Lax307052.SearchBounds
Quadratic space for the recursion stack
concepts/Lax307052/SearchBounds.lean · lax-307052
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Evidence
Each proof establishes this claim relative to its assumptions.
Lemma
The number of recursion frames is logarithmic in the configuration count. Multiplying this depth by the space for configurations and counters gives when bounds the input logarithm.
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| 1 | import Lax307052.ConfigurationGraph |
| 2 | import Lax434930.SpaceBounds |
| 3 | |
| 4 | /-! |
| 5 | --- |
| 6 | title: Quadratic space for the recursion stack |
| 7 | type: lemma |
| 8 | --- |
| 9 | The number of recursion frames is logarithmic in the configuration count. |
| 10 | Multiplying this depth by the space for configurations and counters gives |
| 11 | when bounds the input logarithm. |
| 12 | -/ |
| 13 | |
| 14 | namespace Lax307052.SearchBounds |
| 15 | |
| 16 | open Lax434930.SpaceMachines Lax434930.SpaceBounds BoundedConfigurations |
| 17 | |
| 18 | def stackSpace (M : Machine) (n s : ℕ) : ℕ := |
| 19 | (Nat.clog 2 (Fintype.card (Config M n s)) + 1) * (s + logSpace n + 1) |
| 20 | |
| 21 | axiom quadratic (M : Machine) : |
| 22 | ∃ c : ℕ, 0 < c ∧ ∀ n s, logSpace n ≤ s → stackSpace M n s ≤ c * s ^ 2 |
| 23 | |
| 24 | end Lax307052.SearchBounds |
| 25 |
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