out(top.first.first))
for (auto& r: right->out(top.first.second))
{
auto cond = l.cond & r.cond;
if (cond == bddfalse)
continue;
auto dst = new_state(l.dst, r.dst);
res->new_edge(top.second, dst, cond,
merge_acc(l.acc, r.acc));
// If right is deterministic, we can abort immediately!
}
}
}
enum acc_op { and_acc, or_acc, xor_acc, xnor_acc };
static
twa_graph_ptr product_aux(const const_twa_graph_ptr& left,
const const_twa_graph_ptr& right,
unsigned left_state,
unsigned right_state,
acc_op aop,
const output_aborter* aborter)
{
if (SPOT_UNLIKELY(!(left->is_existential() && right->is_existential())))
throw std::runtime_error
("product() does not support alternating automata");
if (SPOT_UNLIKELY(left->get_dict() != right->get_dict()))
throw std::runtime_error("product: left and right automata should "
"share their bdd_dict");
auto res = make_twa_graph(left->get_dict());
res->copy_ap_of(left);
res->copy_ap_of(right);
auto& lacc = left->acc();
auto& racc = right->acc();
bool leftweak = left->prop_weak().is_true();
bool rightweak = right->prop_weak().is_true();
// The conjunction of two co-Büchi automata is a co-Büchi automaton.
// The disjunction of two Büchi automata is a Büchi automaton.
//
// The code to handle this case is similar to the weak_weak case,
// except we do not set the weak property on the result.
if (!leftweak
&& !rightweak
&& ((aop == and_acc && lacc.is_co_buchi() && racc.is_co_buchi())
|| (aop == or_acc && lacc.is_buchi() && racc.is_buchi())))
goto and_cobuchi_or_buchi;
// We have optimization to the standard product in case one
// of the arguments is weak.
if (leftweak || rightweak)
{
// If both automata are weak, we can restrict the result to
// t, f, Büchi or co-Büchi. We use co-Büchi only when
// t and f cannot be used, and both acceptance conditions
// are in {t,f,co-Büchi}.
if ((leftweak && rightweak))
{
weak_weak:
res->prop_weak(true);
and_cobuchi_or_buchi:
acc_cond::mark_t accmark = {0};
acc_cond::mark_t rejmark = {};
if ((lacc.is_co_buchi() && (racc.is_co_buchi()
|| racc.num_sets() == 0))
|| (lacc.num_sets() == 0 && racc.is_co_buchi()))
{
res->set_co_buchi();
std::swap(accmark, rejmark);
}
else if ((aop == and_acc && lacc.is_t() && racc.is_t())
|| (aop == or_acc && (lacc.is_t() || racc.is_t()))
|| (aop == xnor_acc && ((lacc.is_t() && racc.is_t()) ||
(lacc.is_f() && racc.is_f())))
|| (aop == xor_acc && ((lacc.is_t() && racc.is_f()) ||
(lacc.is_f() && racc.is_t()))))
{
res->set_acceptance(0, acc_cond::acc_code::t());
accmark = {};
}
else if ((aop == and_acc && (lacc.is_f() || racc.is_f()))
|| (aop == or_acc && lacc.is_f() && racc.is_f())
|| (aop == xor_acc && ((lacc.is_t() && racc.is_t()) ||
(lacc.is_f() && racc.is_f())))
|| (aop == xnor_acc && ((lacc.is_t() && racc.is_f()) ||
(lacc.is_f() && racc.is_t()))))
{
res->set_acceptance(0, acc_cond::acc_code::f());
accmark = {};
}
else
{
res->set_buchi();
}
switch (aop)
{
case and_acc:
product_main(left, right, left_state, right_state, res,
[&] (acc_cond::mark_t ml, acc_cond::mark_t mr)
{
if (lacc.accepting(ml) && racc.accepting(mr))
return accmark;
else
return rejmark;
}, aborter);
break;
case or_acc:
product_main(left, right, left_state, right_state, res,
[&] (acc_cond::mark_t ml, acc_cond::mark_t mr)
{
if (lacc.accepting(ml) || racc.accepting(mr))
return accmark;
else
return rejmark;
}, aborter);
break;
case xor_acc:
product_main(left, right, left_state, right_state, res,
[&] (acc_cond::mark_t ml, acc_cond::mark_t mr)
{
if (lacc.accepting(ml) ^ racc.accepting(mr))
return accmark;
else
return rejmark;
}, aborter);
break;
case xnor_acc:
product_main(left, right, left_state, right_state, res,
[&] (acc_cond::mark_t ml, acc_cond::mark_t mr)
{
if (lacc.accepting(ml) == racc.accepting(mr))
return accmark;
else
return rejmark;
}, aborter);
break;
}
}
else if (!rightweak)
{
switch (aop)
{
case and_acc:
{
auto rightunsatmark = right->acc().unsat_mark();
if (!rightunsatmark.first)
{
// Left is weak. Right was not weak, but it is
// always accepting. We can therefore pretend
// that right is weak.
