rewrite the current goal using
famunion_Empty (λx ⇒ ordsucc (SNoLev x)) (from left to right).
rewrite the current goal using binunion_idl 0 (from left to right).
Assume _ _ _.
We prove the intermediate
claim L1:
SNoLev (SNoCut 0 0) = 0.
Apply cases_1 (SNoLev (SNoCut 0 0)) H2 (λu ⇒ u = 0) to the current goal.
We will prove 0 = 0.
Use reflexivity.
Use transitivity with and 0.
An exact proof term for the current goal is L1.
Use symmetry.
An
exact proof term for the current goal is
SNoLev_0.
rewrite the current goal using L1 (from left to right).
Let beta be given.
We will prove False.
An exact proof term for the current goal is EmptyE beta Hb.
∎