BB(6) hunt
Machines / #29

1RB0RA_1LC0LF_1LE0LD_1LB---_1RA1LB_0LB0RC

#29Claimed elsewhereBell eats counterbbchallenge ↗Explorer

Upstream result

Claimed elsewhere

The blank-start machine never halts: BECv10.v.TM29 ↗. Recorded commit time: 2026-10-13T13:42:06Z. First public push time is not established.

Absent from the current 663 holdout list. Earlier local observations remain below.

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

BECv1 tm108 twin (E1): 3-cell binary counter, unary, marker; rounds ruled (99.7%), the grid-shifting eat is open

Upstream
The blank-start machine never halts: BECv10.v.TM29 ↗. Recorded commit time: 2026-10-13T13:42:06Z. First public push time is not established.
Status
Externally Solvedtight · updated 2026-10-11Not blocking · Stuck at the tight stage. Answer Q1–Q3 whenever; a “no” redirects the work.
idle since Oct 11 08:55 · status.json 2026-10-11
Class
Bell eats counterours: Bell eats counter (sheet) · ours adds: BECv1 tm108 twin (E1) with 3-cell counter digits and a grid-shifting eat · med confidence
On the list
not on BB6_holdouts_663.txt (line 191 of the previous list) · historical 740 line 191
#29eqv ×1sim 1e15
Your calls on file 6
priority call (answered)
With #29's generic size lemma proved and only the leading-spacer recovery left (true on all 265,642 test words, unproved), fund one last ~2 h stage on it with a hard stop, or park #29 as STUCK now?
funded
option: tight · date: 2026-10-11
2026-10-10 · deepen
#29's rounds, overflow and marker are ruled (99.7% of K-transitions to 1e10), but the grid-shifting eat is not. Spend one ~2 h deepen stage ruling the eat, or park #29 as STUCK? (Dennis: go with all recommendations (2026-10-10))
2026-10-10 · recovery
With every #29 round ruled and the size bound proven by test except in rare leading-spacer epochs (where a surviving t has always recovered), fund one ~2 h recovery stage, or park #29 as STUCK? (auto-applied: Claude's recommendation, under Dennis's standing instruction 'do your recommendations and continuously orchestrate' (2026-10-10, while he was away). Override any time.)
2026-10-10 · size_invariant
With #29's eat ruled and safe for every t-free counter, fund one ~2 h stage on the last size invariant (eat-made t units clear before the next eat), or park #29 as STUCK at it? (auto-applied: Claude's recommendation, under Dennis's standing instruction 'do your recommendations and continuously orchestrate' (2026-10-10, while he was at lunch). Override any time.)
2026-10-11 · tight
With #29's generic size lemma proved and only the leading-spacer recovery left (true on all 265,642 test words, unproved), fund one last ~2 h stage on it with a hard stop, or park #29 as STUCK now? (Dennis: go with recommendations (2026-10-11))

Mechanism

How it works: 3 notes
  • Tape: counter W of 3-cell units (0 = 000, 1 = 100, spacer 010; MSB left), unary (010)^b, marker 00, then (101)^c. Only E1 differs from tm108: B carries, so digits are 3-cell units.
  • Each round the marker steps one unit left (b-1, c+1) and W += 1 (B carries over 100 and spacers, turns at 000); an overflow adds a 3-cell digit at the left end.
  • At b = 0 the marker eats W: the 3-cell grid shifts by one cell (1-digits -> spacers, spacers -> 001), c becomes the new unary, the marker is reborn at the right, then mini-eats re-align W. N ~ (4t)^(1/3); no halt to 1e10.

Figures for Checkpoint A

Fig 1 · bbchallenge default view, first 10,000 stepsviewer ↗

The site's own view. Each zigzag is one round between the counter (left turns) and the marker (right turns).

bbchallenge default view, first 10,000 steps
bbchallenge-defaultStart blankRows every step 0..9,999Window cells -200..199, 1 px = 1 cellColors 1 0 or unvisited head (last move right/left)
Rows: squeezed into 500 px by the site's bilinear filter: px row y blends steps 20y+9 and 20y+10, so effectively one sample every 20 steps
Fig 2 · One eat, step by stepQ1

One row per step. Follow the right turning point leftwards until it meets the left turns, then the run right.

