Open AccessCompounding Objects
Author(s) -
Zvonimir Šikić
Publication year - 2020
Publication title -
bulletin of the section of logic
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.225
H-Index - 13
eISSN - 2449-836X
pISSN - 0138-0680
DOI - 10.18778/0138-0680.2020.10
Subject(s) - converse , compounding , intuition , mathematics , simple (philosophy) , characterization (materials science) , pure mathematics , calculus (dental) , discrete mathematics , physics , philosophy , geometry , epistemology , medicine , nursing , dentistry , optics
We prove a characterization theorem for filters, proper filters and ultrafilters which is a kind of converse of Łoś's theorem. It is more natural than the usual intuition of these terms as large sets of coordinates, which is actually unconvincing in the case of ultrafilters. As a bonus, we get a very simple proof of Łoś's theorem.