$W^{1, p}$ estimate for the solutions of elliptic equations whose coefficient
matrix can have large jump along the boundary of subdomains is obtained. The
principal coefficients are supposed to be in the John-Nirenberg space with
small BMO seminorms. The domain and subdomains are Reifenberg flat domains and
moreover, it has been shown that the estimates are uniform with respect to the
distance between the subdomains.Comment: 25 page