Abstract
We investigate differences between upper and lower porosity. In finite dimensional Banach spaces every upper porous set is directionally upper porous. We show the situation is very different for lower porous sets; there exists a lower porous set in \(\mathbb{R}^2\) which is not even a countable union of directionally lower porous sets.
Citation
Gareth Speight. "Directional Lower Porosity." Real Anal. Exchange 39 (1) 45 - 56, 2013/2014.
Information
