Tobias Moede - Coclass theory for nilpotent associative algebras

Réalisation : 30 juin 2022 - Mise en ligne : 19 octobre 2022
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The coclass of a finite p-group of order p^n and class c is defined as n-c. Using coclass as the primary invariant in the investigation of finite p-groups turned out to be a very fruitful approach. Together with Bettina Eick, we have developed a coclass theory for nilpotent associative algebras over fields. A central tool are the coclass graphs associated with the algebras of a fixed coclass. The graphs for coclass zero are well understood. We give a full description for coclass one and explore graphs for higher coclasses.  We prove several structural results for coclass graphs, which yield results in the flavor of the coclass theorems for finite p-groups. The most striking observation  in our experimental data is that for finite fields all of these graphs seem to exhibit a periodic pattern. A similar periodicity in the graphs for finite p-groups has  been proved independently by du Sautoy using the theory of zeta functions and by Eick & Leedham-Green using cohomological methods. We give an outlook on how a proof might proceed and how the periodicity may be exploited to describe the infinitely many nilpotent associative F-algebras of a fixed coclass by a finite set of data.

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