goto weak_weak;
}
res->copy_acceptance_of(right);
acc_cond::mark_t rejmark = rightunsatmark.second;
auto& lacc = left->acc();
product_main(left, right, left_state, right_state, res,
[&] (acc_cond::mark_t ml, acc_cond::mark_t mr)
{
if (lacc.accepting(ml))
return mr;
else
return rejmark;
}, aborter);
break;
}
case or_acc:
{
auto rightsatmark = right->acc().sat_mark();
if (!rightsatmark.first)
{
// Left is weak. Right was not weak, but it is
// always rejecting. We can therefore pretend
// that right is weak.
goto weak_weak;
}
res->copy_acceptance_of(right);
acc_cond::mark_t accmark = rightsatmark.second;
auto& lacc = left->acc();
product_main(left, right, left_state, right_state, res,
[&] (acc_cond::mark_t ml, acc_cond::mark_t mr)
{
if (!lacc.accepting(ml))
return mr;
else
return accmark;
}, aborter);
break;
}
case xor_acc:
case xnor_acc:
{
auto rightsatmark = right->acc().sat_mark();
auto rightunsatmark = right->acc().unsat_mark();
if (!rightunsatmark.first || !rightsatmark.first)
{
// Left is weak. Right was not weak, but it
// is either always rejecting or always
// accepting. We can therefore pretend that
// right is weak.
goto weak_weak;
}
goto generalcase;
break;
}
}
}
else // right weak
{
assert(!leftweak);
switch (aop)
{
case and_acc:
{
auto leftunsatmark = left->acc().unsat_mark();
if (!leftunsatmark.first)
{
// Right is weak. Left was not weak, but it is
// always accepting. We can therefore pretend
// that left is weak.
goto weak_weak;
}
res->copy_acceptance_of(left);
acc_cond::mark_t rejmark = leftunsatmark.second;
auto& racc = right->acc();
product_main(left, right, left_state, right_state, res,
[&] (acc_cond::mark_t ml, acc_cond::mark_t mr)
{
if (racc.accepting(mr))
return ml;
else
return rejmark;
}, aborter);
break;
}
case or_acc:
{
auto leftsatmark = left->acc().sat_mark();
if (!leftsatmark.first)
{
// Right is weak. Left was not weak, but it is
// always rejecting. We can therefore pretend
// that left is weak.
goto weak_weak;
}
res->copy_acceptance_of(left);
acc_cond::mark_t accmark = leftsatmark.second;
auto& racc = right->acc();
product_main(left, right, left_state, right_state, res,
[&] (acc_cond::mark_t ml, acc_cond::mark_t mr)
{
if (!racc.accepting(mr))
return ml;
else
return accmark;
}, aborter);
break;
}
case xor_acc:
case xnor_acc:
{
auto leftsatmark = left->acc().sat_mark();
auto leftunsatmark = left->acc().unsat_mark();
if (!leftunsatmark.first || !leftsatmark.first)
{
// Right is weak. Left was not weak, but it
// is either always rejecting or always
// accepting. We can therefore pretend that
// left is weak.
goto weak_weak;
}
goto generalcase;
break;
}
}
}
}
else // general case
{
generalcase:
auto left_num = left->num_sets();
auto& left_acc = left->get_acceptance();
auto right_acc = right->get_acceptance() << left_num;
switch (aop)
{
case and_acc:
right_acc &= left_acc;
break;
case or_acc:
right_acc |= left_acc;
break;
case xor_acc:
{
auto tmp = right_acc.complement() & left_acc;
right_acc &= left_acc.complement();
right_acc |= tmp;
break;
}
case xnor_acc:
{
auto tmp = right_acc.complement() & left_acc.complement();
right_acc &= left_acc;
tmp |= right_acc;
std::swap(tmp, right_acc);
break;
}
}
res->set_acceptance(left_num + right->num_sets(), right_acc);
product_main(left, right, left_state, right_state, res,
[&] (acc_cond::mark_t ml, acc_cond::mark_t mr)
{
return ml | (mr << left_num);
}, aborter);
}
if (!res) // aborted
return nullptr;
if (res->acc().is_f())
{
assert(res->num_edges() == 0);
res->prop_universal(true);
res->prop_complete(false);
res->prop_stutter_invariant(true);
res->prop_terminal(true);
res->prop_state_acc(true);
}
else
{
// The product of two non-deterministic automata could be
// deterministic. Likewise for non-complete automata.
