Quas' Theorem #
We prove the italicized statement that we "must prove" in Theorem 4.42 from Automatic complexity: a computable measure of irregularity
theorem
claim443
{Q : Type u_1}
{A : Type u_2}
[Fintype Q]
[Fintype A]
[Nonempty A]
{Ξ΄ : A β Q β Q}
(hinj : β (a : A), Function.Injective (Ξ΄ a))
{c : Q}
{m : β}
(h : r m c = r m.succ c)
{M : β}
(hM : M > m)
{d : Q}
(hd : d β π‘ M c)
:
(Finset.filter (fun (w : Fin M β A) => ast Ξ΄ w c = d) Finset.univ).card β₯ Fintype.card A
Claim 4.43 in Automatic complexity
.
theorem
quas_family
{Q : Type u_1}
{A : Type u_2}
[Fintype Q]
[Fintype A]
{Ξ΄ : A β Q β Q}
(hinj : β (a : A), Function.Injective (Ξ΄ a))
{n : β}
{c : Q}
{d : Q}
(hβ : (Finset.filter (fun (w : Fin n β A) => ast Ξ΄ w c = d) Finset.univ).card β₯ 1)
(hβ : (Finset.filter (fun (w : Fin n β A) => ast Ξ΄ w c = d) Finset.univ).card < Fintype.card A)
:
Fintype.card Q β₯ n + 1
theorem
quas'
{Q : Type u_1}
{A : Type u_2}
[Fintype Q]
[Fintype A]
{Ξ΄ : A β Q β Q}
(hinj : β (a : A), Function.Injective (Ξ΄ a))
{n : β}
{c : Q}
{d : Q}
(hβ : (Finset.filter (fun (w : Fin n β A) => ast Ξ΄ w c = d) Finset.univ).card = 1)
(hA : Fintype.card A β₯ 2)
:
Fintype.card Q β₯ n + 1
Quas' Theorem.