The log-canonical model conjecture for varieties admitting endomorphisms

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Let XX be a normal variety, and let f ⁣:X→Xf\colon X\rightarrow X be an endomorphism of degree deg⁡(f)>1\deg(f)>1. Suppose that XX admits a log-canonical model

μ ⁣:Y→X.\mu\colon Y\rightarrow X.

Let EμlcE^{lc}_\mu be the sum of all the μ\mu-exceptional prime divisors, each with coefficient one, and let ZZ be an irreducible component of μ(Eμlc)\mu(E^{lc}_\mu). The log-canonical model conjecture. Up to replacing ff by some iterate, ZZ is totally invariant. In this case, ZZ is not contained in the ramification divisor RR, and the induced endomorphism f∣Z ⁣:Z→Zf|_Z\colon Z\rightarrow Z satisfies

deg⁡(f∣Z)=deg⁡(f).\deg(f|_Z)=\deg(f).

If moreover XX is projective and ff is polarised, then μ\mu is an isomorphism in codimension one. The statement concerns how endomorphisms interact with log-canonical models and their exceptional divisors. The surrounding discussion indicates that the existence of log-canonical models is known for certain pairs, while existence in general would follow from the minimal model program, including abundance; the status of this specific assertion is not resolved in the supplied text.

References

Primary source

Amaël Broustet and Andreas Höring, “Singularities of varieties admitting an endomorphism”, arXiv:1210.6254 (2017).

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