
theorem Th4:
  for G being real-weighted WGraph, EL be FF:ELabeling of G, source
  being Vertex of G holds dom (AP:CompSeq(EL,source).0) = {source}
proof
  let G be real-weighted WGraph, EL be FF:ELabeling of G, source be Vertex of
  G;
  AP:CompSeq(EL,source).0 = source .--> 1 by Def12;
  hence thesis;
end;
