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Step * 2 2 of Lemma fdl-1-join-irreducible


1. X : Type
2. x : Point(free-dl(X))@i
3. y : Point(free-dl(X))@i
4. ↑fdl-is-1(y)
⊢ ↑fdl-is-1(x ∨ y)
BY
{ (Subst' x ∨ y = y ∨ x ∈ Point(free-dl(X)) 0 THENA Auto) }

1
1. X : Type
2. x : Point(free-dl(X))@i
3. y : Point(free-dl(X))@i
4. ↑fdl-is-1(y)
⊢ ↑fdl-is-1(y ∨ x)

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Latex:

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Latex:

1.  X  :  Type
2.  x  :  Point(free-dl(X))@i
3.  y  :  Point(free-dl(X))@i
4.  \muparrow{}fdl-is-1(y)
\mvdash{}  \muparrow{}fdl-is-1(x  \mvee{}  y)


By

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Latex:
(Subst'  x  \mvee{}  y  =  y  \mvee{}  x  0  THENA  Auto)

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