English

Constructing a weak subset of a random set

Logic 2019-12-20 v3

Abstract

The tree forcing method given by (Liu 2015) enables the cone avoiding of strong enumeration of a given tree, within a subset or co-subset of an arbitrary given set, provided the given tree does not admit computable strong enumeration. Using this result, we settled and reproduced a series of problems in reverse mathematics. In this paper, we demonstrate cone avoiding results within an infinite subset of a given 1-random set. We show that for any given 1-random set XX, there exists an infinite subset YY of XX such that YY does not compute any real with positive effective Hausdorff dimension, thus answering negatively a question posed by Kjos-Hanssen that whether there exists a 1-random set of which any infinite subset computes some 1-random real. The result is surprising in that the tree forcing technique used on the subset or co-subset seems to heavily rely on subset co-subset combinatorics, whereas this result does not.

Keywords

Cite

@article{arxiv.1602.03690,
  title  = {Constructing a weak subset of a random set},
  author = {Bjørn Kjos-Hanssen and Lu Liu},
  journal= {arXiv preprint arXiv:1602.03690},
  year   = {2019}
}

Comments

10 pages

R2 v1 2026-06-22T12:48:17.163Z