mirrors/z3
3
0
Fork 0
mirror of https://github.com/Z3Prover/z3 synced 2025-04-24 17:45:32 +00:00
Code Activity

na

Browse source 
Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2021-05-06 10:51:42 -07:00
parent bd5aa2ac21
commit 253c954094
2 changed files with 99 additions and 18 deletions
Download patch file Download diff file Expand all files Collapse all files

29
src/math/polysat/fixplex.h
View file

@ -30,11 +30,15 @@ namespace polysat {
template<typename Ext>
class fixplex {
public:
typedef typename Ext::numeral numeral;
typedef typename Ext::scoped_numeral scoped_numeral;
typedef typename Ext::manager manager;
typedef simplex::sparse_matrix<Ext> matrix;
typedef typename matrix::row row;
typedef typename matrix::row_iterator row_iterator;
typedef typename matrix::col_iterator col_iterator;
protected:
struct var_lt {
bool operator()(var_t v1, var_t v2) const { return v1 < v2; }
};
@ -76,6 +80,13 @@ namespace polysat {
numeral m_base_coeff;
};
struct offset_eq {
var_t x, y;
row r1, r2;
offset_eq(var_t x, var_t y, row const& r1, row const& r2):
x(x), y(y), r1(r1), r2(r2) {}
};
static const var_t null_var = UINT_MAX;
reslimit& m_limit;
mutable manager m;
@ -85,6 +96,7 @@ namespace polysat {
var_heap m_to_patch;
vector<var_info> m_vars;
vector<row_info> m_rows;
vector<offset_eq> m_offset_eqs;
bool m_bland { false };
unsigned m_blands_rule_threshold { 1000 };
random_gen m_random;
@ -101,9 +113,6 @@ namespace polysat {
~fixplex();
typedef typename matrix::row row;
typedef typename matrix::row_iterator row_iterator;
typedef typename matrix::col_iterator col_iterator;
void set_bounds(var_t v, numeral const& lo, numeral const& hi);
void unset_bounds(var_t v) { m_vars[v].m_lo = m_vars[v].m_hi; }
@ -141,7 +150,10 @@ namespace polysat {
lbool make_var_feasible(var_t x_i);
bool is_infeasible_row(var_t x);
bool is_parity_infeasible_row(var_t x);
bool is_offset_row(row const& r, var_t& x, var_t & y) const;
bool is_offset_row(row const& r, numeral& cx, var_t& x, numeral& cy, var_t & y) const;
void lookahead_eq(row const& r1, numeral const& cx, var_t x, numeral const& cy, var_t y);
void get_offset_eqs(row const& r);
void eq_eh(var_t x, var_t y, row const& r1, row const& r2);
void pivot(var_t x_i, var_t x_j, numeral const& b, numeral const& value);
numeral value2delta(var_t v, numeral const& new_value) const;
void update_value(var_t v, numeral const& delta);
@ -153,6 +165,7 @@ namespace polysat {
bool in_bounds(numeral const& val, numeral const& lo, numeral const& hi) const;
bool is_free(var_t v) const { return lo(v) == hi(v); }
bool is_non_free(var_t v) const { return !is_free(v); }
bool is_fixed(var_t v) const { return lo(v) + 1 == hi(v); }
bool is_base(var_t x) const { return m_vars[x].m_is_base; }
unsigned base2row(var_t x) const { return m_vars[x].m_base2row; }
numeral const& row2value(row const& r) const { return m_rows[r.id()].m_value; }
@ -198,6 +211,7 @@ namespace polysat {
void del(numeral const& n) {}
bool is_zero(numeral const& n) const { return n == 0; }
bool is_one(numeral const& n) const { return n == 1; }
bool is_even(numeral const& n) const { return (n & 1) == 0; }
bool is_minus_one(numeral const& n) const { return max_numeral == n; }
void add(numeral const& a, numeral const& b, numeral& r) { r = a + b; }
void sub(numeral const& a, numeral const& b, numeral& r) { r = a - b; }
@ -206,6 +220,7 @@ namespace polysat {
void neg(numeral& a) { a = 0 - a; }
numeral inv(numeral const& a) { return 0 - a; }
void swap(numeral& a, numeral& b) { std::swap(a, b); }
unsigned trailing_zeros(numeral const& a) const { return ::trailing_zeros(a); }
// treat numerals as signed and check for overflow/underflow
bool signed_mul(numeral& r, numeral const& x, numeral const& y) {
@ -218,7 +233,9 @@ namespace polysat {
r = x + y;
return x <= r;
}
std::ostream& display(std::ostream& out, numeral const& x) const { return out << x; }
std::ostream& display(std::ostream& out, numeral const& x) const {
return out << x;
}
};
typedef _scoped_numeral<manager> scoped_numeral;
};

