We consider the approximation of the total variation of a function by the family of
nonlocal and nonconvex functionals introduced by H. Brezis and H.-M. Nguyen in
a recent paper. The approximating functionals are defined through double
integrals in which every pair of points contributes according to some interaction
law.
We answer two open questions concerning the dependence of the Gamma-limit on
the interaction law. In the first result, we show that the Gamma-limit depends on the
full shape of the interaction law and not only on the values in a neighborhood
of the origin. In the second result, we show that there do exist interaction
laws for which the Gamma-limit coincides with the pointwise limit on smooth
functions.
The key argument is that for some special classes of interaction laws the
computation of the Gamma-limit can be reduced to studying the asymptotic behavior
of suitable multivariable minimum problems.
Keywords
Gamma-convergence, total variation, bounded-variation
functions, nonlocal functional, nonconvex functional