Let X, Tx, A, B, C, x, a and b be given.
We prove the intermediate
claim HaV:
a ∈ V.
rewrite the current goal using HVdef (from right to left).
An exact proof term for the current goal is HaComp.
We prove the intermediate
claim HbV:
b ∈ V.
rewrite the current goal using HVdef (from right to left).
An exact proof term for the current goal is HbComp.
The rest of this subproof is missing.
∎