
Let \(A\) be a finite-dimensional simple (associative) algebra over the field \(\mathbb{Q}\) of rational numbers. By an order of \(A\), we mean a subring \(R\) of \(A\), which contains the unit of \(A\) and forms a lattice in \(A\) (viewed as a vector space over \(\mathbb{Q}\)). It is well-known that orders exist, each one is contained in a maximal order of \(A\), and maximal orders share a common discriminant (called discriminant of \(A\)). The paper under review provides an algorithm for constructing a maximal order of \(A\). As a first step, the algorithm determines the decomposition of \(A\) into a direct product of simple algebras \(A_1,\dots,A_s\) (and solves the corresponding problem concerning the centre of \(A\)). The second step is to compute consecutively the discriminants and the local Schur indices of \(A_i\), \(i=1,\dots,s\). On this basis, a maximal order \(M_i\) of \(A_i\) is constructed, for each index \(i\), as a result of a repeated application of a canonical process used by \textit{H. Benz} and \textit{H. Zassenhaus} [in J. Number Theory 20, 282-298 (1985; Zbl 0593.16005)]; the subring \(M\) of \(A\) generated by \(M_i\), \(i=1,\dots,s\), is a maximal order of \(A\). Compared with the general case, the computations needed to implement the algorithm are easier in the special case where \(A\) has uniformly distributed invariants, e.g., when \(A\) is the centralizer algebra of a finite group representation.
local Schur indices, Ordinary representations and characters, Algebra and Number Theory, Other algebras and orders, and their zeta and \(L\)-functions, Schur index, Orders in separable algebras, maximal orders, Algebras and orders, and their zeta functions, algorithms, Computational aspects of associative rings (general theory), Finite-dimensional division rings, rational division algebras, Rational division algebra, Maximal order, local Hasse invariants, Wedderburn decompositions
local Schur indices, Ordinary representations and characters, Algebra and Number Theory, Other algebras and orders, and their zeta and \(L\)-functions, Schur index, Orders in separable algebras, maximal orders, Algebras and orders, and their zeta functions, algorithms, Computational aspects of associative rings (general theory), Finite-dimensional division rings, rational division algebras, Rational division algebra, Maximal order, local Hasse invariants, Wedderburn decompositions
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