One eat, step by step
bbchallenge-defaultStart mid-run: step 19,500Rows every step 19,500..20,399Window cells -110..39, 1 px = 0.5 cellsColors 1 0 or unvisited head (last move right/left)
Start: blank run; config in img/eat_start_19500.txt · Rows: 900 rows, each 2 px tall · Window: (each cell 2x2 px); cell numbers are those of the blank run (start cell = 0)
Fig 3 · Blaze, 1 billion steps

Overall shape only. Compare the moving left edge with the nearly fixed right edge; faint horizontal bands are epochs.

Blaze, 1 billion steps
bbchallenge-blazeStart blankRows Blaze time blocks of 1,048,576 stepsWindow cells -4288..527, 1 px = 6 cellsColors 0 1 1 only part of the time (or in part of the cells) of that pixel's block
Rows: (each averaged), 954 blocks to step 1e9, stretched to 500 px (1 px = about 2 million steps) · Window: Blaze image: 1 column per 4 cells, 1,204 columns stretched to 800 px · Colors: no head
More figures (1)Fig 4: Left records, left edge pinned
Fig 4 · Left records, left edge pinnedviewer ↗

One row per new leftmost cell; an overflow makes three. The pinned edge shows the counter word between epochs.

Left records, left edge pinned
bbchallenge-defaultStart blankRows left records onlyWindow cells 0..149, 1 px = 0.5 cellsColors 1 0 or unvisited head (last move right/left)
Rows: the start, then one row per new leftmost cell (839 rows to step 10,000,000; 3 rows per counter overflow; not evenly spaced in time) · Window: (each cell 2x2 px); counted from each row's leftmost visited cell (frame = left), the rest of the tape is cut off
Rules (11/12 validated)exact tape rewrites the proof will formalize, each re-checked by simulation
rulefrom ⟶ tocasesstepschecked
R1 A over spacer (= BECv1 HR1)
l A> (101)n r
⟶ l (010)n A> r
—7n✓60/60
R2 A over carried digit
l A> 111 r
⟶ l 000 A> r
—3✓60/60
R3 B over spacer (= HR3)
l (010)n <B r
⟶ l <B (101)n r
—3n✓60/60
R4 carry over digit 1
l 100 <B r
⟶ l <B 111 r
E1 = 1LB hands the carry back to B (tm108: E keeps carrying)3✓60/60
R5 turn at digit 0
l 000 <B r
⟶ l 100 A> r
—5✓60/60
R6 overflow at the left end
0∞ <B r
⟶ 0∞ 100 A> r
new MSB digit, 3 cells5✓60/60
R7 marker step (= HR2)
l A> 101 00 101 r
⟶ l <B 00 101 101 r
—13✓60/60
R8 marker birth (= HE2)
l 010 A> 0∞
⟶ l <B 00 101 0∞
—6✓60/60
ROUND: one counter increment
0∞ W (010)b+1 A> 101 00 (101)c 0∞
⟶ 0∞ inc(W) (010)b A> 101 00 (101)c+1 0∞
W over {010,000,100}, ends in a digit; W = U 000 V with V in {010,100}* (s, o = counts in V): inc(W) = U 100 V' (V' = V with 100 -> 000); no 000 in W: inc(W) = 100 V'. Holds for 870,221 of 872,741 K-to-K transitions from blank to 1e10 (0 mismatches)10b+21+10s+6o✓372/372
OVERFLOW: one counter period, left record to left record
