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parity: add spot::parity_product()

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Compute the synchronized product of two parity automata, this product
keeps the parity acceptance.

* spot/twaalgos/parity.cc, spot/twaalgos/parity.hh: Here
* tests/core/parity.cc: Add tests for spot::parity_product()
This commit is contained in:
Laurent XU 2017-02-15 00:25:11 +01:00
parent 3e650f18d9
commit b92320cc33
3 changed files with 286 additions and 0 deletions
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216
spot/twaalgos/parity.cc
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@ -288,4 +288,220 @@ namespace spot
}
return aut;
}
namespace
{
class state_history : public std::vector<bool>
{
public:
state_history(unsigned left_num_sets, unsigned right_num_sets) :
left_num_sets_(left_num_sets),
right_num_sets_(right_num_sets)
{
resize(left_num_sets * right_num_sets * 2, false);
}
bool get_e(unsigned left, unsigned right) const
{
return get(left, right, true);
}
bool get_f(unsigned left, unsigned right) const
{
return get(left, right, false);
}
void set_e(unsigned left, unsigned right, bool val)
{
set(left, right, true, val);
}
void set_f(unsigned left, unsigned right, bool val)
{
set(left, right, false, val);
}
unsigned get_left_num_sets() const
{
return left_num_sets_;
}
unsigned get_right_num_sets() const
{
return right_num_sets_;
}
private:
unsigned left_num_sets_;
unsigned right_num_sets_;
bool get(unsigned left, unsigned right, bool first) const
{
return at(left * right_num_sets_ * 2 + right * 2 + (first ? 1 : 0));
}
void set(unsigned left, unsigned right, bool first, bool val)
{
at(left * right_num_sets_ * 2 + right * 2 + (first ? 1 : 0)) = val;
}
};
typedef std::tuple<unsigned, unsigned, state_history>
product_state;
struct product_state_hash
{
size_t
operator()(product_state s) const
{
auto result = wang32_hash(std::get<0>(s) ^ wang32_hash(std::get<1>(s)));
return result ^ (std::hash<std::vector<bool>>()(std::get<2>(s)) << 1);
}
};
twa_graph_ptr
parity_product_aux(twa_graph_ptr& left, twa_graph_ptr& right)
{
std::unordered_map<product_state, std::pair<unsigned, unsigned>,
product_state_hash> s2n;
std::queue<std::pair<product_state, unsigned>> todo;
auto res = make_twa_graph(left->get_dict());
res->copy_ap_of(left);
res->copy_ap_of(right);
unsigned left_num_sets = left->num_sets();
unsigned right_num_sets = right->num_sets();
unsigned z_size = left_num_sets + right_num_sets - 1;
auto z = acc_cond::acc_code::parity(true, false, z_size);
res->set_acceptance(z_size, z);
auto v = new product_states;
res->set_named_prop("product-states", v);
auto new_state =
[&](const state_history& current_history,
unsigned left_state, unsigned right_state,
unsigned left_acc_set, unsigned right_acc_set)
-> std::pair<unsigned, unsigned>
{
product_state x(left_state, right_state, current_history);
auto& mat = std::get<2>(x);
for (unsigned i = 0; i < left_num_sets; ++i)
for (unsigned j = 0; j < right_num_sets; ++j)
{
auto e_ij = current_history.get_e(i, j);
auto f_ij = current_history.get_f(i, j);
auto left_in_i = left_acc_set >= i;
auto right_in_j = right_acc_set >= j;
if (e_ij && f_ij)
{
mat.set_e(i, j, left_in_i);
mat.set_f(i, j, right_in_j);
}
else
{
mat.set_e(i, j, e_ij || left_in_i);
mat.set_f(i, j, f_ij || right_in_j);
}
}
auto p = s2n.emplace(x, std::make_pair(0, 0));
if (p.second) // This is a new state
{
p.first->second.first = res->new_state();
p.first->second.second = 0;
for (unsigned i = z_size - 1; i > 0
&& p.first->second.second == 0; --i)
{
// i is the index of the resulting automaton acceptance set
// If i is even, it means that the according set is a set with
// transitions that need to be infinitly often as the acceptance
// is a parity even. Then k, the index of the first automaton must
// be even too.
unsigned k = 0;
if (i >= right_num_sets)
k = i - right_num_sets + 1;
unsigned var = 2 - i % 2;
k += k & ~var & 1;
unsigned max_k = std::min(i + 1, left_num_sets);
while (k < max_k)
{
unsigned l = i - k;
if (mat.get_e(k, l) && mat.get_f(k, l))
{
p.first->second.second = i;
break;
}
k += var;
}
v->push_back(std::make_pair(left_state, right_state));
}
todo.emplace(x, p.first->second.first);
}
return p.first->second;
};
state_history init_state_history(left_num_sets, right_num_sets);
product_state init_state(left->get_init_state_number(),
right->get_init_state_number(),
init_state_history);
auto init_state_index = res->new_state();
s2n.emplace(init_state, std::make_pair(init_state_index, 0));
todo.emplace(init_state, init_state_index);
res->set_init_state(init_state_index);
while (!todo.empty())
{
auto& top = todo.front();
for (auto& l: left->out(std::get<0>(top.first)))
for (auto& r: right->out(std::get<1>(top.first)))
{
auto cond = l.cond & r.cond;
if (cond == bddfalse)
continue;
auto left_acc = l.acc.max_set() - 1;
auto right_acc = r.acc.max_set() - 1;
auto dst = new_state(std::get<2>(top.first), l.dst, r.dst,
left_acc, right_acc);
auto acc = acc_cond::mark_t{dst.second};
res->new_edge(top.second, dst.first, cond, acc);
}
todo.pop();
}
// 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
parity_product(const const_twa_graph_ptr& left,
const const_twa_graph_ptr& right)
{
if (left->get_dict() != right->get_dict())
throw std::runtime_error("parity_product: left and right automata "
"should share their bdd_dict");
if (!(left->is_existential() && right->is_existential()))
throw std::runtime_error("parity_product() does not support alternating "
"automata");
auto first = change_parity(left, parity_kind_max, parity_style_even);
auto second = change_parity(right, parity_kind_max, parity_style_even);
cleanup_parity_here(first, true);
cleanup_parity_here(second, true);
colorize_parity_here(first, true);
colorize_parity_here(second, true);
return parity_product_aux(first, second);
}
}