Identification of the F-different with the different

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Let RR be an FF-finite normal local ring of characteristic p>0p>0, let X:=Spec⁡RX:=\operatorname{Spec} R, and let D+BD+B be an effective Q\mathbb{Q}-divisor on XX, where DD is a normal prime divisor with defining ideal Q⊆RQ\subseteq R and DD is not contained in Supp⁡B\operatorname{Supp} B. Let BR/QB_{R/Q} be the effective Q\mathbb{Q}-divisor on D=Spec⁡(R/Q)D=\operatorname{Spec}(R/Q) induced by the restriction of the Frobenius map associated to (X,D+B)(X,D+B). The different BDB_D of (X,D+B)(X,D+B) on DD is the divisor defined by adjunction. The F-different identification. The divisors coincide:

BR/Q=BD.B_{R/Q}=B_D.

This identifies the divisor obtained from Frobenius restriction with the classical different, linking FF-singularity methods with adjunction. The source gives no resolution status for this claim.

References

Primary source

Osamu Fujino, Karl Schwede and Shunsuke Takagi, “Supplements to non-lc ideal sheaves”, arXiv:1004.5170 (2011).

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