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$\DeclareMathOperator\SL{SL}\DeclareMathOperator\tr{\mathsf{tr}}$$\SL_2(\mathbb{N})$ is a free monoid on the generators $$ L=\begin{pmatrix}1&0\\1&1\end{pmatrix},\quad R=\begin{pmatrix}1&1\\0&1\\\end{pmatrix}. $$ Let $\SL_2^{(n)}(\mathbb{N})$ designate the set of words of length $n$ in these generators. I have a couple of questions about this family that seem within reach (i.e. are already known or could be determined by the good folks of mathoverflow).

  1. What is the distribution of $\{\tr(M) : M\in \SL_2^{(n)}(\mathbb{N})\}$?
  2. What is the distribution of $\{\|M\|_{\infty} : M\in \SL_2^{(n)}(\mathbb{N})\}$?
  3. What is the joint distribution of the two quantities above?

I'd prefer to know the limiting distribution $n\to\infty$ and some useful error term (if they exist), but any non-trivial bounds are welcome, or approximations to relevant functions of the matrices as functions of the $\{L,R\}$ decomposition $$ M(w)=\prod_{i=0}^{n-1}G_{w_i}, \quad w\in\{0,1\}^n, \quad G_0=L, \quad G_1=R. $$

Here are a few pictures (of dubious quality); scatterplot on top of bar plot (could've just done a histogram but was more curious about some of the exact values).

Traces, $n=15,20,25$: trace counts for length 15 words trace counts for length 20 words trace counts for length 25 words

$L^{\infty}$, $n=15,20,25$: sup norm counts for length 15 words sup norm counts for length 20 words sup norm counts for length 25 words

Joint $n=15$ (the linear relationship seems to be $\tr(M)\approx \frac{9}{8}\|M\|_{\infty}$): Joint n = 15


EDIT: Thought I'd throw some gifs of distributions with changing $n$. Trace: enter image description here Sup norm: enter image description here

$\DeclareMathOperator\SL{SL}\DeclareMathOperator\tr{\mathsf{tr}}$$\SL_2(\mathbb{N})$ is a free monoid on the generators $$ L=\begin{pmatrix}1&0\\1&1\end{pmatrix},\quad R=\begin{pmatrix}1&1\\0&1\\\end{pmatrix}. $$ Let $\SL_2^{(n)}(\mathbb{N})$ designate the set of words of length $n$ in these generators. I have a couple of questions about this family that seem within reach (i.e. are already known or could be determined by the good folks of mathoverflow).

  1. What is the distribution of $\{\tr(M) : M\in \SL_2^{(n)}(\mathbb{N})\}$?
  2. What is the distribution of $\{\|M\|_{\infty} : M\in \SL_2^{(n)}(\mathbb{N})\}$?
  3. What is the joint distribution of the two quantities above?

I'd prefer to know the limiting distribution $n\to\infty$ and some useful error term (if they exist), but any non-trivial bounds are welcome, or approximations to relevant functions of the matrices as functions of the $\{L,R\}$ decomposition $$ M(w)=\prod_{i=0}^{n-1}G_{w_i}, \quad w\in\{0,1\}^n, \quad G_0=L, \quad G_1=R. $$

Here are a few pictures (of dubious quality); scatterplot on top of bar plot (could've just done a histogram but was more curious about some of the exact values).

Traces, $n=15,20,25$: trace counts for length 15 words trace counts for length 20 words trace counts for length 25 words

$L^{\infty}$, $n=15,20,25$: sup norm counts for length 15 words sup norm counts for length 20 words sup norm counts for length 25 words

Joint $n=15$ (the linear relationship seems to be $\tr(M)\approx \frac{9}{8}\|M\|_{\infty}$): Joint n = 15

$\DeclareMathOperator\SL{SL}\DeclareMathOperator\tr{\mathsf{tr}}$$\SL_2(\mathbb{N})$ is a free monoid on the generators $$ L=\begin{pmatrix}1&0\\1&1\end{pmatrix},\quad R=\begin{pmatrix}1&1\\0&1\\\end{pmatrix}. $$ Let $\SL_2^{(n)}(\mathbb{N})$ designate the set of words of length $n$ in these generators. I have a couple of questions about this family that seem within reach (i.e. are already known or could be determined by the good folks of mathoverflow).

