Abstract
IfG is a finite group thend(G) denotes the minimal number of generators ofG. IfH andK are groups then the extension, 1 →H →G →K → 1, is called an outer extension ofK byH ifd(G)=d(H)+d(K). Let
be the class of groups containing all finitep-groupsG which has a presentation withd(G) = dimH 1(G,z p ) generators andr(G)=dimH 2 (G,Z p ) relations: in this article it is shown that ifK is a non cyclic group belonging to
andH is a finite abelian p-group then any outer extension ofK byH belongs to
.
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References
R. C. Lyndon,The cohomology theory of group extensions, Duke Math, J.15 (1948), 271–292.
C. T. C. Wall,Resolutions for extensions of groups, Proc. Cambridge Philos. Soc.57 (1961), 251–255.
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Wamsley, J.W. Minimal presentations for certain group extensions. Israel J. Math. 9, 459–463 (1971). https://doi.org/10.1007/BF02771460
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DOI: https://doi.org/10.1007/BF02771460