Set Theory

Sets are one of the most fundamental building blocks in mathematics. Set Theory is the study of sets of objects, and the relationships between them. For example, $$ \{1,2,3\} $$ is the set of the numbers $1$, $2$, and $3$. The curly braces $\{\}$ are used to denote a set, and the elements of the set are listed inside, separated by commas. And while we did put numbers in this set, we could’ve put anything we wanted, like symbols: $$ \{\lambda,\star,\square,\Sigma\} $$