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▲ NooneAtAll3 3 hours ago

> why is this particular case BB(10) < G useful for understanding fast growing functions?

it's... not?

it is useful for understanding BB()

▲Jaxan 3 hours ago | parent [-]

First, an upper bound would be more useful to understand BB. But second, out of all large numbers, does this one give any information? We’ll have to see. The fact in itself is useless.

▲NooneAtAll3 3 hours ago | parent [-]

> First, an upper bound would be more useful to understand BB.

you can't have upper bound without breaking Turing and solving halting problem

> But second, out of all large numbers, does this one give any information? The fact in itself is useless.

yes, it gives info of "OMG BIG NUMBER I KNOW ABOUT, THAT'S SO COOL" quality, like all the rest of recreational mathematics :)

Graham's number is simply a nice checkpoint that invites everyone to learn more about function hierarchies

▲Jaxan 3 hours ago | parent [-]

> you can't have upper bound without breaking Turing and solving halting problem

Not in general, no. But for a fixed n, you can. For example, people have settled the exact value of BB(5).