Applying results of the infinitary Ramsey theory, namely the dichotomy principle of Galvin-Prikry, we show that for every sequence of scalars, there exists a subsequence such that either every subsequence of defines a universal series, or no subsequence of defines a universal series. In particular examples we decide which of the two cases holds.
@article{bwmeta1.element.bwnjournal-article-doi-10_4064-ba56-2-1, author = {V. Farmaki and V. Nestoridis}, title = {A Dichotomy Principle for Universal Series}, journal = {Bulletin of the Polish Academy of Sciences. Mathematics}, volume = {56}, year = {2008}, pages = {93-104}, zbl = {1146.05048}, language = {en}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-ba56-2-1} }
V. Farmaki; V. Nestoridis. A Dichotomy Principle for Universal Series. Bulletin of the Polish Academy of Sciences. Mathematics, Tome 56 (2008) pp. 93-104. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-ba56-2-1/