> Sufficiently large Turing computations, though theoretically finite, are not realizable in our universe. Should such computations be considered decidable or u

> Sufficiently large Turing computations, though theoretically finite, are not realizable in our universe. Should such computations be considered decidable or undecidable? In Practice, I think Undecidable is the only "correct" answer -- because our knowledge is still very incomplete. In Theory/Principle I think Decidable is the "correct" answer because there will very probably be limits that cannot be exceeded. ... but then, to reduce this to a simpler issue: The Halting Problem becomes trivial for any amount of finite state. It just takes a really, really long time (or a huge amount of space) to decide.