``` a,b=8,0 while b!=-1: b+=2-a%2*3 a+=a>>1 ```
Showing that these halt or not are long-standing open problems, so knowing upper bounds BB(6) would immediately solve them (modulo a lot of compute time).
A number, that if known, would allow us to derive the truth value of any statements from it.
The proof that BB(6) is relevant is that you can encode it in a 6 instruction program, which is what the link does.
gliptic•6h ago
cubefox•5h ago
https://news.ycombinator.com/item?id=44406171