Miroslav Zelen\'y
Sets of extended uniqueness and $\sigma $-porosity

Comment.Math.Univ.Carolinae 38,2 (1997) 337-341.

Abstract:We show that there exists a closed non-$\sigma $-porous set of extended uniqueness. We also give a new proof of Lyons' theorem, which shows that the class of $H^{(n)}$-sets is not large in $U_0$.

Keywords: $\sigma $-porosity, sets of extended uniqueness, trigonometric series, $H^{(n)}$-sets
AMS Subject Classification: Primary 42A63