I'm reading a paper on computational geometry and the term pseudodisk popped up. A simple googling doesn't provide me with any mathematical definitions.
Could anyone please explain to me the definition of a pseudodisk?
Edit: For more context: "It has been proved that for geometric objects with finite VC dimension d, there exist $\epsilon$-nets of size $O(\frac{d}{\epsilon}\log\frac{1}{\epsilon})$. $\epsilon$-nets of size $O(\frac{1}{\epsilon})$ exist for halfspaces in $\mathbb{R^2}$ and $\mathbb{R^3}$ and pseudo-disks in $\mathbb{R^2}$." Let me know if this is not enough.
Thanks in advance!
I could find this reference and short explanation, but nothing detailed: "A set of objects is a collection of pseudo-disks, if the boundary of every pair of them intersects at most twice." Chan and Sariel