Publikace na Matematicko-fyzikální fakulta |

2018

Moduli of path families are widely used to study Sobolev functions. Similarly, the recently introduced approximation (AM-) modulus is helpful in the theory of functions of bounded variation (BV) in R-n (Martio, 2016).

We continue this direction of research. Let Gamma(E) be the family of all paths which meet E subset of R-n.

We introduce the outer measure E bar right arrow AM(Gamma(E)) and compare it with other (n - 1)-dimensional measures. In particular, we show that AM(Gamma(E)) = 2H(n-1)(Gamma(E)) whenever E lies on a countably (n - 1)-rectifiable set.

Further, we study functions which have bounded variation on AM-a.e. path and we relate these functions to the classical BV functions which have only bounded essential variation on AM-a.e. path. We also characterize sets E of finite perimeter in terms of the AM-modulus of two path families naturally associated with E. (C) 2018 Elsevier Ltd.

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