  The three string vertex for Type IIB superstrings in a maximally
supersymmetric plane-wave background can be constructed in a light-cone gauge
string field theory formalism. The detailed formula contains certain Neumann
coefficients, which are functions of a momentum fraction y and a mass parameter
\mu. This paper reviews the derivation of useful explicit expressions for these
Neumann coefficients generalizing flat-space (\mu = 0) results obtained long
ago. These expressions are then used to explore the large \mu asymptotic
behavior, which is required for comparison with dual perturbative gauge theory
results. The asymptotic formulas, exact up to exponentially small corrections,
turn out to be surprisingly simple.
