The Lefschetz number and fixed point index can be thought of as two different
descriptions of the same invariant. The Lefschetz number is algebraic and
defined using homology. The index is defined more directly from the topology
and is a stable homotopy class. Both the Lefschetz number and index admit
generalizations to coincidences and the comparison of these invariants retains
its central role. In this paper we show that the identification of the
Lefschetz number and index using formal properties of the symmetric monoidal
trace extends to coincidence invariants. This perspective on the coincidence
index and Lefschetz number also suggests difficulties for generalizations to a
coincidence Reidemeister trace.Comment: Minor revisio
