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prepare for tuned viable sets

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2021-06-30 01:05:34 -04:00
parent a0b0c1f428
commit a374e739f1
6 changed files with 165 additions and 38 deletions
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109
src/math/polysat/viable.cpp
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@ -10,6 +10,13 @@ Author:
Nikolaj Bjorner (nbjorner) 2021-03-19
Jakob Rath 2021-04-6
Notes:
Use cheap heuristics to narrow viable sets whenever possible.
If the cheap heuristics fail, compute a BDD representing the viable sets
and narrow the range using the BDDs that are cached.
--*/
#include "math/polysat/viable.h"
@ -23,16 +30,13 @@ namespace polysat {
dd::find_t viable_set::find_hint(rational const& d, rational& val) const {
if (is_empty())
return dd::find_t::empty;
//
// ignore d since with a single interval,
// backtracking does not ensure that non-boundary bounds are removed.
// viable_set could have multiple intervals to support arbitrary partitions
// this is similar to interval_set or might even be an instance of it.
//
val = lo;
return dd::find_t::empty;
if (contains(d))
val = d;
else
val = lo;
if (lo + 1 == hi || hi == 0 && is_max(lo))
return dd::find_t::singleton;
return dd::find_t::singleton;
return dd::find_t::multiple;
}
@ -40,7 +44,7 @@ namespace polysat {
return a + 1 == rational::power_of_two(m_num_bits);
}
bool viable_set::is_singleton(rational& val) const {
bool viable_set::is_singleton() const {
return !is_empty() && (lo + 1 == hi || (hi == 0 && is_max(lo)));
}
@ -60,9 +64,9 @@ namespace polysat {
return;
if (a == lo && a + 1 == hi)
set_empty();
if (a == lo && hi == 0 && is_max(a))
else if (a == lo && hi == 0 && is_max(a))
set_empty();
else if (a == lo)
else if (a == lo && !is_max(a))
lo = a + 1;
else if (a + 1 == hi)
hi = a;
@ -80,18 +84,20 @@ namespace polysat {
else {
rational a_inv;
VERIFY(a.mult_inverse(m_num_bits, a_inv));
intersect_eq(mod(a_inv * -b, rational::power_of_two(m_num_bits)), is_positive);
intersect_eq(mod(a_inv * -b, p2()), is_positive);
}
}
else
std::cout << "intersect " << a << "*x " << " == " << b << " " << is_positive << "\n";
}
void viable_set::intersect_ule(rational const& a, rational const& b, rational const& c, rational const& d, bool is_positive) {
bool viable_set::intersect_ule(rational const& a, rational const& b, rational const& c, rational const& d, bool is_positive) {
// x <= 0
if (a == 1 && b == 0 && c == 0 && d == 0)
if (a.is_odd() && b == 0 && c == 0 && d == 0)
intersect_eq(b, is_positive);
else if (a == 1 && b == 0 && c == 0) {
// x <= d
if (is_positive)
if (is_positive)
set_hi(d);
// x > d
else if (is_max(d))
@ -101,13 +107,38 @@ namespace polysat {
}
else if (a == 0 && c == 1 && d == 0) {
// x >= b
if (is_positive)
if (is_positive)
set_lo(b);
else if (b == 0)
set_empty();
else
else
set_hi(b - 1);
}
}
else if (c == 0 && d == 0) {
// ax + b <= 0
// or ax + b > 0
intersect_eq(a, b, is_positive);
}
else
return false;
return true;
}
void viable_set::intersect_ule(rational const& a, rational const& b, rational const& c, rational const& d, bool is_positive, unsigned& budget) {
auto eval = [&](rational const& x) {
return is_positive == mod(a * x + b, p2()) <= mod(c * x + d, p2());
};
while (budget > 0 && !eval(lo) && !is_max(lo) && !is_empty()) {
--budget;
lo += 1;
set_lo(lo);
}
while (budget > 0 && hi > 0 && !eval(hi - 1) && !is_empty()) {
--budget;
hi = hi - 1;
set_hi(hi);
}
}
void viable_set::set_hi(rational const& d) {
@ -136,11 +167,8 @@ namespace polysat {
#endif
viable::viable(solver& s):
s(s)
#if !NEW_VIABLE
,
s(s),
m_bdd(1000)
#endif
{}
void viable::push_viable(pvar v) {
@ -191,7 +219,35 @@ namespace polysat {
void viable::intersect_ule(pvar v, rational const& a, rational const& b, rational const& c, rational const& d, bool is_positive) {
#if NEW_VIABLE
push_viable(v);
m_viable[v].intersect_ule(a, b, c, d, is_positive);
if (!m_viable[v].intersect_ule(a, b, c, d, is_positive)) {
unsigned budget = 10;
m_viable[v].intersect_ule(a, b, c, d, is_positive, budget);
if (budget == 0) {
std::cout << "miss: " << a << " " << b << " " << c << " " << d << " " << is_positive << "\n";
unsigned sz = var2bits(v).num_bits();
bdd le = m_bdd.mk_true();
ineq_entry entry0(sz, a, b, c, d, le);
ineq_entry* other = nullptr;
if (!m_ineq_cache.find(&entry0, other)) {
std::cout << "ADD-to-cache\n";
bddv const& x = var2bits(v).var();
le = ((a * x) + b) <= ((c * x) + d);
other = alloc(ineq_entry, sz, a, b, c, d, le);
m_ineq_cache.insert(other);
}
le = is_positive ? other->repr : !other->repr;
other->m_activity++;
// le(lo) is false: find min x >= lo, such that le(x) is false, le(x+1) is true
// le(hi) is false: find max x =< hi, such that le(x) is false, le(x-1) is true
// bdd x_is_lo = m.mk_num(sz, m_viable[v].lo) == var2bits(v).var();
// bdd lo_is_sat = x_is_lo && lo;
// if (lo_is_sat.is_false())
// find_min_above(lo, le);
}
}
if (m_viable[v].is_empty())
s.set_conflict(v);
#else
@ -230,6 +286,7 @@ namespace polysat {
#if NEW_VIABLE
push_viable(v);
m_viable[v].set_ne(val);
std::cout << " v" << v << " != " << val << "\n";
if (m_viable[v].is_empty())
s.set_conflict(v);
#else
@ -257,7 +314,6 @@ namespace polysat {
#endif
}
#if !NEW_VIABLE
dd::fdd const& viable::sz2bits(unsigned sz) {
m_bits.reserve(sz + 1);
auto* bits = m_bits[sz];
@ -267,7 +323,6 @@ namespace polysat {
}
return *bits;
}
#endif
#if POLYSAT_LOGGING_ENABLED
void viable::log() {
@ -291,9 +346,7 @@ namespace polysat {
}
#endif
#if !NEW_VIABLE
dd::fdd const& viable::var2bits(pvar v) { return sz2bits(s.size(v)); }
#endif
}