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introduce realizability_simplifier to share more of ltlsynt's code

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* spot/tl/apcollect.hh,
spot/tl/apcollect.cc (realizability_simplifier): New class, built from
code existing in ltlsynt, so that other tools may use this too.
* bin/ltlsynt.cc: Use realizability_simplifier.
* spot/twaalgos/aiger.cc, spot/twaalgos/aiger.hh: Adjust to use
realizability_simplifier instead of relabeling_map.
* NEWS: Mention the new class.
This commit is contained in:
Alexandre Duret-Lutz 2023-10-09 17:53:12 +02:00
parent 9e40a32fd1
commit f2d034130a
6 changed files with 386 additions and 330 deletions
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279
bin/ltlsynt.cc
View file

@ -286,47 +286,15 @@ namespace
static void
dispatch_print_hoa(spot::twa_graph_ptr& game,
const std::vector<std::string>* input_aps = nullptr,
const spot::relabeling_map* rm = nullptr)
const spot::realizability_simplifier* rs = nullptr)
{
// Add any AP we removed. This is a game, so player moves are
// separated. Consequently at this point we cannot deal with
// removed signals such as "o1 <-> i2": if the game has to be
// printed, we can only optimize for signals such as o1 <-> o2.
if (rm && !rm->empty())
{
assert(input_aps);
auto& sp = spot::get_state_players(game);
if (rs)
rs->patch_game(game);
bdd add = bddtrue;
for (auto [k, v]: *rm)
{
int i = game->register_ap(k);
// skip inputs
if (std::find(input_aps->begin(), input_aps->end(),
k.ap_name()) != input_aps->end())
continue;
if (v.is_tt())
add &= bdd_ithvar(i);
else if (v.is_ff())
add &= bdd_nithvar(i);
else
{
bdd bv;
if (v.is(spot::op::ap))
bv = bdd_ithvar(game->register_ap(v.ap_name()));
else // Not Ap
bv = bdd_nithvar(game->register_ap(v[0].ap_name()));
add &= bdd_biimp(bdd_ithvar(i), bv);
}
}
for (auto& e: game->edges())
if (sp[e.src])
e.cond &= add;
set_synthesis_outputs(game,
get_synthesis_outputs(game)
& bdd_support(add));
}
if (opt_dot)
spot::print_dot(std::cout, game, opt_print_hoa_args);
else if (opt_print_pg)
@ -429,168 +397,26 @@ namespace
gi->bv->total_time = sw.stop();
};
// Check if some output propositions are always in positive form,
// or always in negative form.
// In syntcomp, this occurs more frequently for input variables than
// output variable. See issue #529 for some examples.
spot::relabeling_map rm;
bool first_dap = true;
auto display_ap = [&rm, &first_dap](spot::formula p)
{
if (SPOT_LIKELY(!gi->verbose_stream))
return;
if (first_dap)
{
*gi->verbose_stream
<< "the following signals can be temporarily removed:\n";
first_dap = false;
}
*gi->verbose_stream << " " << p << " := " << rm[p] <<'\n';
};
spot::formula oldf;
// Attempt to remove superfluous atomic propositions
spot::realizability_simplifier* rs = nullptr;
if (opt_polarity || opt_gequiv)
{
robin_hood::unordered_set<spot::formula> ap_inputs;
for (const std::string& ap: input_aps)
ap_inputs.insert(spot::formula::ap(ap));
do
unsigned opt = 0;
if (opt_polarity)
opt |= spot::realizability_simplifier::polarity;
if (opt_gequiv)
{
bool rm_has_new_terms = false;
oldf = f;
if (opt_polarity)
{
std::set<spot::formula> lits = spot::collect_literals(f);
for (const std::string& ap: output_aps)
{
spot::formula pos = spot::formula::ap(ap);
spot::formula neg = spot::formula::Not(pos);
bool has_pos = lits.find(pos) != lits.end();
bool has_neg = lits.find(neg) != lits.end();
if (has_pos ^ has_neg)
{
rm[pos] =
has_pos ? spot::formula::tt() : spot::formula::ff();
rm_has_new_terms = true;
display_ap(pos);
}
}
for (const std::string& ap: input_aps)
{
spot::formula pos = spot::formula::ap(ap);
spot::formula neg = spot::formula::Not(pos);
bool has_pos = lits.find(pos) != lits.end();
bool has_neg = lits.find(neg) != lits.end();
if (has_pos ^ has_neg)
{
rm[pos] =
has_neg ? spot::formula::tt() : spot::formula::ff();
rm_has_new_terms = true;
display_ap(pos);
}
}
if (rm_has_new_terms)
{
f = spot::relabel_apply(f, &rm);
if (gi->verbose_stream)
*gi->verbose_stream << "new formula: " << f << '\n';
rm_has_new_terms = false;
}
}
if (opt_gequiv)
{
// check for equivalent terms
spot::formula_ptr_less_than_bool_first cmp;
for (std::vector<spot::formula>& equiv:
spot::collect_equivalent_literals(f))
{
// For each set of equivalent literals, we want to
// pick a representative. That representative
// should be an input if one of the literal is an
// input. (If we have two inputs or more, the
// formula is not realizable.)
spot::formula repr = nullptr;
bool repr_is_input = false;
spot::formula input_seen = nullptr;
for (spot::formula lit: equiv)
{
spot::formula ap = lit;
if (ap.is(spot::op::Not))
ap = ap[0];
if (ap_inputs.find(ap) != ap_inputs.end())
{
if (input_seen)
{
// ouch! we have two equivalent inputs.
