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Iterated Monodromy Group With Non-Martingale Fixed-Point Process

Jianfei He, Zheng Zhu

Abstract

We construct families of rational functions $f: \mathbb{P}^1_k \rightarrow \mathbb{P}^1_k$ of degree $d \geq 2$ over a perfect field $k$ with non-martingale fixed-point processes. Then for any normal variety $X$ over $\mathbb{P}_{\bar{k}}^N$, we give conditions on $f: X \rightarrow X$ to guarantee that the associated fixed-point process is a martingale. This work extends the previous work of Bridy, Jones, Kelsey, and Lodge on martingale conditions and answers their question on the existence of a non-martingale fixed-point process associated with the iterated monodromy group of a rational function.

Iterated Monodromy Group With Non-Martingale Fixed-Point Process

Abstract

We construct families of rational functions of degree over a perfect field with non-martingale fixed-point processes. Then for any normal variety over , we give conditions on to guarantee that the associated fixed-point process is a martingale. This work extends the previous work of Bridy, Jones, Kelsey, and Lodge on martingale conditions and answers their question on the existence of a non-martingale fixed-point process associated with the iterated monodromy group of a rational function.
Paper Structure (5 sections, 21 theorems, 47 equations, 4 figures)

This paper contains 5 sections, 21 theorems, 47 equations, 4 figures.

Key Result

Theorem 1.2

converge Let $Y_1, Y_2, \dots$ be a martingale. If each random variable $Y_i$ takes non-negative values, then the sequence $Y_1, Y_2, \dots$ converges almost surely.

Figures (4)

  • Figure 1: Ramification Portraits of $g \circ \psi$.
  • Figure 2: We get a level $4$ tree by decomposing $\phi$ as $g \circ h$.
  • Figure 3: Tree of cosets
  • Figure :

Theorems & Definitions (48)

  • Definition 1.1
  • Theorem 1.2
  • Theorem 1.3
  • Theorem 1.4
  • Theorem 1.5: Theorem \ref{['high']}
  • Definition 2.1
  • Lemma 2.2: Burnside's Lemma
  • Lemma 2.3: Coset Burnside's Lemma
  • proof
  • Lemma 2.4: Abhyankar's Lemma, codes
  • ...and 38 more