Talk:Intersection of Subgroups is Subgroup

It seems to me that the result can be made (with almost identical proof) for a set of normal subgroups whose intersection is then also a normal subgroup. Would this reside on a separate page or can it just be added to this one?

I would also be inclined to remove the binary case, as its proof is not more illuminating than that for the general case. It could then be mentioned as an aside. Is this considered good practice? --Lord Farin 07:00, 10 October 2011 (CDT)


 * As suggested.


 * The one for normal subgroups already exists, I think - if not, then it ought to. --prime mover 13:26, 10 October 2011 (CDT)


 * Sorry but I reversed out your latest change because it reduces the result. Improved the proof that the intersection is the largest subgroup contained in all the subgroups. I think it's worth having it in, it's just awkward to prove without resorting to tautologies. --prime mover 15:36, 10 October 2011 (CDT)


 * I still think it is worthwhile having this and Intersection of Normal Subgroups is Normal look similar. The maximality result is omitted there. Also, but that may be a matter of taste, I prefer the notation used there (as I tried to implement) over the, imo somewhat vague, notation here. --Lord Farin 16:16, 10 October 2011 (CDT)


 * I think it's worth having them look different, myself. Depends where the original proof was plundered from, I suppose. In reality we want both ways of implementing the proof - but in this case the differences are sufficiently trivial to make it seem silly putting both proof techniques on the same page. --prime mover 16:32, 10 October 2011 (CDT)