0∞ <B W (101)b 00 (101)c 0∞
⟶ 0∞ <B 111 W (101)b-2^D 00 (101)c+2^D 0∞
W over {111,101} (all digits carried), D = number of 111 units, b > 2^D. From blank: 2,382 of 2,382 in-epoch left-record pairs to 1e10; c = 2^D-1 at 2,911 of 2,919 clean left records—✓150/150
EAT shape (b = 0), aligned W: no halt, next K reached
0∞ W A> 101 00 (101)c 0∞ (b = 0)
⟶ 0∞ W' (010)b' A> 101 00 (101)c' (r') 0∞, marker reborn at the right end
Shape check only (no halt, a K-moment follows). W' is W re-read on a grid shifted by one cell (100 -> 010, 000 -> 000, 010 -> 001) plus local changes; exact form not ruled—✓400/400
EAT cascade: exact rule (open)
eat with 001 units (shifted segments) and pseudo-markers
⟶ open
2,186 eat/mini-eat transitions and 334 carries into shifted segments to 1e10 are not covered by any exact rule yet—–untested
Compressed historythe tape as 0∞ <B W (101)b 00 (101)c 0∞ (at each left record; W over d = 111, S = 101) at 36 moments: where the rules are read off
0∞ <B W (101)b 00 (101)c 0∞ (at each left record; W over d = 111, S = 101)
stepW (d = digit, S = spacer; MSB left)D (digits in W)bc
7,904d1291
8,499dd2273
9,572ddd3237
11,241dddd41515
13,034d1351
13,749dd2333
15,062ddd3297
17,211dddd42115
19,592ddddd5531
22,402SddSd3317
24,761dSddSd42315
27,562ddSddSd5731
30,808SSdSdd3347
33,397dSSdSdd42615
100,093,972ddddSSddSdSSdSSSSSSSSSSSSSSSSSSSSSSSd9179511
100,500,756SSddSSSSdSdSSd568431
100,715,701dSSddSSSSdSdSSd665263
101,114,874ddSSddSSSSdSdSSd7588127
101,790,343dddSSddSSSSdSdSSd8460255
102,649,764ddddSSddSSSSdSdSSd9204511
103,084,352SSddSSSSdSSSSSSdSSd568531
103,300,017dSSddSSSSdSSSSSSdSSd665363
103,700,630ddSSddSSSSdSSSSSSdSSd7589127
104,378,979dddSSddSSSSdSSSSSSdSSd8461255
9,822,265,052dSSSdSdSSSdd53,48431
9,823,375,757ddSSSdSdSSSdd63,45263
9,825,566,450dddSSSdSdSSSdd73,388127
9,829,824,959ddddSSSdSdSSSdd83,260255
9,837,850,460dddddSSSdSdSSSdd93,004511
9,851,935,385ddddddSSSdSdSSSdd102,4921,023
9,872,240,918dddddddSSSdSdSSSdd111,4682,047
9,899,736,054SSSdddddSSSdSdSSSdd93,005511
9,913,826,129dSSSdddddSSSdSdSSSdd102,4931,023
9,934,141,962ddSSSdddddSSSdSdSSSdd111,4692,047
9,975,773,479SdSdSSSdddddSSSdSdSSSd102,4951,023
9,996,120,762dSdSdSSSdddddSSSdSdSSSd111,4712,047
W (d = digit, S = spacer; MSB left)last dSdSdSSSdddddSSSdSdSSSd
not plottable
D (digits in W)last 11
