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fix and optimize not-contains and regex equalities

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2026-04-21 09:16:00 +02:00
parent c18188cba8
commit 352b14fe2b
4 changed files with 86 additions and 42 deletions
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12
src/ast/rewriter/seq_axioms.cpp
View file

@ -1353,11 +1353,23 @@ namespace seq {
Create the recursive function not_contains that implements this recursive definition.
Add the axiom
contains(a, b) or not_contains(a, b)
if b is a string (or concatentation of characters/unit values) use regex shortcut:
~contain(a, b) => a not in .*b.*
*/
void axioms::not_contains_axiom(expr *e) {
expr* _a = nullptr, *_b = nullptr;
VERIFY(seq.str.is_contains(e, _a, _b));
if (seq.str.is_string(_b)) {
auto star = seq.re.mk_full_seq(seq.re.mk_re(_b->get_sort()));
auto b_re = seq.re.mk_to_re(_b);
auto r = seq.re.mk_concat(star, seq.re.mk_concat(b_re, star));
auto mem = seq.re.mk_in_re(_a, r);
add_clause(expr_ref(e, m), ~expr_ref(mem, m));
return;
}
auto ca = purify(_a);
auto cb = purify(_b);
sort* srt = ca->get_sort();

44
src/smt/seq/seq_nielsen.cpp
View file

@ -866,8 +866,7 @@ namespace seq {
// pass 2: detect symbol clashes, empty-propagation, and prefix cancellation
for (str_eq& eq : m_str_eq) {
if (!eq.m_lhs || !eq.m_rhs)
continue;
SASSERT(eq.well_formed());
// one side empty, the other not empty => conflict check
// (the actual substitution is done in apply_det_modifier)
@ -1915,8 +1914,7 @@ namespace seq {
for (str_eq const& eq : node->str_eqs()) {
if (eq.is_trivial())
continue;
if (!eq.m_lhs || !eq.m_rhs)
continue;
SASSERT(eq.well_formed());
for (unsigned od = 0; od < 2; ++od) {
bool fwd = (od == 0);
euf::snode* lhead = dir_token(eq.m_lhs, fwd);
@ -1951,8 +1949,7 @@ namespace seq {
for (str_eq const& eq : node->str_eqs()) {
if (eq.is_trivial())
continue;
if (!eq.m_lhs || !eq.m_rhs)
continue;
SASSERT(eq.well_formed());
for (unsigned od = 0; od < 2; ++od) {
bool fwd = od == 0;
euf::snode* lhead = dir_token(eq.m_lhs, fwd);
@ -2189,8 +2186,7 @@ namespace seq {
str_eq const& eq = node->str_eqs()[eq_idx];
if (eq.is_trivial())
continue;
if (!eq.m_lhs || !eq.m_rhs)
continue;
SASSERT(eq.well_formed());
// EqSplit only applies to regex-free equations.
if (!eq.m_lhs->is_regex_free() || !eq.m_rhs->is_regex_free())
continue;
@ -2368,8 +2364,7 @@ namespace seq {
for (str_eq const& eq : node->str_eqs()) {
if (eq.is_trivial())
continue;
if (!eq.m_lhs || !eq.m_rhs)
continue;
SASSERT(eq.well_formed());
euf::snode_vector toks;
eq.m_lhs->collect_tokens(toks);
for (euf::snode* t : toks) {
@ -2399,8 +2394,7 @@ namespace seq {
for (str_eq const& eq : node->str_eqs()) {
if (eq.is_trivial())
continue;
if (!eq.m_lhs || !eq.m_rhs)
continue;
SASSERT(eq.well_formed());
for (unsigned od = 0; od < 2; ++od) {
bool local_fwd = (od == 0);
euf::snode* lhead = dir_token(eq.m_lhs, local_fwd);
@ -2439,7 +2433,7 @@ namespace seq {
