  Gromov-Witten, Gopakumar-Vafa, and Donaldson-Thomas invariants of Calabi-Yau
threefolds are compared. In certain situations, the Donaldson-Thomas invariants
are very easy to handle, sometimes easier than the other invariants. This point
is illustrated in several ways, especially by revisiting computations of
Gopakumar-Vafa invariants by Katz, Klemm, and Vafa in a rigorous mathematical
framework. This note is based on my talk at the 2004 Snowbird Conference on
String Geometry.