if (left->prop_universal() && right->prop_universal())
res->prop_universal(true);
if (left->prop_complete() && right->prop_complete())
res->prop_complete(true);
if (left->prop_stutter_invariant() && right->prop_stutter_invariant())
res->prop_stutter_invariant(true);
if (left->prop_inherently_weak() && right->prop_inherently_weak())
res->prop_inherently_weak(true);
if (left->prop_weak() && right->prop_weak())
res->prop_weak(true);
if (left->prop_terminal() && right->prop_terminal())
res->prop_terminal(true);
res->prop_state_acc(left->prop_state_acc()
&& right->prop_state_acc());
}
return res;
}
}
twa_graph_ptr product(const const_twa_graph_ptr& left,
const const_twa_graph_ptr& right,
unsigned left_state,
unsigned right_state,
const output_aborter* aborter)
{
return product_aux(left, right, left_state, right_state, and_acc, aborter);
}
twa_graph_ptr product(const const_twa_graph_ptr& left,
const const_twa_graph_ptr& right,
const output_aborter* aborter)
{
return product(left, right,
left->get_init_state_number(),
right->get_init_state_number(), aborter);
}
twa_graph_ptr product_or(const const_twa_graph_ptr& left,
const const_twa_graph_ptr& right,
unsigned left_state,
unsigned right_state)
{
return product_aux(complete(left), complete(right),
left_state, right_state, or_acc, nullptr);
}
twa_graph_ptr product_or(const const_twa_graph_ptr& left,
const const_twa_graph_ptr& right)
{
return product_or(left, right,
left->get_init_state_number(),
right->get_init_state_number());
}
twa_graph_ptr product_xor(const const_twa_graph_ptr& left,
const const_twa_graph_ptr& right)
{
if (SPOT_UNLIKELY(!is_deterministic(left) || !is_deterministic(right)))
throw std::runtime_error
("product_xor() only works with deterministic automata");
return product_aux(complete(left), complete(right),
left->get_init_state_number(),
right->get_init_state_number(),
xor_acc, nullptr);
}
twa_graph_ptr product_xnor(const const_twa_graph_ptr& left,
const const_twa_graph_ptr& right)
{
if (SPOT_UNLIKELY(!is_deterministic(left) || !is_deterministic(right)))
throw std::runtime_error
("product_xnor() only works with deterministic automata");
return product_aux(complete(left), complete(right),
left->get_init_state_number(),
right->get_init_state_number(),
xnor_acc, nullptr);
}
namespace
{
template<typename T>
static void
product_susp_aux(const const_twa_graph_ptr& left,
const const_twa_graph_ptr& right,
twa_graph_ptr res, bool and_acc,
bool sync_all, acc_cond::mark_t rejmark, T merge_acc)
{
std::unordered_map<product_state, unsigned, product_state_hash> s2n;
std::deque<std::pair<product_state, unsigned>> todo;
scc_info si(left,
and_acc ? scc_info_options::TRACK_STATES_IF_FIN_USED
: (scc_info_options::TRACK_STATES_IF_FIN_USED
| scc_info_options::TRACK_SUCCS));
si.determine_unknown_acceptance();
auto new_state =
[&](unsigned left_state, unsigned right_state) -> unsigned
{
product_state x(left_state, right_state);
auto p = s2n.emplace(x, 0);
if (p.second) // This is a new state
{
p.first->second = res->new_state();
todo.emplace_back(x, p.first->second);
}
return p.first->second;
};
unsigned right_init = right->get_init_state_number();
unsigned left_init = left->get_init_state_number();
unsigned res_init;
auto target_scc = [&](unsigned scc) -> bool
{
return (!si.is_trivial(scc)
&& (sync_all || si.is_accepting_scc(scc) == and_acc));
};
if (target_scc(si.scc_of(left_init)))
res_init = new_state(left_init, right_init);
else
res_init = new_state(left_init, -1U);
res->set_init_state(res_init);
bool sbacc = res->prop_state_acc().is_true();
while (!todo.empty())
{
auto top = todo.front();
todo.pop_front();
for (auto& l: left->out(top.first.first))
if (!target_scc(si.scc_of(l.dst)))
{
acc_cond::mark_t right_acc =
(sbacc && top.first.second != -1U)
// This edge leaves a target SCC, but we build a
// state-based automaton, so make sure we still use
// the same acceptance marks as in the SCC we leave.
