Talk:Torsion subgroup

Why “torsion”?[edit]

Why is this called “torsion”? My only guess is that it has something to do with what happens to $y=x^{n}$ around $x=1$ as $n\to \infty$ —that is, the line twists about $y=x=1$ , the only element with finite order. Is that even close? —Ben FrantzDale 03:58, 25 January 2007 (UTC)[reply]

I would guess (but it's only a guess) that it comes from simplicial homology, where the "torsion coefficients" in some sense represent the twisting of the simplicial complex. The idea of using homology groups came later, and the torsion coefficients correspond to the torsion subgroups of the homology groups. --Zundark 12:08, 25 January 2007 (UTC)[reply]

clarification in definition[edit]

Can someone please clarify that A in the definition of p-torsion is an additive group? While it is clear to see for people already familiar with torsion, I believe there is some ambiguity for the beginner. 209.176.79.34 (talk) 23:56, 18 January 2010 (UTC)[reply]

I changed it to (A, +), just to be perfectly clear. The entire article, where needed, uses additive notation. 67.158.43.41 (talk) 21:57, 1 April 2011 (UTC)[reply]

Torsion-free abelian group[edit]

Currently, torsion-free abelian group redirects here, but I think its supposed to have its own article. See e.g. Torsion-free abelian groups of rank 1. The general case of non-rank-1 is not discussed here. linas (talk) 17:12, 2 September 2012 (UTC)[reply]

There is now a separate article for torsion-free abelian group. — Anita5192 (talk) 06:32, 6 December 2012 (UTC)[reply]