1117,9041e10log xstep 7904: D (digits in W) = 1step 8499: D (digits in W) = 2step 9572: D (digits in W) = 3step 11241: D (digits in W) = 4step 13034: D (digits in W) = 1step 13749: D (digits in W) = 2step 15062: D (digits in W) = 3step 17211: D (digits in W) = 4step 19592: D (digits in W) = 5step 22402: D (digits in W) = 3step 24761: D (digits in W) = 4step 27562: D (digits in W) = 5step 30808: D (digits in W) = 3step 33397: D (digits in W) = 4step 100093972: D (digits in W) = 9step 100500756: D (digits in W) = 5step 100715701: D (digits in W) = 6step 101114874: D (digits in W) = 7step 101790343: D (digits in W) = 8step 102649764: D (digits in W) = 9step 103084352: D (digits in W) = 5step 103300017: D (digits in W) = 6step 103700630: D (digits in W) = 7step 104378979: D (digits in W) = 8step 9822265052: D (digits in W) = 5step 9823375757: D (digits in W) = 6step 9825566450: D (digits in W) = 7step 9829824959: D (digits in W) = 8step 9837850460: D (digits in W) = 9step 9851935385: D (digits in W) = 10step 9872240918: D (digits in W) = 11step 9899736054: D (digits in W) = 9step 9913826129: D (digits in W) = 10step 9934141962: D (digits in W) = 11step 9975773479: D (digits in W) = 10step 9996120762: D (digits in W) = 11
blast 1,471
3,48457,9041e10log xstep 7904: b = 29step 8499: b = 27step 9572: b = 23step 11241: b = 15step 13034: b = 35step 13749: b = 33step 15062: b = 29step 17211: b = 21step 19592: b = 5step 22402: b = 31step 24761: b = 23step 27562: b = 7step 30808: b = 34step 33397: b = 26step 100093972: b = 179step 100500756: b = 684step 100715701: b = 652step 101114874: b = 588step 101790343: b = 460step 102649764: b = 204step 103084352: b = 685step 103300017: b = 653step 103700630: b = 589step 104378979: b = 461step 9822265052: b = 3484step 9823375757: b = 3452step 9825566450: b = 3388step 9829824959: b = 3260step 9837850460: b = 3004step 9851935385: b = 2492step 9872240918: b = 1468step 9899736054: b = 3005step 9913826129: b = 2493step 9934141962: b = 1469step 9975773479: b = 2495step 9996120762: b = 1471
clast 2,047
2,04717,9041e10log xstep 7904: c = 1step 8499: c = 3step 9572: c = 7step 11241: c = 15step 13034: c = 1step 13749: c = 3step 15062: c = 7step 17211: c = 15step 19592: c = 31step 22402: c = 7step 24761: c = 15step 27562: c = 31step 30808: c = 7step 33397: c = 15step 100093972: c = 511step 100500756: c = 31step 100715701: c = 63step 101114874: c = 127step 101790343: c = 255step 102649764: c = 511step 103084352: c = 31step 103300017: c = 63step 103700630: c = 127step 104378979: c = 255step 9822265052: c = 31step 9823375757: c = 63step 9825566450: c = 127step 9829824959: c = 255step 9837850460: c = 511step 9851935385: c = 1023step 9872240918: c = 2047step 9899736054: c = 511step 9913826129: c = 1023step 9934141962: c = 2047step 9975773479: c = 1023step 9996120762: c = 2047
Template comparisonBECv1_6x2_solved.v: partly applies · the nearest solved proof, what carries over, and the transitions that differ
01
A1RB0RA
B1LC0LF
C1LE0LD
D1LB---
E1RA1LBtpl 1LE
F0LB0RC

