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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2021-11-10 00:43:57 -08:00
parent d0c8240560
commit d0b47d23f6
2 changed files with 71 additions and 11 deletions
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75
src/math/polysat/forbidden_intervals.cpp
View file

@ -175,8 +175,7 @@ namespace polysat {
* \returns True iff a forbidden interval exists and the output parameters were set.
*/
bool forbidden_intervals::get_interval(signed_constraint const& c, pvar v, eval_interval& out_interval, vector<signed_constraint>& out_side_cond)
{
bool forbidden_intervals::get_interval(signed_constraint const& c, pvar v, eval_interval& out_interval, vector<signed_constraint>& out_side_cond) {
if (!c->is_ule())
return false;
@ -218,12 +217,14 @@ namespace polysat {
return true;
if (match_linear3(c, a1, b1, e1, a2, b2, e2, out_interval, out_side_cond))
return true;
if (match_linear4(c, a1, b1, e1, a2, b2, e2, out_interval, out_side_cond))
return true;
_backtrack.released = false;
return false;
}
void forbidden_intervals::push_condition(bool is_zero, pdd const& p, vector<signed_constraint>& side_cond) {
void forbidden_intervals::push_eq(bool is_zero, pdd const& p, vector<signed_constraint>& side_cond) {
SASSERT(!p.is_val() || (is_zero == p.is_zero()));
if (p.is_val())
return;
@ -309,7 +310,7 @@ namespace polysat {
if (a2.is_zero() && coefficient_is_01(e1.manager(), a1)) {
SASSERT(!a1.is_zero());
bool is_trivial = (b2 + 1).is_zero();
push_condition(is_trivial, e2 + 1, side_cond);
push_eq(is_trivial, e2 + 1, side_cond);
auto lo = e2 - e1 + 1;
auto lo_val = (b2 - b1 + 1).val();
auto hi = -e1;
@ -331,7 +332,7 @@ namespace polysat {
if (a1.is_zero() && coefficient_is_01(e1.manager(), a2)) {
SASSERT(!a2.is_zero());
bool is_trivial = b1.is_zero();
push_condition(is_trivial, e1, side_cond);
push_eq(is_trivial, e1, side_cond);
auto lo = -e2;
auto lo_val = (-b2).val();
auto hi = e1 - e2;
@ -352,7 +353,7 @@ namespace polysat {
eval_interval& interval, vector<signed_constraint>& side_cond) {
if (coefficient_is_01(e1.manager(), a1) && coefficient_is_01(e1.manager(), a2) && a1 == a2 && !a1.is_zero()) {
bool is_trivial = b1.val() == b2.val();
push_condition(is_trivial, e1 - e2, side_cond);
push_eq(is_trivial, e1 - e2, side_cond);
auto lo = -e2;
auto lo_val = (-b2).val();
auto hi = -e1;
@ -363,15 +364,69 @@ namespace polysat {
return false;
}
// TBD:
// additional forbidden intervals for siutations like a*x <= b,
// then values for x can be discarded when a*x does not overflow and a*x > b.
//
/**
* a1*y + e1 = 0, with a1 odd
*/
bool forbidden_intervals::match_linear4(signed_constraint const& c,
rational const& a1, pdd const& b1, pdd const& e1,
rational const& a2, pdd const& b2, pdd const& e2,
eval_interval& interval, vector<signed_constraint>& side_cond) {
if (a1.is_odd() && a2.is_zero() && b2.val().is_zero()) {
push_eq(false, e2, side_cond);
rational a_inv, pow2 = e1.manager().max_value() + 1;
VERIFY(a1.mult_inverse(e1.manager().power_of_2(), a_inv));
auto lo = -e1 * a_inv;
auto lo_val = mod(-b1.val() * a_inv, pow2);
auto hi = lo + 1;
auto hi_val = mod(lo_val + 1, pow2);
interval = to_interval(c, false, rational::one(), lo_val, lo, hi_val, hi);
return true;
}
return false;
}
/**
* ax <= b, b != -1, a < b: x not in [ceil((b+1)/a) .. floor((2^K-1)/a)]
* b <= ax, 0 < a < b: x not in [0 .. floor((b-1)/a)]
* ax < b, a < b: x not in [ceil(b/a) .. floor((2^K-1)/a)]
* b < ax, 0 < a <= b: x not in [0 .. floor(b/a)]
*/
bool forbidden_intervals::match_linear5(signed_constraint const& c,
rational const& a1, pdd const& b1, pdd const& e1,
rational const& a2, pdd const& b2, pdd const& e2,
eval_interval& interval, vector<signed_constraint>& side_cond) {
auto& m = e1.manager();
if (c.is_positive() &&
!a1.is_zero() && !a1.is_one() &&
a2.is_zero() && b1.is_zero() && e2.is_val() &&
a1 < b2.val() && b2.val() != m.max_value()) {
if (!e1.is_val())
side_cond.push_back(s.eq(e1));
auto lo_val = ceil((b2.val() + 1) / a1);
auto hi_val = floor(m.max_value() / a1) + 1;
auto lo = m.mk_val(lo_val);
auto hi = m.mk_val(hi_val);
interval = eval_interval::proper(lo, lo_val, hi, hi_val);
return true;
}
if (c.is_positive() &&
!a2.is_zero() && !a2.is_one() &&
a1.is_zero() && b2.is_zero() &&
a2 < b1.val() && e1.is_val()) {
if (!e2.is_val())
side_cond.push_back(s.eq(e2));
auto lo_val = rational::zero();
auto hi_val = floor((b1.val() - 1) / a2) + 1;
auto lo = m.mk_val(lo_val);
auto hi = m.mk_val(hi_val);
interval = eval_interval::proper(lo, lo_val, hi, hi_val);
return true;
}
if (c.is_negative() &&
!a2.is_zero() && !a2.is_one() &&
a1.is_zero() && false) {
}
return false;
}

7
src/math/polysat/forbidden_intervals.h
View file

@ -24,7 +24,7 @@ namespace polysat {
void revert_core(conflict& core);
void full_interval_conflict(signed_constraint c, vector<signed_constraint> const & side_cond, conflict& core);
bool get_interval(signed_constraint const& c, pvar v, eval_interval& out_interval, vector<signed_constraint>& side_cond);
void push_condition(bool is_trivial, pdd const& p, vector<signed_constraint>& side_cond);
void push_eq(bool is_trivial, pdd const& p, vector<signed_constraint>& side_cond);
eval_interval to_interval(signed_constraint const& c, bool is_trivial, rational const& coeff,
rational & lo_val, pdd & lo, rational & hi_val, pdd & hi);
@ -51,6 +51,11 @@ namespace polysat {
rational const& a2, pdd const& b2, pdd const& e2,
eval_interval& interval, vector<signed_constraint>& side_cond);
bool match_linear5(signed_constraint const& c,
rational const& a1, pdd const& b1, pdd const& e1,
rational const& a2, pdd const& b2, pdd const& e2,
eval_interval& interval, vector<signed_constraint>& side_cond);
bool coefficient_is_01(dd::pdd_manager& m, rational const& r) { return r.is_zero() || r.is_one() || r == m.max_value(); };
public:
forbidden_intervals(solver& s) :s(s) {}