Saved in:
| Main Authors: | , , |
|---|---|
| Format: | Preprint |
| Published: |
2026
|
| Subjects: | |
| Online Access: | https://arxiv.org/abs/2605.08641 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1866918492316368896 |
|---|---|
| author | Huang, Wenduo Komorni, Vilmos Zou, Yuru |
| author_facet | Huang, Wenduo Komorni, Vilmos Zou, Yuru |
| contents | Given a pair $Q=(q_0,q_1)\in(1,\infty)^2$ with $q_0+q_1\ge q_0q_1$, a sequence $(c_i)\in\set{0,1}^\infty$ is called a $Q$-expansion of $x$ if<br/>\begin{equation*}<br/>x=\sum_{i=1}^{\infty}\frac{c_i}{q_{c_1}\cdots q_{c_i}}.<br/>\end{equation*}<br/>We primarily study the dynamical properties of the greedy and lazy maps, which are the piecewise-linear maps on the interval $I_Q=[0,\,1/(q_1-1)]$ defined by the corresponding algorithms for $Q$-expansions. <br/>We show that the greedy and lazy maps each of which has a unique absolutely continuous invariant probability measure, equivalent to the Lebesgue measure on the intervals<br/>\begin{equation*}<br/>\left[0,\frac{q_0}{q_1}\right)\qtq{and}\left(\frac{q_1}{q_0(q_1-1)}-1,\frac{1}{q_1-1}\right],<br/>\end{equation*}<br/>respectively. <br/>Furthermore, the corresponding dynamical systems are exact on $I_Q$. <br/>As a dynamical consequence, under the stronger condition $q_0+q_1>q_0q_1$ the set of points having unique $Q$-expansions has Lebesgue measure zero, and almost every $x\in I_{Q}$ admits a continuum of $Q$-expansions. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2605_08641 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Invariant measure for double base expansions Huang, Wenduo Komorni, Vilmos Zou, Yuru Dynamical Systems Number Theory 28D05, 11A63 Given a pair $Q=(q_0,q_1)\in(1,\infty)^2$ with $q_0+q_1\ge q_0q_1$, a sequence $(c_i)\in\set{0,1}^\infty$ is called a $Q$-expansion of $x$ if<br/>\begin{equation*}<br/>x=\sum_{i=1}^{\infty}\frac{c_i}{q_{c_1}\cdots q_{c_i}}.<br/>\end{equation*}<br/>We primarily study the dynamical properties of the greedy and lazy maps, which are the piecewise-linear maps on the interval $I_Q=[0,\,1/(q_1-1)]$ defined by the corresponding algorithms for $Q$-expansions. <br/>We show that the greedy and lazy maps each of which has a unique absolutely continuous invariant probability measure, equivalent to the Lebesgue measure on the intervals<br/>\begin{equation*}<br/>\left[0,\frac{q_0}{q_1}\right)\qtq{and}\left(\frac{q_1}{q_0(q_1-1)}-1,\frac{1}{q_1-1}\right],<br/>\end{equation*}<br/>respectively. <br/>Furthermore, the corresponding dynamical systems are exact on $I_Q$. <br/>As a dynamical consequence, under the stronger condition $q_0+q_1>q_0q_1$ the set of points having unique $Q$-expansions has Lebesgue measure zero, and almost every $x\in I_{Q}$ admits a continuum of $Q$-expansions. |
| title | Invariant measure for double base expansions |
| topic | Dynamical Systems Number Theory 28D05, 11A63 |
| url | https://arxiv.org/abs/2605.08641 |