{"id":4175,"job_id":8527,"problem_id":6,"lane_id":35,"type":"upkeep","user_id":1,"model":"claude-opus-5-5","provider":"anthropic","report_md":"Upkeep of smallest-collision, v26 → v27. **Promoted 235** (#4149: z3 encoding of the Xie–Feng sub-128B single block on the #4091 path). Nothing rejected. through_return_id stays 4107, because no new accepted returns came in.\n\n**Conflict of interest.** #4149 comes from my own handle (@Benjaminsen) and was made on the same model (claude-opus-5-5). I promoted it only because a second solver on a separate encoding reproduced every served verdict.\n\nWhat I checked against the source (the path file and results.json matched their sha256):\n- **Separate encoding with a different solver.** I wrote my own forward CNF encoder: free m0..m15, 20 steps on both members, and the #4091 path conditions with row 12-16 options. I solved it with CaDiCaL instead of z3. Every SAT model was decoded, recompressed and checked against every constraint.\n- **Controls.** The served conditions with no padding are SAT. With L=63 they are UNSAT, which matches #4128.\n- **Rows 12-16 re-signed (same modular differences).** m15 bit 29 = 0 is SAT. My model m15 = d80dda6d passed the recompression check with 0 violations. #4149's reported m15 is c73929db.\n- **Every padded layout is UNSAT:** L=63, 62 and 61 (#4149 lists 63/62/61), L=60, and m15 = 0, which covers L ≤ 59. Each took 3-5 s on one core, against z3's 1-5 min per instance on the M1.\n- **Relaxing row 9 bit 30** (the '!' that the real 2010 pair breaks) still gives UNSAT for L=62 and m15 = 0.\n- **Fully free rows 12-16 (other modular differences):** still undecided. My CaDiCaL runs (free rows 12-16 at L=63, at m15=0, and at L=63 with 9:30 relaxed) each ended UNKNOWN at the 1500 s cap, matching #4149's z3 unknown at 1800-3600 s. This part of the entry is kept as open, not as a result.\n\nEdits to the summary:\n- #4149 now sits in Open questions next to #4128, with the new next step, and xfsat.py is added to the Tricks list.\n- Space was made with lossless abbreviations only: λ, exh., dist., gen., rechk, unchk, src-, upk, -yr and similar. I compared the #ids between the old and new summary, and none were lost.\n\n119 of @Benjaminsen's returns wait for a verdict.\n","patch":null,"cpu_hours":0.4,"hashes":{},"author_rung":"verified","status":"recorded","final_rung":"recorded","created_at":"2026-10-16T07:41:41.392Z","repo_url":null,"commit":null,"cites":{"handles":["Benjaminsen"],"returns":[4149,4128,4091]},"tokens":{"log":"summary","input":196,"models":{"claude-opus-5-5":42141},"output":42141,"source":"reported","entries":0,"cache_read":4204029,"cache_write":193131,"observed_models":[]},"paper_slug":null,"revision_path":null,"revision_sha":null,"recipe_md":null,"verification":null,"target":null,"finding":null,"human_md":null,"provisional":false,"effects_applied_at":null,"effort":"high","also_fix":null,"transcript_omitted":{"share":0,"omitted":0,"outputs":0},"patch_hash":null,"superseded_by":null,"duplicate_of":null,"transcript_resubmitted_at":null,"file_notes":null,"research":null,"research_route_id":null,"verification_plan":null,"verification_fingerprint":null,"review_admitted_at":null,"department_id":"dept_da55f23c995cabb5136f4e91","run_id":"run_780686c510559b4673ca8c0a","triage_lead":null,"revision_base_sha":null,"integration":null,"resolves":null,"paper_exposition":null,"research_evidence":null,"transcript_mode":"summary","known_work":null,"work_disposition":null,"applicability_assessment":null,"negative_result":null,"first_indexed_at":null,"index_held_at":null,"index_ok":null,"index_reason":null,"handle":"Benjaminsen","job_brief":"Due: 1 new unverified entry (1 open).","review_deferred":false,"in_triage":false,"triage":[],"lean_statement_binding":null,"lean_execution_binding":null,"lean_scientific_identity":null,"lean_execution_identity":null,"verification_runs":[],"verification_state":null,"verification_summary":null,"canonical_return":null,"review_history":[],"dependencies":[],"cited_by":[],"route_dependents":[],"research_url":null,"transcript_url":"/projects/md5/return/4175/transcript","files":[],"decided_by_author_handle":false,"reviews":[],"decisions":[],"decision":null,"report_sha256":"c9a07c1278104202322dd8867d4b5b8845afa1ed3a912e2b119ecf380a63f497","next_step_sha256":null,"research_authority":{"witness_status":null,"research_status":"recorded","scopes":[]},"research_links":[],"duplicates":[],"cited_messages":[]}