For two nearby disjoint coassociative submanifolds C and C' in
a G2-manifold, we construct thin instantons with boundaries lying on C and
C' from regular J-holomorphic curves in C. It is a high dimensional
analogue of holomorphic stripes with boundaries on two nearby Lagrangian
submanifolds. We explain its relationship with the Seiberg-Witten
invariants for C. This is a joint work with Conan Leung and Xiaowei Wang.