We prove the intermediate
claim H3S:
SNo 3.
rewrite the current goal using Hdiv1 (from left to right) at position 1.
rewrite the current goal using Hdiv2 (from left to right) at position 1.
We prove the intermediate
claim H12eq:
add_SNo 1 2 = 3.
rewrite the current goal using H12eq (from left to right) at position 1.
We prove the intermediate
claim H3ne0:
3 ≠ 0.
We prove the intermediate
claim H3def:
3 = ordsucc 2.
rewrite the current goal using H3def (from left to right).
∎