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simplifications noticed by trying #4147

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The change masks possible bugs in smt.threads and arrays.
This commit is contained in:
Nikolaj Bjorner 2020-04-29 10:15:54 -07:00
parent 7cfd16c7f9
commit 3fc001baea
4 changed files with 25 additions and 10 deletions
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9
src/smt/seq_axioms.cpp
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@ -563,16 +563,15 @@ void seq_axioms::add_itos_axiom(expr* e) {
/**
stoi(s) >= -1
stoi("") = -1
stoi(s) >= 0 => len(s) > 0
stoi(s) >= 0 => is_digit(nth(s,0))
*/
void seq_axioms::add_stoi_axiom(expr* e) {
TRACE("seq", tout << mk_pp(e, m) << "\n";);
literal ge0 = mk_ge(e, 0);
expr* s = nullptr;
VERIFY (seq.str.is_stoi(e, s));
add_axiom(mk_ge(e, -1)); // stoi(s) >= -1
add_axiom(~mk_eq_empty(s), mk_eq(e, a.mk_int(-1))); // s = "" => stoi(s) = -1
literal ge0 = mk_ge(e, 0);
add_axiom(~ge0, is_digit(mk_nth(s, 0))); // stoi(s) >= 0 => is_digit(nth(s,0))
}
@ -614,9 +613,9 @@ void seq_axioms::add_stoi_axiom(expr* e, unsigned k) {
expr_ref len = mk_len(s);
literal ge0 = mk_ge(e, 0);
literal lek = mk_le(len, k);
add_axiom(~lek, mk_eq(e, stoi2(k-1))); // len(s) <= k => stoi(s) = stoi(s, k-1)
add_axiom(mk_le(len, 0), ~is_digit_(0), mk_eq(stoi2(0), digit(0))); // len(s) > 0, is_digit(nth(s, 0)) => stoi(s,0) = digit(s,0)
add_axiom(mk_le(len, 0), is_digit_(0), mk_eq(stoi2(0), a.mk_int(-1))); // len(s) > 0, ~is_digit(nth(s, 0)) => stoi(s,0) = -1
add_axiom(~lek, mk_eq(e, stoi2(k-1))); // len(s) <= k => stoi(s) = stoi(s, k-1)
add_axiom(mk_le(len, 0), ~is_digit_(0), mk_eq(stoi2(0), digit(0))); // len(s) > 0, is_digit(nth(s, 0)) => stoi(s,0) = digit(s,0)
add_axiom(mk_le(len, 0), is_digit_(0), mk_eq(stoi2(0), a.mk_int(-1))); // len(s) > 0, ~is_digit(nth(s, 0)) => stoi(s,0) = -1
for (unsigned i = 1; i < k; ++i) {
// len(s) <= i => stoi(s, i) = stoi(s, i - 1)