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Fix nlsat projection bug: ensure polynomials with assumptions are also projected

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When polynomials are added as assumptions (via add_assumption or ensure_sign),
they must also be added to the projection set (m_todo) to ensure proper cell
construction. Previously, assumptions were added without corresponding projection,
leading to unsound lemmas.

Fixes:
1. In normalize(): collect lower-stage polynomials in m_lower_stage_polys and
   add them to m_ps in main() before projection.
2. In ensure_sign(): call insert_fresh_factors_in_todo(p) after adding assumption.
3. In project_cdcac(): when levelwise fails, use flet to set m_add_all_coeffs=true
   for the fallback projection.
This commit is contained in:
Lev Nachmanson 2026-01-24 07:03:14 -10:00
parent a8b8e10d20
commit c4bc251aef
1 changed files with 32 additions and 1 deletions
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33
src/nlsat/nlsat_explain.cpp
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@ -131,6 +131,9 @@ namespace nlsat {
// temporary fields for preprocessing core
scoped_literal_vector m_core1;
scoped_literal_vector m_core2;
// Lower-stage polynomials encountered during normalization that need to be projected
polynomial_ref_vector m_lower_stage_polys;
// temporary fields for storing the result
scoped_literal_vector * m_result = nullptr;
@ -156,6 +159,7 @@ namespace nlsat {
m_todo(u, canonicalize),
m_core1(s),
m_core2(s),
m_lower_stage_polys(m_pm),
m_evaluator(ev) {
m_simplify_cores = false;
m_full_dimensional = false;
@ -516,6 +520,8 @@ namespace nlsat {
SASSERT(max_var(p) != null_var);
SASSERT(max_var(p) < max);
// factor p is a lower stage polynomial, so we should add assumption to justify p being eliminated
// Also collect it for projection to ensure proper cell construction
m_lower_stage_polys.push_back(p);
if (s == 0)
add_assumption(atom::EQ, p); // add assumption p = 0
else if (a->is_even(i))
@ -971,6 +977,8 @@ namespace nlsat {
if (!is_const(p)) {
TRACE(nlsat_explain, tout << p << "\n";);
add_assumption(s == 0 ? atom::EQ : (s < 0 ? atom::LT : atom::GT), p);
// Also add p to the projection to ensure proper cell construction
insert_fresh_factors_in_todo(p);
}
return s;
}
@ -1110,7 +1118,7 @@ namespace nlsat {
if (lws.failed())
return false;
TRACE(lws, for (unsigned i = 0; i < cell.size(); i++)
TRACE(lws, for (unsigned i = 0; i < cell.size(); i++)
display(tout << "I[" << i << "]:", m_solver, cell[i]) << "\n";);
// Enumerate all intervals in the computed cell and add literals for each non-trivial interval.
// Non-trivial = section, or sector with at least one finite bound (ignore (-oo,+oo)).
@ -1154,12 +1162,18 @@ namespace nlsat {
for (auto p: m_todo.m_set)
ps.push_back(p);
bool use_all_coeffs = false;
if (m_solver.apply_levelwise()) {
bool levelwise_ok = levelwise_single_cell(ps, max_x, m_cache);
m_solver.record_levelwise_result(levelwise_ok);
if (levelwise_ok)
return;
// Levelwise failed, use add_all_coeffs mode for fallback projection
use_all_coeffs = true;
}
// Set m_add_all_coeffs for the rest of the projection, restore on function exit
flet<bool> _set_all_coeffs(m_add_all_coeffs, use_all_coeffs || m_add_all_coeffs);
var x = m_todo.extract_max_polys(ps);
polynomial_ref_vector samples(m_pm);
if (x < max_x)
@ -1190,6 +1204,7 @@ namespace nlsat {
x = m_todo.extract_max_polys(ps);
cac_add_cell_lits(ps, x, samples);
}
}
void project(polynomial_ref_vector & ps, var max_x) {
@ -1593,8 +1608,19 @@ namespace nlsat {
return;
}
collect_polys(num, ls, m_ps);
// Add lower-stage polynomials collected during normalization
// These polynomials had assumptions added but need to be projected as well
for (unsigned i = 0; i < m_lower_stage_polys.size(); i++) {
m_ps.push_back(m_lower_stage_polys.get(i));
}
var max_x = max_var(m_ps);
TRACE(nlsat_explain, tout << "polynomials in the conflict:\n"; display(tout, m_solver, m_ps); tout << "\n";);
// Note: levelwise is now called in process2() before normalize()
// to ensure it receives the original polynomials
elim_vanishing(m_ps);
TRACE(nlsat_explain, tout << "after elim_vanishing m_ps:\n"; display(tout, m_solver, m_ps); tout << "\n";);
project(m_ps, max_x);
@ -1602,6 +1628,11 @@ namespace nlsat {
}
void process2(unsigned num, literal const * ls) {
// Reset lower-stage polynomials collection
m_lower_stage_polys.reset();
// Try levelwise with ORIGINAL polynomials BEFORE any normalization
if (m_simplify_cores) {
TRACE(nlsat_explain, tout << "m_simplify_cores is true\n";);
m_core2.reset();