reserve p,q,r for FinSequence,
  x,y for object;

theorem Th6:
  for R being Relation, a being object holds <*a*> is RedSequence of R
proof
  let R be Relation, a be object;
  set p = <*a*>;
  thus len p > 0;
  let i be Nat;
  assume that
A1: i in dom p and
A2: i+1 in dom p;
A3: dom p = {1} by FINSEQ_1:2,38;
  then i = 1 by A1,TARSKI:def 1;
  hence thesis by A3,A2,TARSKI:def 1;
end;
