Some remarks on regular subgroups of the affine group

Document Type : Research Paper

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Abstract

‎Let $V$ be a vector space over a field $F$ of characteristic $p\geq 0$ and let‎ ‎$T$ be a regular subgroup of the affine group $AGL(V)$‎. ‎In the finite dimensional case we show that‎, ‎if $T$ is abelian or $p>0$‎, ‎then $T$ is unipotent‎. ‎For $T$ abelian‎, ‎pushing forward some ideas used in [A‎. ‎Caranti‎, ‎F‎. ‎Dalla Volta and M‎. ‎Sala‎, ‎Abelian regular subgroups of the affine group and radical rings‎, ‎Publ‎. ‎Math‎. ‎Debrecen {\bf 69} (2006)‎, ‎297--308.]‎, ‎we show that the set $\left\{t-I\mid t\in T\right\}$ is a subalgebra‎ ‎of $End_F(F\oplus V)$‎, ‎which is nilpotent when $V$ has finite dimension‎. ‎This allows a rather systematic construction of abelian regular subgroups‎.

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A. Caranti, F. Dalla Volta and M. Sala (2006). Abelian regular subgroups of the affine group and radical rings. Publ. Math. Debrecen. 69, 297-308 P. Hegedus (2000). Regular subgroups of the Affine group. J. Algebra. 225, 740-742 J. E. Humphreys (1975). Linear algebraic groups. Springer.