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by shwestrick 1393 days ago
Follow-up question, assuming we define BB(n) = max number of 1s written to tape for a halting machine of n states.

Does it make sense to compare BB(n) against A333479(n)?

It seems like A333479(n) grows much faster... my mind is jumping to the classic "problem" of being able to construct a lambda term of size O(2^n) using only O(n) steps. For a Turing machine, writing a symbol requires at least one step. But for lambda, you can generate large terms very quickly.

(Of course, this isn't a fundamental issue with lambda calculus, and there are other notions of size that are more "realistic". But focusing on just lambda calculus normal form sizes, how do we resolve this?)

1 comments

> Does it make sense to compare BB(n) against A333479(n)?

No, for proper comparison both should measure the argument size in bits. That's why my top comment talks about the number of bits needed to encode an n-state TM in a straightforward manner.

So compare BB(n) with A333479(n*2*(2+ceil(log(n+1)))).