Let a be given.
Let j be given.
rewrite the current goal using Haj (from left to right).
We prove the intermediate
claim HfjR:
apply_fun f j ∈ R.
We prove the intermediate
claim HgjR:
apply_fun g j ∈ R.
rewrite the current goal using Hdef1 (from left to right).
rewrite the current goal using Hdef2 (from right to left).
Let a be given.
Let j be given.
rewrite the current goal using Haj (from left to right).
We prove the intermediate
claim HfjR:
apply_fun f j ∈ R.
We prove the intermediate
claim HgjR:
apply_fun g j ∈ R.
rewrite the current goal using Hdef1 (from left to right).
rewrite the current goal using Hdef2 (from right to left).
∎