A CHARACTERISTIC p ANALOGUE OF PLT SINGULARITIES AND ADJOINT IDEALS
نویسنده
چکیده
We introduce a new variant of tight closure and give an interpretation of adjoint ideals via this tight closure. As a corollary, we prove that a log pair (X,∆) is plt if and only if the modulo p reduction of (X,∆) is divisorially F-regular for all large p ≫ 0. Here, divisorially F-regular pairs are a class of singularities in positive characteristic introduced by Hara and Watanabe [HW] in terms of Frobenius splitting. Also, we prove a subadditivity property of adjoint ideals making use of the above interpretation.
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