Approach to the density ideal by density of special testing sets on the real line
It is known that a set A ⊂ ℕ belongs to the density ideal $$\mathcal{Z}$$ if and only if zero is a dispersion point of a specific interval subset of ℝ defined for the sequence 1/n, namely, of the set $${\bigcup }_{i\in A}\left[1/\left(i+1\right),1/i\right].$$ We investigate here for which decreasing sequences (xn) tending to zero the analogous equivalence holds, that is, for which sequences A ∈ $$\mathcal{Z}$$ if and only if zero is a dispersion point of $${\bigcup }_{i\in A}\left[{x}_{i+1},{x}_{i}\right].$$
Authors
- Tomasz Filipczak (ORCID: https://orcid.org/0000-0001-8067-6585)
- Gražyna Horbaczewska (ORCID: https://orcid.org/0000-0002-2883-0941)
- Małgorzata Filipczak (ORCID: https://orcid.org/0000-0002-1137-9648)
Institutions
- Lodz University of Technology (PL)
- University of Łódź (PL)
Publication Details
- Journal
- Lithuanian Mathematical Journal
- Published
- 2025-10-01
- DOI
- https://doi.org/10.1007/s10986-025-09696-w
- Primary Topic
- Approximation Theory and Sequence Spaces
- Type
- article
- Field-Weighted Citation Impact
- 0.00