%0 Journal Article %T Fractal percolation, porosity, and dimension %A Changhao Chen %A Tuomo Ojala %A Eino Rossi %A Ville Suomala %J Mathematics %D 2015 %I arXiv %X We study the porosity properties of fractal percolation sets $E\subset\mathbb{R}^d$. Among other things, for all $0<\varepsilon<\tfrac12$, we obtain dimension bounds for the set of exceptional points where the upper porosity of $E$ is less than $\tfrac12-\varepsilon$, or the lower porosity is larger than $\varepsilon$. Our method works also for inhomogeneous fractal percolation and more general random sets whose offspring distribution gives rise to a Galton-Watson process. %U http://arxiv.org/abs/1508.05244v1