To limit the spread of novel coronavirus, governments across world implemented extraordinary physical distancing policies, such as stay-at-home orders. Numerous studies aim to estimate effects these policies. Many statistical and econometric methods, difference-in-differences, leverage repeated measurements, variation in timing policy effects, including COVID-19 context. Although methods are le...

A b s t r a c t In this paper, we briefly discuss the dynamic and functional approach to computer symbolic tensor analysis. The ccgrg package for Wolfram Language/Mathematica is used to illustrate this approach. Some examples of applications are attached.

In this article, we propose a fuzzy class relation assigning to each pair of finite fuzzy sets a degree to which they are equipollent, which indicates that they have the same number of elements. The concepts of fuzzy sets and fuzzy classes in the class of all countable sets are introduced, and several standard relations and constructions, such as the fuzzy power set and exponentiation, are defi...