theorem grecaux1eq4 (K: set) (x z _n1 _n2: nat): $ _n1 = _n2 -> grecaux1 K x z _n1 = grecaux1 K x z _n2 $;
_n1 = _n2 -> _n1 = _n2
_n1 = _n2 -> grecaux1 K x z _n1 = grecaux1 K x z _n2