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On the Lie algebra structure of \(HH^1(A)\) of a finite-dimensional algebra \(A\). (English) Zbl 1441.16013

In this paper, the authors study the Lie algebra \(HH^1(A)\), where \(A\) is a split finite dimensional associative unital algebra over a field \(k\) and prove some interesting results. Firstly, it is shown that if the Ext-quiver of \(A\) is a simple directed graph, then the derived Lie subalgebra of \(HH^1(A)\) is nilpotent and in particular, the Lie algebra \(HH^1(A)\) is solvable. The next main result is, if the Ext-quiver of \(A\) has no loops and at most two parallel arrows in any direction, and if \(HH^1(A)\) is a simple Lie algebra, then char \((k)\neq 2\) and \(HH^1(A)\cong sl_2(k)\). Finally, for an algebraically closed field \(k\), they study a finite-dimensional symmetric \(k\)-algebra \(A\) with a quiver that has a vertex with a single loop and prove that if \(HH^1(A)\) is a simple Lie algebra, then char \((k) =p >2\) and \(HH^1(A)\) is isomorphic to either \(sl_2(k)\) or the Witt Lie algebra \(W= \mathrm{Der}(k[x]/(x^p))\). They conclude the paper with few nice examples.

MSC:

16E40 (Co)homology of rings and associative algebras (e.g., Hochschild, cyclic, dihedral, etc.)
16G30 Representations of orders, lattices, algebras over commutative rings
16D90 Module categories in associative algebras
17B50 Modular Lie (super)algebras

References:

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