A high-codimensional Yuan's inequality and its application to higher arithmetic degrees (2306.11591v2)

Abstract: In this article, we consider a dominant rational self-map $f:X \dashrightarrow X$ of a normal projective variety defined over a number field. We study the arithmetic degree $\alpha_k(f)$ for $f$ and $\alpha_k(f,V)$ of a subvariety $V$, which generalize the classical arithmetic degree $\alpha_1(f,P)$ of a point $P$. We generalize Yuan's arithmetic version of Siu's inequality to higher codimensions and utilize it to demonstrate the existence of the arithmetic degree $\alpha_k(f)$. Furthermore, we establish the relative degree formula $\alpha_k(f)=\max{\lambda_k(f),\lambda_{k-1}(f)}$. In addition, we prove several basic properties of the arithmetic degree $\alpha_k(f, V)$ and establish the upper bound $\overline{\alpha}{k+1}(f, V)\leq \max{\lambda{k+1}(f),\lambda_{k}(f)}$, which generalizes the classical result $\overline{\alpha}_f(P)\leq \lambda_1(f)$. Finally, we discuss a generalized version of the Kawaguchi-Silverman conjecture that was proposed by Dang et al, and we provide a counterexample to this conjecture.