  1. What is the distribution of $\{\tr(M) : M\in \SL_2^{(n)}(\mathbb{N})\}$?
  2. What is the distribution of $\{\|M\|_{\infty} : M\in \SL_2^{(n)}(\mathbb{N})\}$?
  3. What is the joint distribution of the two quantities above?

I'd prefer to know the limiting distribution $n\to\infty$ and some useful error term (if they exist), but any non-trivial bounds are welcome, or approximations to relevant functions of the matrices as functions of the $\{L,R\}$ decomposition $$ M(w)=\prod_{i=0}^{n-1}G_{w_i}, \quad w\in\{0,1\}^n, \quad G_0=L, \quad G_1=R. $$

Here are a few pictures (of dubious quality); scatterplot on top of bar plot (could've just done a histogram but was more curious about some of the exact values).

Traces, $n=15,20,25$: trace counts for length 15 words trace counts for length 20 words trace counts for length 25 words

$L^{\infty}$, $n=15,20,25$: sup norm counts for length 15 words sup norm counts for length 20 words sup norm counts for length 25 words

Joint $n=15$ (the linear relationship seems to be $\tr(M)\approx \frac{9}{8}\|M\|_{\infty}$): Joint n = 15


EDIT: Thought I'd throw some gifs of distributions with changing $n$. Trace: enter image description here Sup norm: enter image description here

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LSpice
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Distribution of traces and max entries of words of fixed length in $\mathrm$\operatorname{SL}_2(\mathbb{N})$

$\DeclareMathOperator\SL{SL}$$\SL_2(\mathbb{N})$$\DeclareMathOperator\SL{SL}\DeclareMathOperator\tr{\mathsf{tr}}$$\SL_2(\mathbb{N})$ is a free monoid on the generators $$ L=\left(\begin{array}{cc}1&0\\1&1\\\end{array}\right),\quad R=\left(\begin{array}{cc}1&1\\0&1\\\end{array}\right). $$$$ L=\begin{pmatrix}1&0\\1&1\end{pmatrix},\quad R=\begin{pmatrix}1&1\\0&1\\\end{pmatrix}. $$ Let $\SL_2^{(n)}(\mathbb{N})$ designate the set of words of length $n$ in these generators. I have a couple of questions about this family that seem within reach (i.e. are already known or could be determined by the good folks of mathoverflow).

  1. What is the distribution of $\{\mathsf{tr}(M) : M\in \SL_2^{(n)}(\mathbb{N})\}$$\{\tr(M) : M\in \SL_2^{(n)}(\mathbb{N})\}$?
  2. What is the distribution of $\{\|M\|_{\infty} : M\in \SL_2^{(n)}(\mathbb{N})\}$?
  3. What is the joint distribution of the two quantities above?

I'd prefer to know the limiting distribution $n\to\infty$ and some useful error term (if they exist), but any non-trivial bounds are welcome, or approximations to relevant functions of the matrices as functions of the $\{L,R\}$ decomposition $$ M(w)=\prod_{i=0}^{n-1}G_{w_i}, \quad w\in\{0,1\}^n, \quad G_0=L, \quad G_1=R, $$$$ M(w)=\prod_{i=0}^{n-1}G_{w_i}, \quad w\in\{0,1\}^n, \quad G_0=L, \quad G_1=R. $$

Here are a few pictures of (dubiousof dubious quality); scatterplot on top of bar plot (could've just done a histogram but was more curious about some of the exact values).

