LaTeX disjoint union

Symbol Command
$A \sqcup B$ A \sqcup B
$A \uplus B$ A \uplus B
$A \dot\cup B$ A \dot\cup B

Big square cup

Symbol Command
$\bigsqcup A_i$ \bigsqcup A_i
$\bigsqcup_{i \in I} A_i$ \bigsqcup_{i \in I} A_i
$\displaystyle{\bigsqcup A_i}$ \displaystyle{\bigsqcup A_i}
$\displaystyle{\bigsqcup_{i \in I} A_i}$ \displaystyle{\bigsqcup_{i \in I} A_i}

Big u plus

Symbol Command
$\biguplus A_i$ \biguplus A_i
$\biguplus_{i \in I} A_i$ \biguplus_{i \in I} A_i
$\displaystyle{\biguplus A_i}$ \displaystyle{\biguplus A_i}
$\displaystyle{\biguplus_{i \in I} A_i}$ \displaystyle{\biguplus_{i \in I} A_i}

LaTeX set

LaTeX