set symbols

I was about to pick up an algorithm book to read ... "Computational Geometry", and found out that there is some gap that I am missing.......

I don't understand the symbols of the formula in the book.

After some search thru the Internet, got to know that those are actually called the "symbol set".

and here is a very good site that explains it

http://www.rapidtables.com/math/symbols/Set_Symbols.htm

https://www.glenoaks.edu/facultystaff/FacultyWebSites/JillToner/Documents/NSM105%20-%20Math%20for%20El%20Ed/Section%202.1%20-%20Set%20Theory.pdf

http://castle.eiu.edu/~mathcs/mat2120/index/set03-2x3.pdf

Here is the cheat sheet from one of the above pdf file:-