In this paper, motivated by questions in Harmonic Analysis, we study the operation of (countable) increasing union, and show it is not idempotent: iterations are needed in general to obtain the closure of a class under this operation. Increasing union is a particular Hausdorff operation, and we present the combinatorial tools which allow to study the power of various Hausdorff operations, and of their iterates. Besides countable increasing union, we study in detail a related Hausdorff operation, which preserves compactness.
@article{bwmeta1.element.bwnjournal-article-fmv141i2p169bwm, author = {Sylvain Kahane}, title = {Op\'erations de Hausdorff it\'er\'ees et r\'eunions croissantes de compacts}, journal = {Fundamenta Mathematicae}, volume = {141}, year = {1992}, pages = {169-194}, zbl = {0763.04002}, language = {fra}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-fmv141i2p169bwm} }
Kahane, Sylvain. Opérations de Hausdorff itérées et réunions croissantes de compacts. Fundamenta Mathematicae, Tome 141 (1992) pp. 169-194. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-fmv141i2p169bwm/
[00000] [1] B. Aniszczyk, J. Burzyk and A. Kamiński, Borel and monotone hierarchies and extension of Rényi probability spaces, Colloq. Math. 51 (1987), 11-25. | Zbl 0633.60003
[00001] [2] J. Arbault, Sur l'ensemble de convergence absolue d'une série trigonométrique, Bull. Soc. Math. France 80 (1952), 253-317. | Zbl 0048.04202
[00002] [3] H. Becker, S. Kahane and A. Louveau, Natural complete -sets in Harmonic Analysis, Trans. Amer. Math. Soc., to appear. | Zbl 0799.04006
[00003] [4] G. Choquet, Sur les notions de filtre et de grille, C. R. Acad. Sci. Paris 224 (1947), 171-173. | Zbl 0029.07602
[00004] [5] S. Kahane, Ensembles de convergence absolue, ensembles de Dirichlet faibles et ↑-idéaux, ibid. 310 (1990), 335-337.
[00005] [6] S. Kahane, ↑-idéaux de compacts et applications à l'analyse harmonique, Thèse, Univ. Paris 6, 1990.
[00006] [7] S. Kahane, Antistable classes of thin sets in Harmonic Analysis, Illinois J. Math., to appear. | Zbl 0793.42003
[00007] [8] A. S. Kechris, A. Louveau and W. H. Woodin, The structure of σ-ideals of compact sets,Trans. Amer. Math. Soc. 301 (1987), 263-288. | Zbl 0633.03043
[00008] [9] K. Kuratows, Topology I, Acad. Press, New York 1966.
[00009] [10] H. Lebesgue, Sur les fonctions représentables analytiquement, J. Math. Pures Appl. (6) 1 (1905), 139-216. | Zbl 36.0453.02