theorem Th50:
  n|-> r is Element of REAL n
  proof
A1: r is Element of REAL by XREAL_0:def 1;
    set f = n|-> r;
    reconsider f as Function;
    f in Funcs(Seg n,REAL)
    proof
      f is Element of n-tuples_on REAL by A1,FINSEQ_2:112;
      then f in n-tuples_on REAL;
      hence thesis by FINSEQ_2:93;
    end;
    hence thesis by FINSEQ_2:93;
  end;
