
theorem LMExtBit8:
  for K be non zero Nat,
  x be Element of BOOLEAN*
  st len x = K
  holds ExtBit(x,K) = x
  proof
    let K be non zero Nat,
    x be Element of BOOLEAN*;
    assume PA1: len x = K; then
    A1: K - len x =0;
    thus ExtBit(x,K) = x ^ (0* (K -' len x)) by PA1,Def20
    .=x ^ (0*0) by XREAL_0:def 2,A1
    .=x by FINSEQ_1:34;
  end;