88
src/math/polysat/fixplex_def.h
View file

@ -215,8 +215,12 @@ namespace polysat {
else
return l_undef;
}
pivot(x, y, b, new_value);
get_offset_eqs(row(base2row(y)));
return l_true;
}
@ -345,12 +349,12 @@ namespace polysat {
*/
template<typename Ext>
bool fixplex<Ext>::has_minimal_trailing_zeros(var_t y, numeral const& b) {
unsigned tz1 = trailing_zeros(b);
unsigned tz1 = m.trailing_zeros(b);
if (tz1 == 0)
return true;
for (auto col : M.col_entries(y)) {
numeral c = col.get_row_entry().m_coeff;
unsigned tz2 = trailing_zeros(c);
unsigned tz2 = m.trailing_zeros(c);
if (tz1 > tz2)
return false;
}
@ -420,10 +424,10 @@ namespace polysat {
if (is_fixed(v))
fixed += value(v)*c;
else
parity = std::min(trailing_zeros(c), parity);
parity = std::min(m.trailing_zeros(c), parity);
}
if (trailing_zeros(fixed) < parity)
if (m.trailing_zeros(fixed) < parity)
return true;
return false;
@ -484,7 +488,7 @@ namespace polysat {
add_patch(y);
SASSERT(well_formed_row(r_x));
unsigned tz1 = trailing_zeros(b);
unsigned tz1 = m.trailing_zeros(b);
for (auto col : M.col_entries(y)) {
row r_z = col.get_row();
@ -495,7 +499,7 @@ namespace polysat {
auto& row_z = m_rows[rz];
var_info& zI = m_vars[z];
numeral c = col.get_row_entry().m_coeff;
unsigned tz2 = trailing_zeros(c);
unsigned tz2 = m.trailing_zeros(c);
SASSERT(tz1 <= tz2);
numeral b1 = b >> tz1;
numeral c1 = m.inv(c >> (tz2 - tz1));
@ -631,24 +635,83 @@ namespace polysat {
/**
* Equality detection.
*
* Offset equality detection
* -------------------------
* is_offset_row: determine if row is cx*x + cy*y + k == 0 where k is a constant.
* Then walk every row containing x, y, respectively
* If there is a row cx*x + cy*z + k' == 0, where y, z are two different variables
* but value(y) = value(z), cy is odd
* then it follows that k = k' and y = z is implied.
*
* Offset equality detection is only applied to integral rows where the current
* evaluation satisfies the row equality.
*
* Fixed variable equalities
* -------------------------
*
*/
template<typename Ext>
bool fixplex<Ext>::is_offset_row(row const& r, var_t& x, var_t & y) const {
void fixplex<Ext>::get_offset_eqs(row const& r) {
var_t x, y;
numeral cx, cy;
if (!is_offset_row(r, cx, x, cy, y))
return;
lookahead_eq(r, cx, x, cy, y);
lookahead_eq(r, cy, y, cx, x);
}
template<typename Ext>
bool fixplex<Ext>::is_offset_row(row const& r, numeral& cx, var_t& x, numeral& cy, var_t & y) const {
x = null_var;
y = null_var;
if (!row2integral(r))
return false;
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)
if (x == null_var) {
cx = c;
x = v;
else if (c + 1 == 0 && y == null_var)
}
else if (y == null_var) {
cy = c;
y = v;
}
else
return false;
}
return true;
return y != null_var;
}
template<typename Ext>
void fixplex<Ext>::lookahead_eq(row const& r1, numeral const& cx, var_t x, numeral const& cy, var_t y) {
if (m.is_even(cy))
return;
var_t z, u;
numeral cz, cu;
for (auto c : M.col_entries(x)) {
auto r2 = c.get_row();
if (r1.id() == r2.id())
continue;
if (!is_offset_row(r2, cz, z, cu, u))
continue;
if (u == x) {
std::swap(z, u);
std::swap(cz, cu);
}
if (z == x && cx == cz && u != y && cu == cy && value(u) == value(y))
eq_eh(u, y, r1, r2);
}
}
template<typename Ext>
void fixplex<Ext>::eq_eh(var_t x, var_t y, row const& r1, row const& r2) {
m_offset_eqs.push_back(offset_eq(x, y, r1, r2));
}
@ -681,11 +744,12 @@ namespace polysat {
bool fixplex<Ext>::well_formed() const {
SASSERT(M.well_formed());
for (unsigned i = 0; i < m_rows.size(); ++i) {
var_t s = m_rows[i].m_base;
row r(i);
var_t s = row2base(r);
if (s == null_var)
continue;
SASSERT(i == base2row(s));
VERIFY(well_formed_row(row(i)));
VERIFY(well_formed_row(r));
}
for (unsigned i = 0; i < m_vars.size(); ++i) {
SASSERT(is_base(i) || in_bounds(i));