str_eq const*& eq_out,
bool& fwd) const {
for (str_eq const& eq : node->str_eqs()) {
SASSERT(eq.m_lhs && eq.m_rhs && !eq.is_trivial());
SASSERT(eq.well_formed() && !eq.is_trivial());
for (unsigned od = 0; od < 2; ++od) {
bool local_fwd = (od == 0);
@ -2506,8 +2500,7 @@ namespace seq {
for (str_eq const& eq : node->str_eqs()) {
if (eq.is_trivial())
continue;
if (!eq.m_lhs || !eq.m_rhs)
continue;
SASSERT(eq.well_formed());
if (eq.m_lhs->is_empty() && eq.m_rhs->first() && eq.m_rhs->first()->is_power()) {
power = eq.m_rhs->first();
dep = eq.m_dep;
@ -2560,10 +2553,9 @@ namespace seq {
// Look for two directional endpoint power tokens with the same base.
for (str_eq const& eq : node->str_eqs()) {
SASSERT(eq.well_formed());
if (eq.is_trivial())
continue;
if (!eq.m_lhs || !eq.m_rhs)
continue;
for (unsigned od = 0; od < 2; ++od) {
bool fwd = (od == 0);
euf::snode* lhead = dir_token(eq.m_lhs, fwd);
@ -2619,12 +2611,9 @@ namespace seq {
bool nielsen_graph::apply_split_power_elim(nielsen_node* node) {
for (str_eq const& eq : node->str_eqs()) {
SASSERT(eq.well_formed());
if (eq.is_trivial())
continue;
// NB: Shuvendu - this test is always false based on how str_eqs are constructed
// it can be an assertion to force the invariant that str_eqs always have both sides non-null.
if (!eq.m_lhs || !eq.m_rhs)
continue;
for (int side = 0; side < 2; ++side) {
euf::snode* pow_side = (side == 0) ? eq.m_lhs : eq.m_rhs;
@ -2760,10 +2749,9 @@ namespace seq {
bool nielsen_graph::apply_gpower_intr(nielsen_node* node) {
for (str_eq const& eq : node->str_eqs()) {
SASSERT(eq.well_formed());
if (eq.is_trivial())
continue;
if (!eq.m_lhs || !eq.m_rhs)
continue;
// Try both directions (ZIPT's ExtendDir(fwd=true/false)).
for (unsigned od = 0; od < 2; ++od) {
@ -3896,7 +3884,7 @@ namespace seq {
// Step 1: Compute LHS (|x|) for each non-eliminating substitution
// using current m_mod_cnt (before bumping).
// Also assert |x|_k >= 0 (mirrors ZIPT's NielsenNode constructor line 172).
svector<std::pair<unsigned, expr*>> lhs_exprs;
vector<std::pair<unsigned, expr_ref>> lhs_exprs;
for (unsigned i = 0; i < substs.size(); ++i) {
auto const& s = substs[i];
if (!s.m_var->is_var())
@ -3904,7 +3892,7 @@ namespace seq {
if (!m_seq.is_seq(s.m_var->get_expr()))
continue;
expr_ref lhs = compute_length_expr(s.m_var);
lhs_exprs.push_back({i, lhs.get()});
lhs_exprs.push_back({i, lhs});
if (s.is_eliminating())
continue;
has_non_elim = true;
@ -3918,12 +3906,10 @@ namespace seq {
// Step 3: Compute RHS (|u|) with bumped mod counts and add |x| = |u|.
for (auto const& p : lhs_exprs) {
unsigned idx = p.first;
expr* lhs_expr = p.second;
for (auto const &[idx, lhs] : lhs_exprs) {
auto const& s = substs[idx];
expr_ref rhs = compute_length_expr(s.m_replacement);
e->add_side_constraint(mk_constraint(m.mk_eq(lhs_expr, rhs), s.m_dep));
e->add_side_constraint(mk_constraint(m.mk_eq(lhs, rhs), s.m_dep));
}
// Step 4: Restore mod counts (temporary bump for computing RHS only).

