Abstract Foreman and Weiss [Measure preserving diffeomorphisms of the torus are unclassifiable. Preprint , 2020, arXiv:1705.04414] obtained an anti-classification result for smooth ergodic diffeomorphisms, up to measure isomorphism, by using a functor $\mathcal {F}$ (see [Foreman Weiss, From odometers circular systems: global structure theorem. J. Mod. Dyn. 15 (2019), 345–423]) mapping odometer...

This paper shows the equivalence of applicative similarity and contextual approximation, and hence also of bisimilarity and contextual equivalence, in the deterministic call-by-need lambda calculus with letrec. Bisimilarity simplifies equivalence proofs in the calculus and opens a way for more convenient correctness proofs for program transformations. Although this property may be a natural one...

Previous research has shown that the qualities of nuptial gifts among nonhumans and marriage-related property transfers in human societies such as bridewealth and dowry covary with aspects of mate quality. This article explores this issue for another type of marriage-related property transfer: engagement rings. We obtained data on engagement ring costs and other variables through a mail survey ...