reserve k,n,i,j for Nat;

theorem Th14:
  for K being Ring, n being Nat, p being Element of
  Permutations n, i being Nat st i in Seg n holds p.i in Seg n
proof
  let K be Ring, n be Nat, p be Element of Permutations(n),i be
  Nat;
A1: p is Permutation of Seg n by MATRIX_1:def 12;
  assume i in Seg n;
  hence thesis by A1,FUNCT_2:5;
end;
