Open AccessGordon's conjectures 1 and 2: Pontryagin-van Kampen duality in the hyperfinite setting
Author(s) -
Pavol Zlatoš
Publication year - 2021
Publication title -
journal of logic and analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.278
H-Index - 4
ISSN - 1759-9008
DOI - 10.4115/jla.2021.13.1
Subject(s) - mathematics , abelian group , mathematical proof , duality (order theory) , fourier transform , pontryagin's minimum principle , pure mathematics , fourier series , locally compact space , algebra over a field , mathematical analysis , mathematical optimization , geometry , optimal control
Using the ideas of E. I. Gordon we present and farther advancean approach, based on nonstandard analysis, to simultaneousapproximations of locally compact abelian groups and their dualsby (hyper)finite abelian groups, as well as to approximations ofvarious types of Fourier transforms on them by the discrete Fouriertransform. Combining some methods of nonstandard analysis andadditive combinatorics we prove the three Gordon's Conjectureswhich were open since 1991 and are crucial both in the formulationsand proofs of the LCA groups and Fourier transform approximationtheorems