We give a complete proof of the
following theorem which was conjectured by Jakob Nielsen for closed oriented
surfaces. Theorem 1 Let f : M → M be a homeomorphism of a compact surface.When M is closed, then f is isotopic to a diffeomorphism with N(f) fixedpoints, where N(f) is its Nielsen number. When M has boundary, N(f)should be replaced by the relative Nielsen number N(f;M,∂M) defined bySchirmer.
Another result is the inequality |L(f) − χ(M)|≤ N(f) − χ(M) when
χ(M) < 0, where L(f) is the Lefschetz number and χ(M) is the Euler
characteristic.