deffunc H₁( Element of NAT ) -> R_eal = vol (G . $1);
thus for F1, F2 being Function of NAT,ExtREAL st ( for n being Element of NAT holds F1 . n = H₁(n) ) & ( for n being Element of NAT holds F2 . n = H₁(n) ) holds
F1 = F2 from BINOP_2:sch 1(); :: thesis: verum