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butterfly effect with relevancy marking

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bail out of infinite instantiation loop
This commit is contained in:
Nikolaj Bjorner 2021-02-15 16:37:23 -08:00
parent a6dce246f6
commit 823830181b
8 changed files with 45 additions and 33 deletions
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17
src/smt/seq_eq_solver.cpp
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@ -1321,23 +1321,34 @@ bool theory_seq::propagate_length_coherence(expr* e) {
expr_ref lo_e(m_autil.mk_numeral(lo, true), m);
expr_ref len_e_ge_lo(m_autil.mk_ge(mk_len(e), lo_e), m);
literal low = mk_literal(len_e_ge_lo);
add_axiom(~low, mk_seq_eq(e, tail));
literal eq = mk_seq_eq(e, tail);
bool added = false;
if (ctx.get_assignment(eq) != l_true) {
add_axiom(~low, eq);
added = true;
}
expr_ref len_e = mk_len(e);
if (upper_bound(len_e, hi)) {
// len(e) <= hi => len(tail) <= hi - lo
expr_ref high1(m_autil.mk_le(len_e, m_autil.mk_numeral(hi, true)), m);
if (hi == lo) {
add_axiom(~mk_literal(high1), mk_seq_eq(seq, emp));
added = true;
}
else {
expr_ref high2(m_autil.mk_le(mk_len(seq), m_autil.mk_numeral(hi-lo, true)), m);
add_axiom(~mk_literal(high1), mk_literal(high2));
literal h2 = mk_literal(high2);
if (ctx.get_assignment(h2) != l_true) {
add_axiom(~mk_literal(high1), h2);
added = true;
}
}
}
else {
assume_equality(seq, emp);
added = true;
}
return true;
return added;
}