reserve x,a for Int_position,
  s for State of SCMPDS;

theorem  :: see SCMPDS_3:32
  for a be Int_position ex i being Nat st a = intpos i
proof
  let a be Int_position;
  a in D by AMI_2:def 16;
  then consider x,y be object such that
A1: x in {1} and
A2: y in NAT and
A3: a=[x,y] by ZFMISC_1:84;
  reconsider k = y as Nat by A2;
  take k;
  thus intpos k=dl.k by SCMP_GCD:def 1
    .=a by A1,A3,TARSKI:def 1;
