“…We do not seek for full generality of energy functionals E here, since our main interest is focussed on the time-dependent mobility function m : R ≥0 ×R ≥0 → R ≥0 which turns (1.1) into a non-autonomous nonlinear evolution equation. When m does not explicitly depend on t, it is known that (1.1) possesses a variational structure [8,16,17], if m is nonnegative and concave on the interior of an interval [0, S], the so-called value space [29], with S ∈ R ≥0 ∪ {+∞}. In this work, we require that at each fixed time t ≥ 0, m(t, ·) is an admissible mobility in the sense of [8,16] (see condition (M1) below), where the corresponding value spaces [0, S(t)] are assumed to be expanding over time, i.e., S is nondecreasing.…”