arXivDaily arXiv每日学术速递 周一至周五更新
北美退伍军人节(Veterans Day),12 日无更新
arXiv 2005.13368math.AGmath.DSmath.NT
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小动力度不变子簇

Invariant subvarieties with small dynamical degree

Yohsuke Matsuzawa, Sheng Meng, Takahiro Shibata, De-Qi Zhang, Guolei Zhong

摘要:

设$f:X\to X $是特征为零的代数闭域上代数簇的支配自态射。我们考虑小动力度的$f$ -周期(不可约闭)子簇的集合$Σ_{f^{\infty}}$,$Σ_{f^{\infty}}$中极大元的子集$S_{f^{\infty}}$,以及$S_{f^{\infty}}$中$f$ -不变元的子集$S_f$.当$X$是射影的时,证明了$f$ -不变素因子的小动态度集合$P_f$的有限性,并给出了一个最优的基数上界$$\sharp P_{f^n}\le d_1(f)^n(1+o(1))$$为$n\to \infty$,其中$d_1(f)$是$f$的第一动态度.当$X$是一个代数群($f$是一个等距环的平移),或者是一个(不一定是完全的)环面簇($f$稳定了大环面)时,我们给出了一个最优上界$$\sharp S_{f^n}\le d_1(f)^{n\cdot\dim(X)}(1+o(1))$$为$n \to \infty$,这稍微推广了S. W.张为极化$f$。

英文摘要:

Let $f:X\to X $ be a dominant self-morphism of an algebraic variety over an algebraically closed field of characteristic zero. We consider the set $Σ_{f^{\infty}}$ of $f$-periodic (irreducible closed) subvarieties of small dynamical degree, the subset $S_{f^{\infty}}$ of maximal elements in $Σ_{f^{\infty}}$, and the subset $S_f$ of $f$-invariant elements in $S_{f^{\infty}}$. When $X$ is projective, we prove the finiteness of the set $P_f$ of $f$-invariant prime divisors with small dynamical degree, and give an optimal upper bound (of cardinality) $$\sharp P_{f^n}\le d_1(f)^n(1+o(1))$$ as $n\to \infty$, where $d_1(f)$ is the first dynamic degree of $f$. When $X$ is an algebraic group (with $f$ being a translation of an isogeny), or a (not necessarily complete) toric variety (with $f$ stabilizing the big torus), we give an optimal upper bound $$\sharp S_{f^n}\le d_1(f)^{n\cdot\dim(X)}(1+o(1))$$ as $n \to \infty$, which slightly generalizes a conjecture of S.-W. Zhang for polarized $f$.

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