specific-question I will also ask for some advice on the choice of the top-level tag for: Injective modules and Pontrjagin duals. I have used [tag;ac.commutative-algebra], since this is the top-level tag related to modules.
Forgive me for this naive question.
We consider the following lemma and its proof in Lang's algebra, Third Ed., published 1999, Chap. 20, section 4, page 784.
Every module is a submodule of an injective module.
For a module $M$, Lang defines its dual to be $M$^ = $Hom(M, \mathbb{Q}/\mathb...
@MartinSleziak new-tagmeta I waited a bit to see whether I get some response here. Eventually I created the export tag. (I did not create printing - perhaps having one tag for both purposes is enough.)
When I print an MO thread (using Chrome, at least), the font size is extremely small (8pt? nested indices are very hard to read, at least). Since I don't think this is easily fixable on the user side (at least not without MathJax getting all messed up), could we have a "printer-friendly" option o...
@MartinSleziak On second thought, the (reputation-leagues) tag on Mathematics Meta has only three questions, here on MathOverflow Meta I have seen only those two question which would fit under reputation-leagues. Probably using reputation for this is enough - a separate tag is not really needed.
Hanna moves in a lattice where every point can be represented by a pair of integers. She moves from point A to point B and then takes a turn 90 degrees right and starts moving till she reaches the first point on the lattice. Find what's the point she would reach? In essence the problem boils down...
Forgive me for this naive question.
We consider the following lemma and its proof in Lang's algebra, Third Ed., published 1999, Chap. 20, section 4, page 784.
Every module is a submodule of an injective module.
For a module $M$, Lang defines its dual to be $M$^ = $Hom(M, \mathbb{Q}/\mathb...
