Skelet 26
1RB1LD_1RC0RB_1LA1RC_1LE0LA_1LC--- (bbch), called Skelet #26, was one of Skelet's 43 holdouts and one of the last holdouts in BB(5). It is a Shift overflow counter and has an individual proof of non-halting in Coq-BB5.[1] It is equivalent to Skelet 15.
Skelet 26 was proven to be non-halting in January 2024 by int-y1 and meithecatte.[2]
Skelet 15
1RB---_1RC1LB_1LD1RE_1LB0LD_1RA0RC (bbch), also called Skelet #15 is equivalent to Skelet 26. It was proven to be non-halting together with Skelet 26 in January 2024 by int-y1 and meithecatte.[2]