Let x0 of type ι → ο be given.
Assume H0:
∀ x1 . ordinal x1 ⟶ (∀ x2 . In x2 x1 ⟶ x0 x2) ⟶ x0 x1.
Apply unknownprop_acac0f89c78f08b97a9fe27ba4af5f929f74e43a9a77a0beb38d70975279c8b8 with
λ x1 . ordinal x1 ⟶ x0 x1.
Let x1 of type ι be given.
Assume H1:
∀ x2 . In x2 x1 ⟶ ordinal x2 ⟶ x0 x2.
Apply H0 with
x1 leaving 2 subgoals.
The subproof is completed by applying H2.
Let x2 of type ι be given.
Apply H1 with
x2 leaving 2 subgoals.
The subproof is completed by applying H3.
Apply unknownprop_df95567eaac7dcf742571a06351d685ef037c3575a0b273f643efe646824ac1a with
x1,
x2 leaving 2 subgoals.
The subproof is completed by applying H2.
The subproof is completed by applying H3.