Local-global conjecture for the semigroup orbit of Ψ1\Psi_1

Define

Ψ1:=(1111),(1011)+.\Psi_1:=\left\langle\begin{pmatrix}1&1\\1&1\end{pmatrix},\begin{pmatrix}1&0\\1&1\end{pmatrix}\right\rangle^+.

The table of congruence and reciprocity obstructions specifies the stated restrictions on numerators and denominators in these orbits. Local-global conjecture for Ψ1\Psi_1. The table completely characterizes the numbers that can appear as numerators or denominators in orbits of Ψ1\Psi_1; equivalently, every sufficiently large integer not ruled out by the given congruence and reciprocity obstructions appears in the orbit. This is supported by computational evidence in the paper, while a proof is not known.

Sources & referencesView supporting material

Primary source

James Rickards and Katherine E. Stange, “Reciprocity obstructions in semigroup orbits in SL(2, Z)”, arXiv:2401.01860 (2025).

Progress summary

Never refreshed

Nothing recorded yet. Refresh searches the literature and the public web for attempts on this problem, and writes the first summary here.

Solutions 0

No solutions have been posted yet.