Name for number of elements of order (1 or) 2 in an abelian group - MathOverflow most recent 30 from http://mathoverflow.net2013-05-24T13:51:29Zhttp://mathoverflow.net/feeds/question/18263http://www.creativecommons.org/licenses/by-nc/2.5/rdfhttp://mathoverflow.net/questions/18263/name-for-number-of-elements-of-order-1-or-2-in-an-abelian-groupName for number of elements of order (1 or) 2 in an abelian groupMark Meckes2010-03-15T13:23:47Z2010-03-15T13:23:47Z
<p>Let $G$ be an (additive) abelian group. Is there a concise, standard term for the order of the kernel $K$ of the endomorphism $g\mapsto 2g$? Or alternatively, for the index of $K$?</p>