Limit cubic laminations

Let $\sigma_3:\mathbb{S}\to \mathbb{S}$ be the tripling map of the unit circle.

For sequences $\{\mathcal{L}_i\}$ of $\sigma_3$-invariant dendritic laminations we study limits $(\overline{c}, \overline{d})$ of their critical portraits assuming that one such limit $\mathcal{P}=(\overline{c}_\circ, \overline{d}_\circ)$ is given.

If the endpoints of $\overline{c}_\circ$ and $\overline{d}_\circ$ are non-periodic, then there is a unique lamination $\mathcal{L}$ with finite critical sets such that $\overline{c}$ and $\overline{d}$ can be any couple of critical chords compatible with $\mathcal{L}$.

As the extreme opposite case we consider $\mathcal{P}=(\overline{0 \frac13}, \overline{0 \frac23})$ and describe the corresponding countable closed family of possible critical portraits $(\overline{c}, \overline{d})$ and the distinct laminations corresponding to them.

These results can be useful for the construction of a model for the cubic connectedness locus.