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initial outline of exponentiation

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2023-01-23 17:38:34 -08:00
parent 3032c9315d
commit 2ae476416c
4 changed files with 207 additions and 116 deletions
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67
src/smt/theory_lra.cpp
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@ -797,8 +797,17 @@ class theory_lra::imp {
return internalize_linearized_def(term, st);
}
lpvar get_lpvar(expr* e) {
return get_lpvar(get_enode(e));
}
lpvar get_lpvar(enode* n) {
ensure_column(n);
return n ? get_lpvar(n->get_th_var(get_id())) : lp::null_lpvar;
}
lpvar get_lpvar(theory_var v) const {
return lp().external_to_local(v);
return v == null_theory_var ? lp::null_lpvar : lp().external_to_local(v);
}
lp::tv get_tv(theory_var v) const {
@ -1424,10 +1433,13 @@ public:
return v != null_theory_var && lp().external_is_used(v);
}
void ensure_column(enode* n) {
ensure_column(n->get_th_var(get_id()));
}
void ensure_column(theory_var v) {
if (!lp().external_is_used(v)) {
if (!lp().external_is_used(v) && v != null_theory_var)
register_theory_var_in_lar_solver(v);
}
}
mutable vector<std::pair<lp::tv, rational>> m_todo_terms;
@ -1570,47 +1582,18 @@ public:
final_check_status eval_power(expr* e) {
expr* x, * y;
VERIFY(a.is_power(e, x, y));
enode* n = get_enode(e);
enode* xn = get_enode(x);
enode* yn = get_enode(y);
if (!n || !xn || !yn)
return FC_GIVEUP;
rational valx, valy, valn;
theory_var v = n->get_th_var(get_id());
if (!get_value(xn, valx))
return FC_GIVEUP;
if (!get_value(yn, valy))
return FC_GIVEUP;
if (!get_value(n, valn))
return FC_GIVEUP;
// TBD - check that values align so return FC_DONE.
if (valn < 0 && valx > 0 && valy > 0) {
mk_axiom(mk_literal(a.mk_le(x, a.mk_numeral(rational(0), x->get_sort()))),
~mk_literal(a.mk_le(e, a.mk_numeral(rational(0), e->get_sort()))));
switch (m_nla->check_power(get_lpvar(e), get_lpvar(x), get_lpvar(y), m_nla_lemma_vector)) {
case l_true:
return FC_DONE;
case l_false:
for (const nla::lemma & l : m_nla_lemma_vector)
false_case_of_check_nla(l);
return FC_CONTINUE;
}
// add tangent lemmas for power:
// establish equality using algebraic numerals
// appears to be useless:
if (false && !valy.is_int() && numerator(valy) == 1 && denominator(valy) > 0) {
rational d = denominator(valy);
if (!d.is_unsigned())
return FC_GIVEUP;
unsigned den = d.get_unsigned();
// e = x^{1/y}
// => e^y = x
ptr_vector<expr> es;
for (unsigned i = 0; i < den; ++i)
es.push_back(e);
expr* em = a.mk_mul(es.size(), es.data());
mk_axiom(~mk_literal(m.mk_eq(y, a.mk_real(valy))), mk_literal(m.mk_eq(em, x)));
return FC_CONTINUE;
case l_undef:
return FC_GIVEUP;
default:
break;
}
return FC_GIVEUP;
}