Integral semihereditary orders, extremality, and Henselization

[摘要] In this paper, we study integral semihereditary orders over a valuation ring in a finite-dimensional simple Artinian ring. In the first section we prove that such orders are extremal. Consequently, in a central division algebra admitting a total valuation ring, the intersection of all the conjugates of the total valuation ring is the unique integral semihereditary order over the center of the total valuation ring. In the second section we characterize, up to conjugacy, integral semihereditary orders over a Henselian valuation ring. In the last section we show that an integral order R over an arbitrary valuation ring V is semihereditary iff its Henselization, R x V-v(h), where V-h is the Henselization of V, is a semihereditary V-h-order. In this case, there is an inclusion preserving bijective correspondence between semihereditary V-orders inside R and semihereditary V-h-orders inside R x V-v(h). (C) 1997 Academic Press.

[发布日期] 1997-03-15