reserve i,j,k,n,m for Nat,
  x,y,z,y1,y2 for object, X,Y,D for set,
  p,q for XFinSequence;
reserve k1,k2 for Nat;

theorem Th16: :: FINSEQ_8:5
  mid(p,1,k)=p|k
proof
  1-'1=0 by XREAL_1:232;
  hence thesis by Th10;
end;
