  In this paper we address the vector problem of a 2D half-plane interfacial
crack loaded by a general asymmetric distribution of forces acting on its
faces. It is shown that the general integral formula for the evaluation of
stress intensity factors, as well as high-order terms, requires both symmetric
and skew-symmetric weight function matrices. The symmetric weight function
matrix is obtained via the solution of a Wiener-Hopf functional equation,
whereas the derivation of the skew-symmetric weight function matrix requires
the construction of the corresponding full field singular solution. The weight
function matrices are then used in the perturbation analysis of a crack
advancing quasi-statically along the interface between two dissimilar media. A
general and rigorous asymptotic procedure is developed to compute the
perturbations of stress intensity factors as well as high-order terms.
