Sets & logic

A set is a well-defined collection of distinct objects, called elements. A set is well-defined if it is possible to determine clearly whether any given object belongs to it. Sets are usually labeled with capital letters. Elements are listed inside curly braces \(\{ \}\), separated by commas. An ellipsis \(...\) shows that a pattern continues. The symbol \(\in\) means "is an element of," while \(\notin\) means "is not an element of." The empty set, containing no elements, is written \(\{\}\) or \(\emptyset\).