Choose challenge
Challenge goal
There remain 0 machines with 5 states to decide!! 🥳
We have reached our goal of proving "BB(5) = 47,176,870":
Here's what's next:
We have reached our goal of proving "BB(5) = 47,176,870":
- See the formal Coq proof
- See the official announcement
- See the human-readable paper presenting the BB(5) proof
Here's what's next:
Visualization:
Change machine:
Random machine from the seed database
More options
From id in the seed database:
From standard format:
Deciders
Deciders
are programs that automatically decide whether machines halt or not.
Here are the currently applied deciders:
Here are the currently applied deciders:
Zoology
This zoology is collaborative.
1. Cyclers
e.g:
#279,081 #4,231,819 #4,239,083
2. Translated cyclers
e.g:
#59,645,887 #15,167,997 #59,090,563 #63,687,188
3. Bouncers
e.g:
#80,747,967 #88,427,177 #5,228,688 #5,608,043
4. Exponential counters
e.g:
#11,004,366 #10,936,909 #3,840,180
5. Bells
e.g:
#8,527,536 #73,261,028 #63,938,734
Not classified yet:
e.g:
#4,446,642 #7,410,754 #43,374,927
Highlighted machines
Interesting machines:
· "inverted counter" [bbchallenge, 2023]
· "helix" [bbchallenge, 2023]
· "pointy wide" [bbchallenge, 2023]
· "chaotic" [Marxen & Buntrock, 1990]
· "complex counter" [Marxen & Buntrock, 1990]
· Machine #7,410,754
· Machine #2,977,651
· Machine #9,005,190
· Machine #43,374,927
· Machine #14,263,231
· Machine #36,909,813
BB champions and other halting machines:
· 2,133,492-halter [bbchallenge, 2021]
· 23,554,764-halter [bbchallenge, 2021]
· BB(5): 47,176,870-halter [Marxen & Buntrock, 1990]
· BB(6): -halter [mxdys, 2025]
Some Skelet's machines:
· Skelet's machine 1 ≈ Machine #68,329,601
· Skelet's machine 17 ≈ Machine #1,365,166