  Using perturbative Quantum Chromodynamics, we compute dihadron fragmentation
functions for a large invariant mass of the dihadron pair. The main focus is on
the interference fragmentation function $H_1^{\open}$, which plays an important
role in spin physics of the nucleon. Our calculation also reveals that
$H_1^{\open}$ and the Collins fragmentation function have a closely related
underlying dynamics. By considering semi-inclusive deep-inelastic scattering,
we further show that collinear factorization in terms of dihadron fragmentation
functions, and collinear factorization in terms of single hadron fragmentation
functions provide the same result in the region of intermediate invariant mass.