? right->state_acc_sets(top.first.second)
: rejmark;
res->new_edge(top.second, new_state(l.dst, -1U), l.cond,
merge_acc(l.acc, right_acc));
}
else
{
unsigned right_state = top.first.second;
if (top.first.second == -1U)
right_state = right_init;
for (auto& r: right->out(right_state))
{
auto cond = l.cond & r.cond;
if (cond == bddfalse)
continue;
auto dst = new_state(l.dst, r.dst);
// For state-based automata, we cannot use the
// right-mark when entering a target SCC, because
// another sibling transition might be going to a
// non-target SCC without this mark.
acc_cond::mark_t right_acc =
(sbacc && top.first.second == -1U) ? rejmark : r.acc;
res->new_edge(top.second, dst, cond,
merge_acc(l.acc, right_acc));
}
}
}
}
static twa_graph_ptr
product_susp_main(const const_twa_graph_ptr& left,
const const_twa_graph_ptr& right,
bool and_acc = true)
{
if (SPOT_UNLIKELY(!(left->is_existential() && right->is_existential())))
throw std::runtime_error
("product_susp() does not support alternating automata");
if (SPOT_UNLIKELY(left->get_dict() != right->get_dict()))
throw std::runtime_error("product_susp(): left and right automata "
"should share their bdd_dict");
auto false_or_left = [&] (bool ff)
{
if (ff)
{
auto res = make_twa_graph(left->get_dict());
res->new_state();
res->prop_terminal(true);
res->prop_stutter_invariant(true);
res->prop_universal(true);
res->prop_complete(false);
return res;
}
return make_twa_graph(left, twa::prop_set::all());
};
// We assume RIGHT is suspendable, but we want to deal with some
// trivial true/false cases so we can later assume right has
// more than one acceptance set.
// Note: suspendable with "t" acceptance = universal language.
if (SPOT_UNLIKELY(right->num_sets() == 0))
{
if (and_acc)
return false_or_left(right->is_empty());
else if (right->is_empty()) // left OR false = left
return make_twa_graph(left, twa::prop_set::all());
else // left OR true = true
return make_twa_graph(right, twa::prop_set::all());
}
auto res = make_twa_graph(left->get_dict());
res->copy_ap_of(left);
res->copy_ap_of(right);
bool leftweak = left->prop_weak().is_true();
res->prop_state_acc(left->prop_state_acc() && right->prop_state_acc());
auto rightunsatmark = right->acc().unsat_mark();
if (SPOT_UNLIKELY(!rightunsatmark.first))
return false_or_left(and_acc);
acc_cond::mark_t rejmark = rightunsatmark.second;
if (leftweak)
{
res->copy_acceptance_of(right);
if (and_acc)
{
product_susp_aux(left, right, res, true, false, rejmark,
[&] (acc_cond::mark_t,
acc_cond::mark_t mr)
{
return mr;
});
}
else
{
auto rightsatmark = right->acc().sat_mark();
if (!rightsatmark.first)
// Right is always rejecting, no point in making a product_or
return make_twa_graph(left, twa::prop_set::all());
acc_cond::mark_t accmark = rightsatmark.second;
auto& lacc = left->acc();
product_susp_aux(left, right, res, false, false, rejmark,
[&] (acc_cond::mark_t ml,
acc_cond::mark_t mr)
{
if (!lacc.accepting(ml))
return mr;
else
return accmark;
});
}
}
else // general case
{
auto left_num = left->num_sets();
auto right_acc = right->get_acceptance() << left_num;
if (and_acc)
right_acc &= left->get_acceptance();
else
right_acc |= left->get_acceptance();
res->set_acceptance(left_num + right->num_sets(), right_acc);
product_susp_aux(left, right, res, and_acc, !and_acc, rejmark,
[&] (acc_cond::mark_t ml,
acc_cond::mark_t mr)
{
return ml | (mr << left_num);
});
}
// The product of two non-deterministic automata could be
// deterministic. Likewise for non-complete automata.
if (left->prop_universal() && right->prop_universal())
res->prop_universal(true);
if (left->prop_complete() && right->prop_complete())
res->prop_complete(true);
if (left->prop_stutter_invariant() && right->prop_stutter_invariant())
res->prop_stutter_invariant(true);
if (left->prop_inherently_weak() && right->prop_inherently_weak())
res->prop_inherently_weak(true);
if (left->prop_weak() && right->prop_weak())
res->prop_weak(true);
if (left->prop_terminal() && right->prop_terminal())
res->prop_terminal(true);
return res;
}
}
twa_graph_ptr product_susp(const const_twa_graph_ptr& left,
const const_twa_graph_ptr& right)
{
return product_susp_main(left, right);
}
twa_graph_ptr product_or_susp(const const_twa_graph_ptr& left,
const const_twa_graph_ptr& right)
{
return product_susp_main(complete(left), right, false);
}
}