theorem Th49:
  for L be unital non empty multMagma for x be Element of L holds
  (power L).(x,1) = x
proof
  let L be unital non empty multMagma;
  let x be Element of L;
  0+1 = 1;
  hence (power L).(x,1) = (power L).(x,0) * x by Def7
    .= 1_L * x by Def7
    .= x by Def4;
end;