Traces, $n=15,20,25$: enter image description heretrace counts for length 15 words enter image description heretrace counts for length 20 words enter image description heretrace counts for length 25 words

$L^{\infty}$, $n=15,20,25$: enter image description heresup norm counts for length 15 words enter image description heresup norm counts for length 20 words enter image description heresup norm counts for length 25 words

Joint $n=15$ (the linear relationship seems to be $\mathsf{tr}(M)\approx \frac{9}{8}\|M\|_{\infty}$$\tr(M)\approx \frac{9}{8}\|M\|_{\infty}$): enter image description hereJoint n = 15

Distribution of traces and max entries of words of fixed length in $\mathrm{SL}_2(\mathbb{N})$

$\DeclareMathOperator\SL{SL}$$\SL_2(\mathbb{N})$ is a free monoid on the generators $$ L=\left(\begin{array}{cc}1&0\\1&1\\\end{array}\right),\quad R=\left(\begin{array}{cc}1&1\\0&1\\\end{array}\right). $$ Let $\SL_2^{(n)}(\mathbb{N})$ designate the set of words of length $n$ in these generators. I have a couple of questions about this family that seem within reach (i.e. are already known or could be determined by the good folks of mathoverflow).

  1. What is the distribution of $\{\mathsf{tr}(M) : M\in \SL_2^{(n)}(\mathbb{N})\}$?
  2. What is the distribution of $\{\|M\|_{\infty} : M\in \SL_2^{(n)}(\mathbb{N})\}$?
  3. What is the joint distribution of the two quantities above?

I'd prefer to know the limiting distribution $n\to\infty$ and some useful error term (if they exist), but any non-trivial bounds are welcome, or approximations to relevant functions of the matrices as functions of the $\{L,R\}$ decomposition $$ M(w)=\prod_{i=0}^{n-1}G_{w_i}, \quad w\in\{0,1\}^n, \quad G_0=L, \quad G_1=R, $$

Here are a few pictures of (dubious quality); scatterplot on top of bar plot (could've just done a histogram but was more curious about some of the exact values).

Traces, $n=15,20,25$: enter image description here enter image description here enter image description here

$L^{\infty}$, $n=15,20,25$: enter image description here enter image description here enter image description here

Joint $n=15$ (the linear relationship seems to be $\mathsf{tr}(M)\approx \frac{9}{8}\|M\|_{\infty}$): enter image description here

Distribution of traces and max entries of words of fixed length in $\operatorname{SL}_2(\mathbb{N})$

$\DeclareMathOperator\SL{SL}\DeclareMathOperator\tr{\mathsf{tr}}$$\SL_2(\mathbb{N})$ is a free monoid on the generators $$ L=\begin{pmatrix}1&0\\1&1\end{pmatrix},\quad R=\begin{pmatrix}1&1\\0&1\\\end{pmatrix}. $$ Let $\SL_2^{(n)}(\mathbb{N})$ designate the set of words of length $n$ in these generators. I have a couple of questions about this family that seem within reach (i.e. are already known or could be determined by the good folks of mathoverflow).

  1. What is the distribution of $\{\tr(M) : M\in \SL_2^{(n)}(\mathbb{N})\}$?
  2. What is the distribution of $\{\|M\|_{\infty} : M\in \SL_2^{(n)}(\mathbb{N})\}$?
  3. What is the joint distribution of the two quantities above?

I'd prefer to know the limiting distribution $n\to\infty$ and some useful error term (if they exist), but any non-trivial bounds are welcome, or approximations to relevant functions of the matrices as functions of the $\{L,R\}$ decomposition $$ M(w)=\prod_{i=0}^{n-1}G_{w_i}, \quad w\in\{0,1\}^n, \quad G_0=L, \quad G_1=R. $$

Here are a few pictures (of dubious quality); scatterplot on top of bar plot (could've just done a histogram but was more curious about some of the exact values).

Traces, $n=15,20,25$: trace counts for length 15 words trace counts for length 20 words trace counts for length 25 words

$L^{\infty}$, $n=15,20,25$: sup norm counts for length 15 words sup norm counts for length 20 words sup norm counts for length 25 words

Joint $n=15$ (the linear relationship seems to be $\tr(M)\approx \frac{9}{8}\|M\|_{\infty}$): Joint n = 15

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