Let x0 of type ι be given.
Let x1 of type ι be given.
Let x2 of type ι be given.
Assume H0:
x2 ∈ setsum x0 x1.
Apply ordinal_binunion with
9d271.. x0,
9d271.. x1 leaving 2 subgoals.
The subproof is completed by applying unknownprop_1ec7349a6007c1951cbc9535ca5769b83316f6778bed19ab211854c4c6028c5d with x0.
The subproof is completed by applying unknownprop_1ec7349a6007c1951cbc9535ca5769b83316f6778bed19ab211854c4c6028c5d with x1.
Apply setsum_Inj_inv with
x0,
x1,
x2,
x2 ∈ V_ (ordsucc (binunion (9d271.. x0) (9d271.. x1))) leaving 3 subgoals.
The subproof is completed by applying H0.
Assume H2:
∃ x3 . and (x3 ∈ x0) (x2 = Inj0 x3).
Assume H2:
∃ x3 . and (x3 ∈ x1) (x2 = Inj1 x3).