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Added a full account of orbits for J and 7x7 binary matrices
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There are counterexamples for $Q=J$.

Here is a binary $6\times7$ binary matrix $M$ that belongs to an orbit of $L_J$$\mathcal{L}_J$ with period $3$:

$\begin{matrix} 1&1&1&0&0&0&0\\ 1&1&0&1&1&0&0\\ 0&0&1&1&0&1&0\\ 0&0&1&0&1&0&1\\ 1&0&0&1&0&1&1\\ 0&1&0&0&1&1&1\\ \end{matrix}$

Here is another with period $4$:

$\begin{matrix} 1&1&0&0&0&0&0\\ 1&0&1&1&0&0&0\\ 0&1&1&0&1&0&0\\ 0&1&0&1&0&1&1\\ 1&0&0&0&1&1&0\\ 0&0&0&1&1&1&0\\ \end{matrix}$

and another with period $6$:

$\begin{matrix} 1&1&1&0&0&0&0\\ 1&1&0&1&1&0&0\\ 0&0&1&1&0&1&0\\ 0&0&1&1&0&0&1\\ 1&0&0&0&0&1&1\\ 0&1&0&0&0&1&1\\ \end{matrix}$

On the whole set of $7\times 7$ binary matrices, $\mathcal{L}_J$ gets $$ \begin{array}{r l} 326\,166&\text{fixed matrices}\\ 86\,146\,036&\text{distinct orbits of length }2\\ 94&\text{distinct orbits of length }3\\ 5\,400&\text{distinct orbits of length }4\\ 8&\text{distinct orbits of length }5\\ 196&\text{distinct orbits of length }6\\ \end{array} $$

There are counterexamples for $Q=J$.

Here is a binary $6\times7$ binary matrix $M$ that belongs to an orbit of $L_J$ with period $3$:

$\begin{matrix} 1&1&1&0&0&0&0\\ 1&1&0&1&1&0&0\\ 0&0&1&1&0&1&0\\ 0&0&1&0&1&0&1\\ 1&0&0&1&0&1&1\\ 0&1&0&0&1&1&1\\ \end{matrix}$

Here is another with period $4$:

$\begin{matrix} 1&1&0&0&0&0&0\\ 1&0&1&1&0&0&0\\ 0&1&1&0&1&0&0\\ 0&1&0&1&0&1&1\\ 1&0&0&0&1&1&0\\ 0&0&0&1&1&1&0\\ \end{matrix}$

and another with period $6$:

$\begin{matrix} 1&1&1&0&0&0&0\\ 1&1&0&1&1&0&0\\ 0&0&1&1&0&1&0\\ 0&0&1&1&0&0&1\\ 1&0&0&0&0&1&1\\ 0&1&0&0&0&1&1\\ \end{matrix}$

There are counterexamples for $Q=J$.

Here is a binary $6\times7$ binary matrix $M$ that belongs to an orbit of $\mathcal{L}_J$ with period $3$:

$\begin{matrix} 1&1&1&0&0&0&0\\ 1&1&0&1&1&0&0\\ 0&0&1&1&0&1&0\\ 0&0&1&0&1&0&1\\ 1&0&0&1&0&1&1\\ 0&1&0&0&1&1&1\\ \end{matrix}$

Here is another with period $4$:

$\begin{matrix} 1&1&0&0&0&0&0\\ 1&0&1&1&0&0&0\\ 0&1&1&0&1&0&0\\ 0&1&0&1&0&1&1\\ 1&0&0&0&1&1&0\\ 0&0&0&1&1&1&0\\ \end{matrix}$

and another with period $6$:

$\begin{matrix} 1&1&1&0&0&0&0\\ 1&1&0&1&1&0&0\\ 0&0&1&1&0&1&0\\ 0&0&1&1&0&0&1\\ 1&0&0&0&0&1&1\\ 0&1&0&0&0&1&1\\ \end{matrix}$

On the whole set of $7\times 7$ binary matrices, $\mathcal{L}_J$ gets $$ \begin{array}{r l} 326\,166&\text{fixed matrices}\\ 86\,146\,036&\text{distinct orbits of length }2\\ 94&\text{distinct orbits of length }3\\ 5\,400&\text{distinct orbits of length }4\\ 8&\text{distinct orbits of length }5\\ 196&\text{distinct orbits of length }6\\ \end{array} $$

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There are counterexamples for $Q=J$.

Here is a binary $6\times7$ binary matrix $M$ that belongs to an orbit of $L_J$ with period $3$:

$\begin{matrix} 1&1&1&0&0&0&0\\ 1&1&0&1&1&0&0\\ 0&0&1&1&0&1&0\\ 0&0&1&0&1&0&1\\ 1&0&0&1&0&1&1\\ 0&1&0&0&1&1&1\\ \end{matrix}$

Here is another with period $4$:

$\begin{matrix} 1&1&0&0&0&0&0\\ 1&0&1&1&0&0&0\\ 0&1&1&0&1&0&0\\ 0&1&0&1&0&1&1\\ 1&0&0&0&1&1&0\\ 0&0&0&1&1&1&0\\ \end{matrix}$

and another with period $6$:

$\begin{matrix} 1&1&1&0&0&0&0\\ 1&1&0&1&1&0&0\\ 0&0&1&1&0&1&0\\ 0&0&1&1&0&0&1\\ 1&0&0&0&0&1&1\\ 0&1&0&0&0&1&1\\ \end{matrix}$