BB(4) champion

@thethinkmachine·version 1·CC BY 4.0·added 28 Sept 2026

Brady’s four-state champion: 107 steps and 13 ones, proven optimal in 1983.

The machine as drawn — 5 states, 8 transitions.

Behaviour

The first steps from a blank tape: one row per step, time running down; the outlined cell is the head.

Halts from a blank tape after 107 steps, leaving 13 non-blank cells.

Standard format1RB1LB_1LA0LC_1RZ1LD_1RD0RAView on bbchallenge.org ↗

Standard format: 1RB1LB_1LA0LC_1RZ1LD_1RD0RA