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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2021-05-06 09:26:08 -07:00
parent 5ca8295dcc
commit bd5aa2ac21
2 changed files with 68 additions and 3 deletions
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57
src/math/polysat/fixplex_def.h
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@ -396,6 +396,39 @@ namespace polysat {
return 0 < lo_sum && lo_sum <= hi_sum;
}
/**
* Check if row is infeasible modulo parity constraints.
* Let parity be the minimal power of two of coefficients to non-fixed variables.
* Let fixed be the sum of fixed variables.
* A row is infeasible if parity > the smallest power of two dividing fixed.
*
* Other parity tests are possible.
* The "range" parity test checks if the minimal parities of all but one variable are outside
* the range of the value range of a selected variable.
*/
template<typename Ext>
bool fixplex<Ext>::is_parity_infeasible_row(var_t x) {
SASSERT(is_base(x));
auto r = base2row(x);
if (row2integral(row(r)))
return false;
numeral fixed = 0;
unsigned parity = UINT_MAX;
for (auto const& e : M.row_entries(row(r))) {
var_t v = e.m_var;
auto c = e.m_coeff;
if (is_fixed(v))
fixed += value(v)*c;
else
parity = std::min(trailing_zeros(c), parity);
}
if (trailing_zeros(fixed) < parity)
return true;
return false;
}
/**
\brief Given row
@ -586,7 +619,7 @@ namespace polysat {
template<typename Ext>
void fixplex<Ext>::set_base_value(var_t x) {
SASSERT(is_base(x));
auto row r(base2row(x));
row r(base2row(x));
m_vars[x].m_value = 0 - (row2value(r) / row2base_coeff(r));
bool was_integral = row2integral(r);
m_rows[r.id()].m_integral = is_solved(r);
@ -596,6 +629,28 @@ namespace polysat {
--m_num_non_integral;
}
/**
* Equality detection.
*/
template<typename Ext>
bool fixplex<Ext>::is_offset_row(row const& r, var_t& x, var_t & y) const {
x = null_var;
y = null_var;
for (auto const& e : M.row_entries(r)) {
var_t v = e.m_var;
if (is_fixed(v))
continue;
numeral const& c = e.m_coeff;
if (c == 1 && x == null_var)
x = v;
else if (c + 1 == 0 && y == null_var)
y = v;
else
return false;
}
return true;
}
template<typename Ext>
std::ostream& fixplex<Ext>::display(std::ostream& out) const {