converges strongly in L2 and weakly in BV to the minimizer
of the variational problem (1.6). Here our method is to
study firstly the approximation problem of (1.7)–(1.9). Then
some uniform estimates of the approximation solutions are
derived, which enable us to pass to the limit in the approximate
problem to get the existence of weak solutions to (1.7)–
(1.9).