Step
*
of Lemma
not-inject
∀[T:Type]. ((∀x,y:T. Dec(x = y ∈ T))
⇒ (∀n:ℕ. ∀f:ℕn ⟶ T. ∃i:ℕn. ∃j:ℕi. ((f i) = (f j) ∈ T) supposing ¬Inj(ℕn;T;f)))
BY
{ (Auto THEN Unfold `inject` (-1) THEN RepeatFor 2 (((RWO "not-all-int_seg" (-1) THENA Auto) THEN D -1))) }
1
1. [T] : Type
2. ∀x,y:T. Dec(x = y ∈ T)@i
3. n : ℕ@i
4. f : ℕn ⟶ T@i
5. a1 : ℕn
6. a2 : ℕn
7. ¬(((f a1) = (f a2) ∈ T)
⇒ (a1 = a2 ∈ ℕn))
⊢ ∃i:ℕn. ∃j:ℕi. ((f i) = (f j) ∈ T)
Latex:
Latex:
\mforall{}[T:Type]
((\mforall{}x,y:T. Dec(x = y))
{}\mRightarrow{} (\mforall{}n:\mBbbN{}. \mforall{}f:\mBbbN{}n {}\mrightarrow{} T. \mexists{}i:\mBbbN{}n. \mexists{}j:\mBbbN{}i. ((f i) = (f j)) supposing \mneg{}Inj(\mBbbN{}n;T;f)))
By
Latex:
(Auto
THEN Unfold `inject` (-1)
THEN RepeatFor 2 (((RWO "not-all-int\_seg" (-1) THENA Auto) THEN D -1)))
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