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add flag to control non-linear substitutions: smt.solve_eqs.linear is by default false, setting it to true restricts solutions to substitutions to only use linear terms. This can have an effect on cross-multiplication of nested substitutions

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2026-04-12 09:41:46 -07:00
parent 1544462f47
commit 1566d3cc41
3 changed files with 17 additions and 1 deletions
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15
src/ast/simplifiers/solve_eqs.cpp
View file

@ -121,7 +121,10 @@ namespace euf {
continue;
if (!m_config.m_enable_non_ground && has_quantifiers(t))
continue;
continue;
if (!m_config.m_enable_non_linear && !is_linear(t))
continue;
bool is_safe = true;
unsigned todo_sz = todo.size();
@ -313,6 +316,15 @@ namespace euf {
return num <= m_config.m_max_occs;
}
bool solve_eqs::is_linear(expr* t) const {
unsigned num_values = 0;
if (!is_app(t))
return false;
for (auto arg : *to_app(t))
num_values += m.is_value(arg) ? 1 : 0;
return num_values <= 1;
}
void solve_eqs::save_subst(vector<dependent_expr> const& old_fmls) {
if (!m_subst->empty())
m_fmls.model_trail().push(m_subst.detach(), old_fmls, false);
@ -342,6 +354,7 @@ namespace euf {
smt_params_helper sp(p);
m_config.m_enabled = sp.solve_eqs();
m_config.m_enable_non_ground = sp.solve_eqs_non_ground();
m_config.m_enable_non_linear = !sp.solve_eqs_linear();
}
void solve_eqs::collect_param_descrs(param_descrs& r) {

2
src/ast/simplifiers/solve_eqs.h
View file

@ -43,6 +43,7 @@ namespace euf {
unsigned m_max_occs = UINT_MAX;
bool m_enabled = true;
bool m_enable_non_ground = true;
bool m_enable_non_linear = true;
};
stats m_stats;
@ -74,6 +75,7 @@ namespace euf {
void collect_num_occs(expr * t, expr_fast_mark1 & visited);
void collect_num_occs();
bool check_occs(expr* t) const;
bool is_linear(expr *t) const;
public:

1
src/params/smt_params_helper.pyg
View file

@ -21,6 +21,7 @@ def_module_params(module_name='smt',
('elim_unconstrained', BOOL, True, 'pre-processing: eliminate unconstrained subterms'),
('solve_eqs', BOOL, True, 'pre-processing: solve equalities'),
('solve_eqs.non_ground', BOOL, True, 'pre-processing: solve equalities. Allow eliminating variables by non-ground solutions which can break behavior for model evaluation.'),
('solve_eqs.linear', BOOL, False, 'allow only linear substitutions where a variable is replaced by a term having at most one non-constant argument'),
('propagate_values', BOOL, True, 'pre-processing: propagate values'),
('bound_simplifier', BOOL, True, 'apply bounds simplification during pre-processing'),
('pull_nested_quantifiers', BOOL, False, 'pre-processing: pull nested quantifiers'),