22 Answers votes newest views recent 4Mathematical “urban legends” 2Cool problems to impress students with group theory 2Demonstrating that rigour is important 5Refereeing a Paper 8When and how is it appropriate for an undergraduate to email a professor out of the blue? 4Teaching proofs in the era of Google 3Why is it a good idea to study a ring by studying its modules? 2Interesting applications (in pure mathematics) of first-year calculus 12Rings in which every non-unit is a zero divisor 4How to introduce notions of flat, projective and free modules? 2What are the reasons for considering rings without identity? 2Examples of badly behaved derivatives 4Finite number of minimal ideals (2) 3Fundamental groups of topological groups. 3Group ring and left zero divisor. 4Isomorphism between direct sum of modules 1endomorphism ring of a finite-length module 11Direct sum of injective modules over non-Noetherian rings 3Terminology: Algebras where long strings of products are 0? 2elementary classification of artinian rings 2term for a “faithful” module 4When is a topological group Hausdorff (separated)?