English

Can each number be specified by a finite text?

Logic 2019-09-26 v1

Abstract

Contrary to popular misconception, the question in the title is far from simple. It involves sets of numbers on the first level, sets of sets of numbers on the second level, and so on, endlessly. The infinite hierarchy of the levels involved distinguishes the concept of "definable number" from such notions as "natural number", "rational number", "algebraic number", "computable number" etc. (Explanatory essay for non-experts.)

Keywords

Cite

@article{arxiv.1909.11149,
  title  = {Can each number be specified by a finite text?},
  author = {Boris Tsirelson},
  journal= {arXiv preprint arXiv:1909.11149},
  year   = {2019}
}

Comments

53 pages. Submitted to WikiJournal of Science: "https://en.wikiversity.org/wiki/WikiJournal_Preprints/Can_each_number_be_specified_by_a_finite_text%3F"

R2 v1 2026-06-23T11:24:47.814Z