Uniform, rigid branchwise-real tree orders

Sam Adam-Day

Published 2022-06-30Version 1

A branchwise-real tree order is a partial order tree in which every branch is isomorphic to a real interval. I give constructions of such trees which are both rigid (i.e. without non-trivial order-automorphisms) and uniform (in two different senses). Specifically, I show that there is a rigid branchwise-real tree order in which every branching point has the same degree, one in which every point is branching and of the same degree, and finally one in which every point is branching of the same degree and which admits no order-preserving function into the reals. Trees are grown iteratively in stages, and a key technique is the construction (in $\mathrm{ZFC}$) of a family of colourings of $(0,\infty)$ which is `sufficiently generic', using these colourings to determine how to proceed with the construction.