reserve x,y,z for boolean object;
reserve i,j,k for Nat;
reserve n for non zero Nat;
reserve x,y,z1,z2 for Tuple of n, BOOLEAN;

theorem Th14:
  for z1 being Tuple of 1,BOOLEAN holds z1= <*FALSE*> or z1=<*TRUE *>
proof
  let z1 be Tuple of 1,BOOLEAN;
A1: ex B being Element of BOOLEAN st z1=<*B*> by FINSEQ_2:97;
  per cases by XBOOLEAN:def 3;
  suppose
    z1/.1 = FALSE;
    hence thesis by A1,FINSEQ_4:16;
  end;
  suppose
    z1/.1 = TRUE;
    hence thesis by A1,FINSEQ_4:16;
  end;
end;
