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fixes for #6590

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This commit is contained in:
Nikolaj Bjorner 2023-02-15 15:11:44 -08:00
parent c1ecc49021
commit 7c08e53e94
2 changed files with 17 additions and 9 deletions
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18
src/math/lp/nla_powers.cpp
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@ -79,6 +79,7 @@ am().set(rval, am_value(r));
namespace nla {
lbool powers::check(lpvar r, lpvar x, lpvar y, vector<lemma>& lemmas) {
TRACE("nla", tout << r << " == " << x << "^" << y << "\n");
if (x == null_lpvar || y == null_lpvar || r == null_lpvar)
return l_undef;
if (lp::tv::is_term(x) || lp::tv::is_term(y) || lp::tv::is_term(r))
@ -145,17 +146,24 @@ namespace nla {
auto r2val = power(xval, yval.get_unsigned());
if (rval == r2val)
return l_true;
if (xval > 0 && r2val < rval) {
SASSERT(yval > 0);
if (c.random() % 2 == 0) {
new_lemma lemma(c, "x == x0, y == y0 => r = x0^y0");
lemma |= ineq(x, llc::NE, xval);
lemma |= ineq(y, llc::NE, yval);
lemma |= ineq(r, llc::EQ, r2val);
return l_false;
}
if (yval > 0 && r2val > rval) {
new_lemma lemma(c, "x >= x0 > 0, y >= y0 > 0 => r >= x0^y0");
lemma |= ineq(x, llc::LT, xval);
lemma |= ineq(y, llc::LT, yval);
lemma |= ineq(r, llc::GE, r2val);
return l_false;
}
if (xval > 0 && r2val < rval) {
new_lemma lemma(c, "x >= x0 > 0, y <= y0 => r <= x0^y0");
lemma |= ineq(x, llc::LT, xval);
if (r2val < rval) {
new_lemma lemma(c, "0 < x <= x0, y <= y0 => r <= x0^y0");
lemma |= ineq(x, llc::LE, rational::zero());
lemma |= ineq(x, llc::GT, xval);
lemma |= ineq(y, llc::GT, yval);
lemma |= ineq(r, llc::LE, r2val);
return l_false;