1RB1LF_1LB1LC_1RD0LE_---0RB_0RC0LA_1RC0RF
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1RB1LF_1LB1LC_1RD0LE_---0RB_0RC0LA_1RC0RF (bbch) is a non-halting chaotic-looking BB(6) TM. It's suspected to be a translated cycler with high period and very hard to accelerate, because many other similar looking TMs become translated cyclers in 2e10 steps.
The machine is confirmed not to become a translated cycler up to 2e12 steps.
Analysis by mxdys
On Aug 27 2025, mxdys gave a Rocq proof that this TM does not halt: https://github.com/ccz181078/busycoq/blob/256b1916a325cef4d9f904bc61398e1d97b02c9e/verify/CTLv2.v#L1437-L1438