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working on pivot

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2021-04-20 17:42:01 -07:00
parent 80751bdd12
commit 36cd80748f
6 changed files with 74 additions and 55 deletions
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93
src/math/polysat/fixplex_def.h
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@ -46,6 +46,8 @@ namespace polysat {
m_row2base.reset();
m_left_basis.reset();
m_base_vars.reset();
pivot(0,1, 2);
}
template<typename Ext>
@ -129,32 +131,14 @@ namespace polysat {
}
/**
* make v a basic variable.
* If v is already a basic variable in preferred_row, skip
* If v
* If v is non-basic but basic in a different row, then
* eliminate v from one of the rows.
* If v if non-basic
*/
template<typename Ext>
void fixplex<Ext>::make_basic(var_t v, row const& preferred_row) {
numeral c1 = 0;
for (auto const& e : M.row_entries(preferred_row)) {
if (e.m_var == v) {
c1 = e.m_coeff;
break;
}
}
auto c2 = m_vars[v].m_base_coeff;
auto r2 = m_vars[v].m_base2row;
unsigned exp1 = trailing_zeros(c1); // exponent of two for v in r
unsigned exp2 = trailing_zeros(c2); // exponent of two for v in r2
if (exp1 >= exp2) {
// eliminate v from r
}
else {
// eliminate v from r2,
// make v the new base for r
// perform gauss-jordan for both r and r2 (add to queue)
}
NOT_IMPLEMENTED_YET();
@ -189,43 +173,64 @@ namespace polysat {
SASSERT(new_value == x_iI.m_value);
pivot(x_i, x_j, a_ij);
}
#endif
template<typename Ext>
void fixplex<Ext>::pivot(var_t x_i, var_t x_j, numeral const& a_ij) {
void fixplex<Ext>::pivot(var_t x_i, var_t x_j, numeral a_ij) {
++m_stats.m_num_pivots;
var_info& x_iI = m_vars[x_i];
var_info& x_jI = m_vars[x_j];
unsigned r_i = x_iI.m_base2row;
m_row2base[r_i] = x_j;
x_jI.m_base2row = r_i;
x_jI.m_base_coeff = a_ij;
unsigned ri = x_iI.m_base2row;
m_row2base[ri] = x_j;
x_jI.m_base2row = ri;
x_jI.m_is_base = true;
x_iI.m_is_base = false;
row r_i(ri);
add_patch(x_j);
SASSERT(well_formed_row(row(r_i)));
SASSERT(well_formed_row(r_i));
col_iterator it = M.col_begin(x_j), end = M.col_end(x_j);
scoped_numeral a_kj(m), g(m);
for (; it != end; ++it) {
row r_k = it.get_row();
if (r_k.id() != r_i) {
a_kj = it.get_row_entry().m_coeff;
a_kj.neg();
M.mul(r_k, a_ij);
M.add(r_k, a_kj, row(r_i));
var_t s = m_row2base[r_k.id()];
numeral& coeff = m_vars[s].m_base_coeff;
m.mul(coeff, a_ij, coeff);
M.gcd_normalize(r_k, g);
if (!m.is_one(g)) {
m.div(coeff, g, coeff);
}
SASSERT(well_formed_row(row(r_k)));
unsigned tz1 = trailing_zeros(a_ij);
for (auto c : M.col_entries(x_j)) {
row r_k = c.get_row();
unsigned rk = r_k.id();
if (rk == ri)
continue;
numeral a_kj = c.get_row_entry().m_coeff;
unsigned tz2 = trailing_zeros(a_kj);
if (tz2 >= tz1) {
// eliminate x_j from row r_k
numeral a = a_ij >> tz1;
numeral b = m.inv(a_kj >> (tz2 - tz1));
M.mul(r_k, a);
M.add(r_k, b, r_i);
}
else {
// eliminate x_j from row r_i
// The new base variable for r_i is base of r_k
// The new base variable for r_k is x_j.
numeral a = a_kj >> tz2;
numeral b = m.inv(a_ij >> (tz1 - tz2));
M.mul(r_i, a);
M.add(r_i, b, r_k);
unsigned x_k = m_row2base[rk];
std::swap(m_row2base[ri], m_row2base[rk]);
m_vars[x_j].m_base2row = rk;
m_vars[x_k].m_base2row = ri;
tz1 = tz2;
r_i = r_k;
ri = rk;
a_ij = a_kj;
}
SASSERT(well_formed_row(r_k));
}
SASSERT(well_formed());
}
#if 0
template<typename Ext>
void fixplex<Ext>::update_value(var_t v, eps_numeral const& delta) {
if (em.is_zero(delta)) {