reserve n,i,j,k for Nat;
reserve T for TuringStr,
  s for All-State of T;

theorem Th28:
  dom [+] c= 2-tuples_on NAT
proof
  arity (1 proj 1)=1;
  then dom [+] c= (1+1)-tuples_on NAT by COMPUT_1:56;
  hence thesis;
end;
