Functorial languages in homological algebra and the lower central series

Abstract: This approach is based on the idea used to construct the so-called ${\bf fr}$-language. We construct such functorial languages as the ${\bf fr_{\infty}}$-language and other versions of it on categories of groups using the lower central series of groups of relations. In addition, we compute higher limits of the coinvariants of exterior powers, free Lie powers of modules of relations associated to free representations of groups. We show that such ${\bf fr_{\infty}}$-languages have remarkable properties when restricted to groups of finite homological dimension, torsion-free groups, and groups having no torsion up to $n$. Finally, we show how one can use functorial languages to transform categories/varieties of groups into certain spectra, which we call flux-spectra.