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## Problem Fixes #10133. For `QF_BV` with `parallel.enable=true`, the solver could return `sat` with a model that violates its own assertions. `mk_qfbv_tactic` routes SAT solving to `mk_psat_tactic`, which built the solver via `mk_inc_sat_solver(m, p, false)` (non-incremental). The parallel cube-and-conquer engine **reuses this single solver** across many `check_sat(cube)` calls, but SAT variable/blocked-clause elimination ran because the simplifier's incremental gate was disabled. Elimination model reconstruction is only sound for a single one-shot solve; under repeated cube assumptions it produces models where eliminated Tseitin variables get values contradicting the original clauses. ## Root cause (two coupled defects) 1. **Stale simplifier cache.** `inc_sat_solver`'s constructor called `m_solver.set_incremental()` *after* `updt_params()`. The SAT simplifier caches `m_incremental_mode` from the SAT config *during* `updt_params`, so setting the incremental flag afterwards left a stale non-incremental mode and elimination stayed enabled. (This is why simply passing `incremental_mode=true` had no effect on its own.) 2. **Non-incremental parallel solver.** `mk_psat_tactic` created the reused solver as non-incremental. ## Fix - Move `set_incremental()` **before** `updt_params()` in the `inc_sat_solver` constructor so the simplifier caches the correct mode. - Create the parallel solver with `incremental_mode=true` in `mk_psat_tactic`. ## Validation - Variable elimination on the QF_BV parallel path drops to zero (`sat-elim-bool-vars-res` 21664 -> 0); remaining `elim-clauses/literals` are sound cleaner/subsumption steps. - Consistent with ground truth: on 4.16.0, `sat.elim_vars=false` removed all 7 `failed to verify` errors; this change disables exactly that unsound elimination, scoped to the reused/parallel solver. - A solvable QF_BV instance returns a **valid** model under `parallel.enable=true model_validate=true`. - All 92 unit tests pass (`test-z3 /a`). Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> |
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| .. | ||
| sat_solver | ||
| smt | ||
| tactic | ||
| CMakeLists.txt | ||
| dimacs.cpp | ||
| dimacs.h | ||
| sat_aig_finder.cpp | ||
| sat_aig_finder.h | ||
| sat_allocator.h | ||
| sat_anf_simplifier.cpp | ||
| sat_anf_simplifier.h | ||
| sat_asymm_branch.cpp | ||
| sat_asymm_branch.h | ||
| sat_asymm_branch_params.pyg | ||
| sat_bcd.cpp | ||
| sat_bcd.h | ||
| sat_big.cpp | ||
| sat_big.h | ||
| sat_clause.cpp | ||
| sat_clause.h | ||
| sat_clause_set.cpp | ||
| sat_clause_set.h | ||
| sat_clause_use_list.cpp | ||
| sat_clause_use_list.h | ||
| sat_cleaner.cpp | ||
| sat_cleaner.h | ||
| sat_config.cpp | ||
| sat_config.h | ||
| sat_ddfw_wrapper.cpp | ||
| sat_ddfw_wrapper.h | ||
| sat_drat.cpp | ||
| sat_drat.h | ||
| sat_elim_eqs.cpp | ||
| sat_elim_eqs.h | ||
| sat_extension.h | ||
| sat_gc.cpp | ||
| sat_integrity_checker.cpp | ||
| sat_integrity_checker.h | ||
| sat_justification.h | ||
| sat_local_search.cpp | ||
| sat_local_search.h | ||
| sat_lookahead.cpp | ||
| sat_lookahead.h | ||
| sat_model_converter.cpp | ||
| sat_model_converter.h | ||
| sat_mus.cpp | ||
| sat_mus.h | ||
| sat_npn3_finder.cpp | ||
| sat_npn3_finder.h | ||
| sat_parallel.cpp | ||
| sat_parallel.h | ||
| sat_prob.cpp | ||
| sat_prob.h | ||
| sat_probing.cpp | ||
| sat_probing.h | ||
| sat_proof_trim.cpp | ||
| sat_proof_trim.h | ||
| sat_scc.cpp | ||
| sat_scc.h | ||
| sat_scc_params.pyg | ||
| sat_simplifier.cpp | ||
| sat_simplifier.h | ||
| sat_simplifier_params.pyg | ||
| sat_solver.cpp | ||
| sat_solver.h | ||
| sat_solver_core.h | ||
| sat_types.h | ||
| sat_watched.cpp | ||
| sat_watched.h | ||
| sat_xor_finder.cpp | ||
| sat_xor_finder.h | ||