18
src/smt/seq/seq_nielsen.h
View file

@ -371,10 +371,10 @@ namespace seq {
euf::snode* m_rhs;
dep_tracker m_dep;
str_eq() = default;
str_eq(euf::snode* lhs, euf::snode* rhs, dep_tracker const& dep):
m_lhs(lhs), m_rhs(rhs), m_dep(dep) {}
str_eq(euf::snode* lhs, euf::snode* rhs, dep_tracker const& dep):
m_lhs(lhs), m_rhs(rhs), m_dep(dep) {
SASSERT(well_formed());
}
bool operator==(str_eq const& other) const {
return m_lhs == other.m_lhs && m_rhs == other.m_rhs;
@ -388,6 +388,10 @@ namespace seq {
// check if the constraint contains a given variable
bool contains_var(euf::snode* var) const;
bool well_formed() const {
return !!m_lhs && !!m_rhs;
}
};
struct eq_pp {
@ -407,7 +411,7 @@ namespace seq {
euf::snode* m_regex;
dep_tracker m_dep;
str_mem(): m_str(nullptr), m_regex(nullptr), m_dep(nullptr) {}
// str_mem(): m_str(nullptr), m_regex(nullptr), m_dep(nullptr) {}
str_mem(euf::snode* str, euf::snode* regex, dep_tracker const& dep):
m_str(str), m_regex(regex), m_dep(dep) {}
@ -425,6 +429,10 @@ namespace seq {
// check if the constraint contains a given variable
bool contains_var(euf::snode* var) const;
bool well_formed() const {
return !!m_str && !!m_regex;
}
};
struct mem_pp {

54
src/smt/theory_nseq.cpp
View file

@ -226,14 +226,33 @@ namespace smt {
void theory_nseq::new_eq_eh(theory_var v1, theory_var v2) {
try {
expr* e1 = get_enode(v1)->get_expr();
expr* e2 = get_enode(v2)->get_expr();
auto n1 = get_enode(v1);
auto n2 = get_enode(v2);
auto e1 = n1->get_expr();
auto e2 = n2->get_expr();
TRACE(seq, tout << mk_pp(e1, m) << " == " << mk_pp(e2, m) << "\n");
if (m_seq.is_re(e1)) {
seq_rewriter rw(m);
expr_ref s(m), r(m);
r = m_seq.re.mk_union(m_seq.re.mk_diff(e1, e2), m_seq.re.mk_diff(e2, e1));
switch (rw.some_seq_in_re(r, s)) {
case l_false:
// regexes are equivalent: nothing to do
return;
case l_true: {
// regexes are disjoint: conflict
enode_pair_vector eqs;
literal_vector lits;
eqs.push_back({n1, n2});
set_conflict(eqs, lits);
return;
}
default: break;
}
push_unhandled_pred();
return;
}
if (!m_seq.is_seq(e1) || !m_seq.is_seq(e2))
if (!m_seq.is_seq(e1))
return;
euf::snode* s1 = get_snode(e1);
euf::snode* s2 = get_snode(e2);
@ -252,12 +271,31 @@ namespace smt {
}
void theory_nseq::new_diseq_eh(theory_var v1, theory_var v2) {
expr* e1 = get_enode(v1)->get_expr();
expr* e2 = get_enode(v2)->get_expr();
auto n1 = get_enode(v1);
auto n2 = get_enode(v2);
auto e1 = n1->get_expr();
auto e2 = n2->get_expr();
TRACE(seq, tout << mk_pp(e1, m) << " != " << mk_pp(e2, m) << "\n");
if (m_seq.is_re(e1))
// regex disequality: nseq cannot verify language non-equivalence
push_unhandled_pred();
if (m_seq.is_re(e1)) {
seq_rewriter rw(m);
expr_ref s(m), r(m);
r = m_seq.re.mk_union(m_seq.re.mk_diff(e1, e2), m_seq.re.mk_diff(e2, e1));
switch (rw.some_seq_in_re(r, s)) {
case l_false: {
auto lit = mk_eq(e1, e2, false);
literal_vector lits;
lits.push_back(lit);
ctx.mk_th_axiom(get_id(), lits.size(), lits.data());
break;
}
case l_true:
// the regexes are different
break;
case l_undef:
push_unhandled_pred();
break;
}
}
else if (m_seq.is_seq(e1) && !m_no_diseq_set.contains(e1) && !m_no_diseq_set.contains(e2))
m_axioms.diseq_axiom(e1, e2);
else