Legacy existential work-tape interface #
The existing machine and fixed-machine run laws are reexported from the Internal kernel.
theorem Turing.MultiTapeTM.ComputableTidilyInTimeAndSpace.exists_onWords {α : Type u_1} {β : Type u_2} {f : α → β} {encIn : α ↪ List Bool} {encOut : β ↪ List Bool} {t s : α → ℕ} (h : ComputableTidilyInTimeAndSpace f encIn encOut t s) :
∃ (k : ℕ) (State : Type) (_ : Finite State) (tm : MultiTapeTM (k + 1 + 2) Bool State) (i : Fin (k + 1 + 2)) (o :
Fin (k + 1 + 2)),
i ≠ o ∧ ∀ (a : α),
tm.TransformsTapes
(fun (x : List Bool) (ws : Fin (k + 1 + 2) → List Bool) =>
ws = Function.update (fun (x : Fin (k + 1 + 2)) => []) i (encIn a))
(fun (x : List Bool) (ws ws' : Fin (k + 1 + 2) → List Bool) (emitted : List Bool) =>
ws' = Function.update ws o (encOut (f a)) ∧ emitted = [])
(t a + (encOut (f a)).length + 6) (s a + 2 * (encIn a).length + 2 * (encOut (f a)).length + 3 * k + 18)
A tidily computable function is computed by a machine with binary alphabet and finitely many
states that reads its input from a work tape i and writes its output to a different work tape
o, leaving every other work tape unchanged and emitting nothing.