
theorem Th27: :: Central0:
  for R be Skew-Field, s be Element of R
  holds 0.R is Element of centralizer s & 1_R is Element of centralizer s
proof
  let R be Skew-Field, s be Element of R;
A1: 0.R = 0.centralizer s by Def5;
  1.centralizer s = 1_R by Def5;
  hence thesis by A1;
end;
