theorem srecpeq2 (A: set) (_n1 _n2: nat): $ _n1 = _n2 -> (srecp A _n1 <-> srecp A _n2) $;
_n1 = _n2 -> _n1 = _n2
_n1 = _n2 -> (srecp A _n1 <-> srecp A _n2)