differs from the template

file
BECv1_6x2_solved.v:872
module
—
machine
1RB0RA_1LC0LF_1LE0LD_1LB---_1RA1LE_0LB0RC (1 transition apart)
diff
E1: 1LB here vs 1LE in tm108
note
The right half is identical: tm108's HR1, HR2, HR3 and HE2 (w0 = 101, w0' = 010, w1 = 00) hold here as R1, R7, R3 and R8. The left counter is not: in tm108, E carries over single-cell digits and m0 = 00 separates the counter from the unary. Here B carries (R4), digits are 3-cell units mixed with 010 spacers, and the eat shifts the grid, so solve_BECv1 (and its fixed-width LeftBinaryCounter) cannot apply.
Proof strategy & riskshow the formal proof will go · 3 risks to watch

Not ready for a proof. Next: rule the eat as a transducer on the counter word: the one-cell grid re-read (100 -> 010, 000 -> 000, 010 -> 001), then the mini-eat cascade until W is aligned again. Then look for a regular invariant on such words (BECv7/BECv8 carry-head and two-track transducer proofs are the closest style).

  • ▲The eat cascade is long and context-dependent: random {010,000,100,001} words with no 100-001 pair still halt in about 5% of trials, so the invariant must be finer than unit bigrams.
  • ▲The eat consumes the counter's bit pattern at eat time (about N mod 2^D). If safety depends on those bits, this becomes arithmetic (cryptid protocol).
  • ▲Proof size: likely a BECv7/BECv8-class file (tens of KB), not a one-line certificate.
Stats & provenance1010 steps simulated · 10,628 cells · the status in full · files
simulated
1010 steps
tape
10,628 cells · 6,528 nonzeros
growth
span ~ t^(1/3): unary N ~ (4t)^(1/3) units, span ~ 3N cells (10,628 at 1e10)
status now
Parked by the agreed hard stop of the funded stage 'tight' (2026-10-11): the leading-spacer recovery lemma is not proved. Proved in the stage (informally, on validated unit rules): a closed form TF of when a leading-spacer eat word keeps a t (one bit pattern per layout; exact on all 265,642 words to 13 units and 103,000 long random or constructed words), the exact word it produces (bin(C_0) t^a inc(W)[a:]), that the next eat never reaches the surviving t, and that the first unit to reach the new v = 110 unit is a C run, never the B carry. Open: the head after that C-meets-v event (no unit rule; observed real = shadow plus a head) and a bound on how many eats the head survives (observed 1-3, 0 halts in every test). Not a cryptid: tightness is an explicit congruence on the layout and halting never depends on the bits. No further stages. (status.json, 2026-10-11)
observer's note
Mechanism identified at medium confidence: rounds, overflow, marker step and birth are ruled and validated; the eat (grid shift plus mini-eat cascade, 0.29% of K-transitions to 1e10) is not ruled. Proof work waits for Dennis (CLAUDE.md: med confidence).
files
observe.json · notes.md · status.json

Proof & checks

No proof work yet.

Files

machines/<tm>/: 13 entries · raw notes, status, scripts, images

namesizechanged
notes.md ↓44 KB2026-10-11 08:55
status.json ↓1.3 KB2026-10-11 08:55
observe.json ↓14 KB2026-10-10 10:12
deepen.json ↓14 KB2026-10-11 08:55
data/7 items2026-10-10 15:07
decisions/4 items2026-10-11 08:55
img/11 items2026-10-10 10:09
scripts/6 items2026-10-11 08:21
compress_track_auto.txt ↓4.1 KB2026-10-10 09:35
compress_track_records_1e8.txt ↓4.1 KB2026-10-10 09:35
qsim_summary.jsonl ↓474 B2026-10-10 09:35
sim_1e10.jsonl ↓152 B2026-10-10 09:36
validation.json ↓1.1 KB2026-10-10 10:07
status.json in full
{
 "tm": "1RB0RA_1LC0LF_1LE0LD_1LB---_1RA1LB_0LB0RC",
 "status": "STUCK",
 "stage": "tight",
 "updated": "2026-10-11",
 "reason": "Parked by the agreed hard stop of the funded stage 'tight' (2026-10-11): the leading-spacer recovery lemma is not proved. Proved in the stage (informally, on validated unit rules): a closed form TF of when a leading-spacer eat word keeps a t (one bit pattern per layout; exact on all 265,642 words to 13 units and 103,000 long random or constructed words), the exact word it produces (bin(C_0) t^a inc(W)[a:]), that the next eat never reaches the surviving t, and that the first unit to reach the new v = 110 unit is a C run, never the B carry. Open: the head after that C-meets-v event (no unit rule; observed real = shadow plus a head) and a bound on how many eats the head survives (observed 1-3, 0 halts in every test). Not a cryptid: tightness is an explicit congruence on the layout and halting never depends on the bits. No further stages.",
 "funded": {
  "option": "tight",
  "date": "2026-10-11"
 },
 "confidence": "med",
 "priority_call_answered": "With #29's generic size lemma proved and only the leading-spacer recovery left (true on all 265,642 test words, unproved), fund one last ~2 h stage on it with a hard stop, or park #29 as STUCK now?"
}