Post #1844254

@slava In "Monoids of natural Numbers" Steven Finch says: "A numerical monoid \(S\) is a subset of \(\mathbf{N}\) that is closed under addition, contains 0, and has a finite complement in \(\mathbf{N}\). (Most authors use the phrase ``numerical semigroup''' but semigroups by defintion need not contain 0, hence the usage is puzzling.)" https://studylib.net/doc/7964892/monoids-of-natural-numbers-steven-finch-march-17--2009-let-n