Invariance of topological entropy under complete metrized field extension

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Let kk be a complete metrized field, let XX be a projective variety defined over kk, and let f ⁣:X⇢Xf\colon X\dashrightarrow X be a dominant rational map. For any complete metrized field extension K/kK/k, let XKX_K be the base change of XX and let fK ⁣:XK⇢XKf_K\colon X_K\dashrightarrow X_K be the rational self-map induced by base change. Entropy-invariance problem. One asks whether

htop⁡(fK)=htop⁡(f).\operatorname{h_{top}}(f_K)=\operatorname{h_{top}}(f).

The problem concerns whether the topological entropy defined for rational maps is unchanged after extending the complete metrized ground field. The source presents this as an open problem; for regular maps, the entropy agrees with that of the induced action on the Berkovich analytification.

References

Primary source

Charles Favre, Tuyen Trung Truong and Junyi Xie, “Topological entropy of a rational map over a complete metrized field”, arXiv:2208.00668 (2022).

Additional references

2 papers in this index state this conjecture (2020–2022). The statement above is taken from the most recent of them; the others are arXiv:2008.11637.

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