Chains of Cantor subspaces of Mahler T-Numbers and the middle-third Cantor set
Sidney A. Morris
Electronic Research Archive ›› 2025, Vol. 33 ›› Issue (12) : 7277 -7288.
We investigate Mahler’s real T-numbers through Cantor-type constructions inside $\mathcal{T} \cap \mathbb{G}$, where G is the middle-third Cantor set and $\mathcal{T}$ is the set of real Mahler T-numbers. We build explicit families $\mathcal{T}$(t) which are homeomorphic to Cantor space and use them to analyze structural, combinatorial, and additive properties of $\mathcal{T}$ . Our results include the existence of descending chains of Cantor subsets of $\mathcal{T}$ of length c; a characterization of ternary expansions in $\mathcal{T}$(t), showing non- normality but maximal block complexity under sparse forcing, linked to the Adamczewski–Bugeaud criterion; and a sumset theorem proving that for suitable parameters t1, t2 one has the interval identity $\mathcal{T}$(t1) + $\mathcal{T}$(t2) = [0, 1], which yields the global corollary $\mathcal{T}$ + $\mathcal{T}$ = $\mathbb{R}$ (Erd˝os property) by integer translation invariance. We also discuss implications for cardinal invariants and entropy of the shift map, highlighting the interplay between thin Diophantine sets and large additive structure. To address a natural concern about existence, we include a non-emptiness lemma which shows that our scheduled deletion-and-witness procedure always leaves a non-empty perfect set $\mathcal{T}$ (t).
Mahler T-numbers / Cantor set / descending chain / cardinality / Erd˝os property
| [1] |
|
| [2] |
|
| [3] |
|
| [4] |
|
/
| 〈 |
|
〉 |