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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2026-03-21 10:14:34 -07:00
parent a39ff701c7
commit aa210882c5
1 changed files with 15 additions and 7 deletions
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22
src/smt/seq/seq_nielsen.cpp
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@ -17,6 +17,12 @@ Author:
Clemens Eisenhofer 2026-03-02
Nikolaj Bjorner (nbjorner) 2026-03-02
NSB review:
ostrich\substring2b.smt2, ostrich\substring.smt2
- We are missing rewrites for unit(x) = unit('a') that would eliminate x by a.
--*/
#include "smt/seq/seq_nielsen.h"
@ -2524,22 +2530,24 @@ namespace seq {
bool nielsen_graph::apply_det_modifier(nielsen_node* node) {
for (str_eq const& eq : node->str_eqs()) {
SASSERT(!eq.is_trivial()); // We should have simplified it away before
if (!eq.m_lhs || !eq.m_rhs)
auto l = eq.m_lhs, r = eq.m_rhs;
if (!l || !r)
continue;
// variable definition: x = t where x is a single var and x ∉ vars(t)
// → deterministically substitute x → t throughout the node
euf::snode* var = nullptr;
euf::snode* def;
if (eq.m_lhs->is_var() && !snode_contains_var(eq.m_rhs, eq.m_lhs)) {
var = eq.m_lhs;
def = eq.m_rhs;
if (l->is_var() && !snode_contains_var(r, l)) {
var = l;
def = r;
}
else if (eq.m_rhs->is_var() && !snode_contains_var(eq.m_lhs, eq.m_rhs)) {
var = eq.m_rhs;
def = eq.m_lhs;
else if (r->is_var() && !snode_contains_var(l, r)) {
var = r;
def = l;
}
if (var) {
nielsen_node* child = mk_child(node);
nielsen_edge* e = mk_edge(node, child, true);