BB(6) hunt
Machines / P-64

1RB0LC_0RC0RB_1LD0RE_0LE0LF_1LA0LB_1RA---

P-64SkippedSkelet 1-like Class 1bbchallenge ↗Explorer

Where it stands

Skipped

Twin port refuted. In TM1's digit representation D1 fires in exactly 3 RInc cases; there 64f writes the word 0011001 where TM1 writes 0000101 (2 steps fewer).

Read the full status

The exact 64f map RIncF (44 obligations, symbolically derived) differs from RInc only there plus a Tp3 return. A direct re-read heals the defect (+12 steps), but a neighbour read by D0011 0 does not: TM1 makes D0011_000101 -> ... -> D0011101 (a new exit), 64f makes D0011_011001 -> ... -> D00101001 (carries on). Exits 1-6 coincide (Inc 109 ... 528,713); the orbits split at Inc 529,337 (374,704 cells differ); TM1's exit 7 (Inc 529,462) has no 64f counterpart; TM1 reaches upstream's S' at Inc 1,333,817, 64f does not (11 exits by Inc 1e8, counter-like regime, no inr). Critical Inc steps re-run on the list strings.

Observe
Deepen
Informal proof
Rocq
space-time diagram, first 10,000 steps from blank
The first 10,000 steps from a blank tape. Time runs down; white is 1.
About this picture

The standard picture (bbchallenge.org's Default view): each row is the whole tape at one step, time runs downward, and the head's path draws the pattern.

bbchallenge-defaultStart blankRows steps 0 → 10,000, top to bottomWindow cells −200..199, left to rightColors 1 0 or unvisited

Overview

In one sentence

flip(64) = 1LB0RC_0LC0LB_1RD0LE_0RE0RF_1RA0RB_1LA--- = TM1 with D1 0RF (vs 1RF) and F0 1LA (vs 1RA); same states, same start A; init to x0 identical (1699 steps, D1-free) (status.json relation)

Status
Skippedtwin port refuted · updated 2026-10-14Parked · Twin port refuted.
idle since Oct 14 16:13 (45 h ago) · status.json 2026-10-14
Class
Skelet 1-like Class 1
On the list
line 59 of BB6_holdouts_663.txt · historical 740 line 64
eqv ×1sim 1e15
Your calls on file 1
next
No port. Back to the K42 pool (strategy direction 2). Asset for the K42 atlas: RIncF, an exact case-by-case accelerator in Sk1like_TC_v1's representation (Coq: copy RD/RC/RInc/Inc, change 3 exit branches, add Tp3 and its 2 callers; untested in coqc). A kill needs an invariant on RIncF's counter regime.

Mechanism

No observation yet: no observe.json here. See notes.md.

Proof & checks

No proof work yet.

Files

machines/<tm>/: 6 entries · raw notes, status, scripts, images

namesizechanged
notes.md ↓7.7 KB2026-10-14 16:13
status.json ↓2.1 KB2026-10-14 16:13
logs/2 items2026-10-14 16:13
check_twin.py ↓17 KB2026-10-14 16:11
orbit_long.py ↓1.1 KB2026-10-14 16:13
symexec.py ↓27 KB2026-10-14 16:08
status.json in full
{
 "tm": "1RB0LC_0RC0RB_1LD0RE_0LE0LF_1LA0LB_1RA---",
 "label": "P-64",
 "status": "SKIPPED",
 "stage": "twin_port_refuted",
 "updated": "2026-10-14",
 "confidence": "high",
 "holdout_line_740": 64,
 "class": "Skelet 1-like Class 1 (K42 core)",
 "parent": "Sk1like_TC_v1.v Module TM1 (1LB0RC_0LC0LB_1RD0LE_0RE1RF_1RA0RB_1RA---), nonhalt",
 "relation": "flip(64) = 1LB0RC_0LC0LB_1RD0LE_0RE0RF_1RA0RB_1LA--- = TM1 with D1 0RF (vs 1RF) and F0 1LA (vs 1RA); same states, same start A; init to x0 identical (1699 steps, D1-free)",
 "reason": "Twin port refuted. In TM1's digit representation D1 fires in exactly 3 RInc cases; there 64f writes the word 0011001 where TM1 writes 0000101 (2 steps fewer). The exact 64f map RIncF (44 obligations, symbolically derived) differs from RInc only there plus a Tp3 return. A direct re-read heals the defect (+12 steps), but a neighbour read by D0011 0 does not: TM1 makes D0011_000101 -> ... -> D0011101 (a new exit), 64f makes D0011_011001 -> ... -> D00101001 (carries on). Exits 1-6 coincide (Inc 109 ... 528,713); the orbits split at Inc 529,337 (374,704 cells differ); TM1's exit 7 (Inc 529,462) has no 64f counterpart; TM1 reaches upstream's S' at Inc 1,333,817, 64f does not (11 exits by Inc 1e8, counter-like regime, no inr). Critical Inc steps re-run on the list strings.",
 "checks": {
  "check_twin": "check_twin.py SUMMARY PASS (17 checks, ~20 s; logs/check_twin_full.log)",
  "orbit_1e8": "logs/rincf_orbit_1e8.log (orbit_long.py twin 1e8)"
 },
 "siblings": [
  "1RB0LC_0RC0RF_1RD0RE_1LE0RA_0LA0LE_1LD---"
 ],
 "sibling_note": "740 line 124 (P-124) is the same table started in TM1-state C (TM3's renaming); against TM3 it splits at Inc 529,352 the same way (check_twin.py T). Line 305 is the third start of this table per reports/strategy/equivalence-candidates.tsv.",
 "next": "No port. Back to the K42 pool (strategy direction 2). Asset for the K42 atlas: RIncF, an exact case-by-case accelerator in Sk1like_TC_v1's representation (Coq: copy RD/RC/RInc/Inc, change 3 exit branches, add Tp3 and its 2 callers; untested in coqc). A kill needs an invariant on RIncF's counter regime."
}