  We give a proof of the Neilsen-Thurston classification theorem of a
homeomorphism f of a standard surface of finite type as either periodic,
pseudo-Anosov, or reducible. In the periodic case, we show that there exists an
integer n>0 such that f is isotopic to h with h^n isotopic to the identity.
This is the weaker version of the Nielsen-Thurston theorem.
