Submission date: 12 April 2019

Abstract:

In this survey the role of implications of positive formulas -- finitary and infinitary -- is dicussed, in general and in module categories, where they seem of particular importance. A list of algebraic examples is given, some old, some rather new, and properties are derived from the particular shape of implications involved.

Mathematics Subject Classification: 03C60, 13L05, 16D40, 16D50, 16D90, 16S90, 16U30

Keywords and phrases:

Full text arXiv 1904.06016: pdf, ps.