Nuprl - Proof: union sigma inverses 1

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At: union sigma inverses 1

1. A : Type
2. B : Type

InvFuns(A+B;i:

if i=

A else B fi;union_to_sigma;sigma_to_union)

By:

Analyze

Generated subgoals:

1 3. x : A+B
sigma_to_union(union_to_sigma(x)) = x
3 steps

2 3. y : i:2if i=0 A else B fi
union_to_sigma(sigma_to_union(y)) = y
2 steps

About:

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1	3. x : A+B sigma_to_union(union_to_sigma(x)) = x	3 steps
2	3. y : i:2if i=0 A else B fi union_to_sigma(sigma_to_union(y)) = y	2 steps