An example of an infinite [[Abelian group]] which is a building block in the structure theory of such groups.
...}$. Reinhold Baer proved in 1937 that $\mathcal{B}$ is not [[Free Abelian group|free abelian]], whereas Specker proved in 1950 that every countable subgrou
775 bytes (113 words) - 07:30, 24 November 2023
[[Group|group]] $G$ with defect group $D$ (cf. also
[[Defect group of a block|Defect group of a block]]). Let $\nu$ be the discrete valuation defined on the integers
2 KB (352 words) - 14:21, 13 April 2012
...|Homology]]). A group which satisfies this condition is called a Whitehead group. An equivalent characterization is: $ A $
is a Whitehead group if and only if for every surjective homomorphism $ \pi $
4 KB (665 words) - 08:29, 6 June 2020
...unding the complexity of decompositions as graphs of groups for a discrete group.
...of Grushko's theorem [[#References|[a6]]], which asserts that if a [[Group|group]] $G$ is generated by a subset of cardinality $d$ and decomposes as a non-t
9 KB (1,405 words) - 15:30, 1 July 2020