English

Statistically p-Upward Quasi-Cauchy Sequences and Cone-Valued Continuity

General Topology 2026-02-17 v1

Abstract

We introduce statistically pp-upward quasi-Cauchy sequences, defined by the condition limn1n{kn:xkxk+pε}=0\lim_{n\to\infty}\frac{1}{n}|\{k\leq n: x_k - x_{k+p}\geq\varepsilon\}|=0 for every ε>0\varepsilon>0, and develop the corresponding notions of compactness and continuity. We prove that a subset of R\mathbb{R} is statistically pp-upward compact if and only if it is bounded below, characterizing lower boundedness sequentially. Statistically pp-upward continuity is shown to imply uniform continuity on below bounded sets. The function space SUCp(E)\mathrm{SUC}_p(E) is a closed convex cone that fails to be a vector subspace -- distinguishing it from all previously studied sequential continuity spaces. We establish that every non-decreasing uniformly continuous function belongs to SUCp(E)\mathrm{SUC}_p(E), use Weyl's equidistribution theorem to show sinxSUCp(R)\sin x\notin\mathrm{SUC}_p(\mathbb{R}), prove a step-parameter hierarchy, and show that SUCp(E)Cb(E)\mathrm{SUC}_p(E)\cap C_b(E) is nowhere dense in Cb(E)C_b(E). As an application, we develop a one-sided error control theory for function approximation, illustrated by Bernstein operators on a pharmacokinetic model. The inclusion relations among the continuity types studied and open problems are provided.

Keywords

Cite

@article{arxiv.2602.14125,
  title  = {Statistically p-Upward Quasi-Cauchy Sequences and Cone-Valued Continuity},
  author = {Açıkgöz.},
  journal= {arXiv preprint arXiv:2602.14125},
  year   = {2026}
}

Comments

25 pages, 26 references

R2 v1 2026-07-01T10:37:29.331Z