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Guard mod constraint: skip for period <= 1

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Co-authored-by: NikolajBjorner <3085284+NikolajBjorner@users.noreply.github.com>
This commit is contained in:
copilot-swe-agent[bot] 2026-03-10 20:14:53 +00:00
parent 2bae0f02c4
commit 334e6da60d
1 changed files with 19 additions and 15 deletions
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34
src/smt/theory_seq_len.cpp
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@ -331,7 +331,7 @@ namespace smt {
// Semi-linear: lengths are {base + k * period : k >= 0}
// Assert:
// (s in R) => |s| >= base
// (s in R) => |s| mod period = base mod period
// (s in R) => |s| mod period = base mod period (only when period >= 2)
// |s| >= base
expr_ref ge_base(m_autil.mk_ge(len, m_autil.mk_int(base)), m);
@ -347,22 +347,26 @@ namespace smt {
}
// |s| mod period = base mod period
expr_ref mod_len(m_autil.mk_mod(len, m_autil.mk_int(period)), m);
expr_ref eq_mod(m.mk_eq(mod_len, m_autil.mk_int(base % period)), m);
if (!ctx.b_internalized(eq_mod))
ctx.internalize(eq_mod, true);
literal eq_mod_lit = ctx.get_literal(eq_mod);
ctx.mark_as_relevant(eq_mod_lit);
{
literal_vector lits;
lits.push_back(~lit);
lits.push_back(eq_mod_lit);
assert_axiom(lits);
// Skip when period <= 1: period == 0 is already handled above;
// period == 1 makes the constraint trivially true (n mod 1 = 0).
if (period >= 2) {
expr_ref mod_len(m_autil.mk_mod(len, m_autil.mk_int(period)), m);
expr_ref eq_mod(m.mk_eq(mod_len, m_autil.mk_int(base % period)), m);
if (!ctx.b_internalized(eq_mod))
ctx.internalize(eq_mod, true);
literal eq_mod_lit = ctx.get_literal(eq_mod);
ctx.mark_as_relevant(eq_mod_lit);
{
literal_vector lits;
lits.push_back(~lit);
lits.push_back(eq_mod_lit);
assert_axiom(lits);
}
}
TRACE(seq, tout << "seq_len: (s in R) => |s| >= " << base << " && |s| mod "
<< period << " = " << (base % period) << " for s=" << mk_pp(s, m)
<< " r=" << mk_pp(r, m) << "\n";);
TRACE(seq, tout << "seq_len: (s in R) => |s| >= " << base
<< (period >= 2 ? " && |s| mod " + std::to_string(period) + " = " + std::to_string(base % period) : "")
<< " for s=" << mk_pp(s, m) << " r=" << mk_pp(r, m) << "\n";);
}
}