While the forward trajectory of a point in discrete dynamical system is always unique, general can have infinitely many backward trajectories. The union limit points all trajectories through $x$ was called by M.~Hero "special $\alpha$-limit" ($s\alpha$-limit for short) $x$. In this article we show that there hierarchy $s\alpha$-limits under iterations S-unimodal map: size $s\alpha$-limit increa...

Ordinal classification tasks are present in a large number of different domains. However, common losses for deep neural networks, such as cross-entropy, do not properly weight the relative ordering between classes. For that reason, many have been proposed literature, which model output probabilities following unimodal distribution. This manuscript reviews these on three datasets and suggests po...