Rename `_11` and `_12` suffixes into `_1_1` and `_1_2`
Rename _11
and _12
into _1_1
and _1_2
, respectively. These suffixes are used for A → B1
and A → B2
variants of A ↔ B1 ∧ B2
lemmas.
The previous suffixes looked like lemma number 11 and 12, respectively.