Metamath Proof Explorer


Theorem bj-inftyexpitaufo

Description: The function inftyexpitau written as a surjection with domain and range. (Contributed by BJ, 4-Feb-2023)

Ref Expression
Assertion bj-inftyexpitaufo +∞e:onto∞N

Proof

Step Hyp Ref Expression
1 opex {R1stx𝑹V
2 df-bj-inftyexpitau +∞e=x{R1stx𝑹
3 1 2 fnmpti +∞eFn
4 dffn4 +∞eFn+∞e:ontoran+∞e
5 3 4 mpbi +∞e:ontoran+∞e
6 df-bj-ccinftyN msub
7 6 eqcomi ran+∞e=∞N
8 foeq3 ran+∞e=∞N+∞e:ontoran+∞e+∞e:onto∞N
9 7 8 ax-mp +∞e:ontoran+∞e+∞e:onto∞N
10 5 9 mpbi +∞e:onto∞N