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Nikolaj implemented lm_lt on dd::pdd

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Signed-off-by: Lev Nachmanson <levnach@hotmail.com>
This commit is contained in:
Lev Nachmanson 2020-01-09 09:57:19 -08:00
parent d1e9998332
commit d6a246777a
5 changed files with 224 additions and 92 deletions
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49
src/math/dd/dd_pdd.cpp
View file

@ -495,12 +495,9 @@ namespace dd {
}
/*.
* The pdd format makes lexicographic comparison easy: compare based on
* the top variable and descend depending on whether hi(x) == hi(y)
*
* NB. this does not compare leading monomials.
* compare pdds based on leading monomials
*/
bool pdd_manager::lt(pdd const& a, pdd const& b) {
bool pdd_manager::lex_lt(pdd const& a, pdd const& b) {
PDD x = a.root;
PDD y = b.root;
if (x == y) return false;
@ -526,6 +523,48 @@ namespace dd {
}
}
bool pdd_manager::lm_lt(pdd const& a, pdd const& b) {
PDD x = first_leading(a.root);
PDD y = first_leading(b.root);
while (true) {
if (x == y) break;
if (is_val(x) && is_val(y)) break;
if (is_val(x)) return true;
if (is_val(y)) return false;
if (level(x) == level(y)) {
x = next_leading(x);
y = next_leading(y);
}
else {
return level(x) < level(y);
}
}
vector<unsigned_vector> ma, mb;
for (auto const& m : a) {
ma.push_back(m.vars);
}
for (auto const& m : b) {
mb.push_back(m.vars);
}
std::function<bool (unsigned_vector const& a, unsigned_vector const& b)> degree_lex_gt =
[this](unsigned_vector const& a, unsigned_vector const& b) {
unsigned i = 0;
if (a.size() > b.size()) return true;
if (a.size() < b.size()) return false;
for (; i < a.size() && a[i] == b[i]; ++i) {};
return i < a.size() && m_var2level[a[i]] > m_var2level[b[i]];
};
std::sort(ma.begin(), ma.end(), degree_lex_gt);
std::sort(mb.begin(), mb.end(), degree_lex_gt);
auto ita = ma.begin();
auto itb = mb.begin();
for (; ita != ma.end() && itb != mb.end(); ++ita, ++itb) {
if (degree_lex_gt(*itb, *ita)) return true;
if (degree_lex_gt(*ita, *itb)) return false;
}
return ita == ma.end() && itb != mb.end();
}
/**
Compare leading terms of pdds
*/

10
src/math/dd/dd_pdd.h
View file

@ -290,7 +290,12 @@ namespace dd {
// create an spoly r if leading monomials of a and b overlap
bool try_spoly(pdd const& a, pdd const& b, pdd& r);
bool lt(pdd const& a, pdd const& b);
// simple lexicographic comparison
bool lex_lt(pdd const& a, pdd const& b);
// more elaborate comparison based on leading monomials
bool lm_lt(pdd const& a, pdd const& b);
bool different_leading_term(pdd const& a, pdd const& b);
double tree_size(pdd const& p);
unsigned num_vars() const { return m_var2pdd.size(); }
@ -352,9 +357,6 @@ namespace dd {
std::ostream& display(std::ostream& out) const { return m.display(out, *this); }
bool operator==(pdd const& other) const { return root == other.root; }
bool operator!=(pdd const& other) const { return root != other.root; }
bool operator<(pdd const& other) const { return m.lt(*this, other); }
unsigned dag_size() const { return m.dag_size(*this); }
double tree_size() const { return m.tree_size(*this); }