// This means the formula is simply
// unrealizable. Make it false for the
// rest of the algorithm.
f = spot::formula::ff();
goto done;
}
input_seen = lit;
// Normally, we want the input to be the
// representative. However as a special
// case, we ignore the input literal from
// the set if we are asked to print a
// game. Fixing the game to add a i<->o
// equivalence would require more code
// than I care to write.
//
// So if the set was {i,o1,o2}, instead
// of the desirable
// o1 := i
// o2 := i
// we only do
// o2 := o1
// when printing games.
if (!want_game())
{
repr_is_input = true;
repr = lit;
}
}
else if (!repr_is_input && (!repr || cmp(ap, repr)))
repr = lit;
}
// now map equivalent each atomic proposition to the
// representative
spot::formula not_repr = spot::formula::Not(repr);
for (spot::formula lit: equiv)
{
// input or representative are not removed
// (we have repr != input_seen either when input_seen
// is nullptr, or if want_game is true)
if (lit == repr || lit == input_seen)
continue;
if (lit.is(spot::op::Not))
{
spot::formula ap = lit[0];
rm[ap] = not_repr;
display_ap(ap);
}
else
{
rm[lit] = repr;
display_ap(lit);
}
rm_has_new_terms = true;
}
}
if (rm_has_new_terms)
{
f = spot::relabel_apply(f, &rm);
if (gi->verbose_stream)
*gi->verbose_stream << "new formula: " << f << '\n';
rm_has_new_terms = false;
}
}
if (want_game())
opt |= spot::realizability_simplifier::global_equiv_output_only;
else
opt |= spot::realizability_simplifier::global_equiv;
}
while (oldf != f);
done:
/* can't have a label followed by closing brace */;
rs =
new spot::realizability_simplifier(original_f,
input_aps,
opt,
gi ? gi->verbose_stream : nullptr);
f = rs->simplified_formula();
}
std::vector<spot::formula> sub_form;
@ -617,11 +443,18 @@ namespace
{
sub_form = { f };
sub_outs.resize(1);
for (const std::string& apstr: output_aps)
if (rs)
{
spot::formula ap = spot::formula::ap(apstr);
if (rm.find(ap) == rm.end())
sub_outs[0].insert(ap);
robin_hood::unordered_set<spot::formula> removed_outputs;
for (auto [from, from_is_input, to] : rs->get_mapping())
if (!from_is_input)
removed_outputs.insert(from);
for (const std::string& apstr: output_aps)
{
spot::formula ap = spot::formula::ap(apstr);
if (removed_outputs.find(ap) == removed_outputs.end())
sub_outs[0].insert(ap);
}
}
}
std::vector<std::vector<std::string>> sub_outs_str;
@ -683,7 +516,7 @@ namespace
}
if (want_game())
{
dispatch_print_hoa(arena, &input_aps, &rm);
dispatch_print_hoa(arena, rs);
continue;
}
if (!spot::solve_game(arena, *gi))
@ -772,7 +605,7 @@ namespace
sw2.start();
saig = spot::mealy_machines_to_aig(mealy_machines, opt_print_aiger,
input_aps,
sub_outs_str, &rm);
sub_outs_str, rs);
if (gi->bv)
{
gi->bv->aig_time = sw2.stop();
@ -804,52 +637,8 @@ namespace
for (size_t i = 1; i < mealy_machines.size(); ++i)
tot_strat = spot::mealy_product(tot_strat,
mealy_machines[i].mealy_like);
if (!rm.empty()) // Add any AP we removed
{
bdd add = bddtrue;
bdd additional_outputs = bddtrue;
for (auto [k, v]: rm)
{
int i = tot_strat->register_ap(k);
// skip inputs (they are don't care)
if (std::find(input_aps.begin(), input_aps.end(), k.ap_name())
!= input_aps.end())
continue;
if (v.is_tt())
{
bdd bv = bdd_ithvar(i);
additional_outputs &= bv;
add &= bv;
}
else if (v.is_ff())
{
additional_outputs &= bdd_ithvar(i);
add &= bdd_nithvar(i);
}
else
{
bdd left = bdd_ithvar(i); // this is necessarily an output
additional_outputs &= left;
bool pos = v.is(spot::op::ap);
const std::string apname =
pos ? v.ap_name() : v[0].ap_name();
bdd right = bdd_ithvar(tot_strat->register_ap(apname));
// right might be an input
if (std::find(input_aps.begin(), input_aps.end(), apname)
== input_aps.end())
additional_outputs &= right;
if (pos)
add &= bdd_biimp(left, right);
else
add &= bdd_xor(left, right);
}
}
for (auto& e: tot_strat->edges())
e.cond &= add;
set_synthesis_outputs(tot_strat,
get_synthesis_outputs(tot_strat)
& additional_outputs);
}
if (rs) // Add any AP we removed
rs->patch_mealy(tot_strat);
printer.print(tot_strat, timer_printer_dummy);
}