theorem Z1:
(RootDC p) * (RootDC p) = DC p
proof
A: FAdj(F,{sqrt(DC p)}) is Subring of embField(canHomP X^2-(DC p))
   by FIELD_4:def 1;
thus (RootDC p) * (RootDC p)
   = sqrt(DC p) * sqrt(DC p) by A,FIELD_6:16 .= DC p by m1;
end;
