Symbols:T

Set

$T$

Used to denote a general set, often in conjunction with $S$ when more than one set is under discussion.

The $\LaTeX$ code for $T$ is T.

Algebraic Substructure

$T$

Used to denote a general algebraic substructure, of the algebraic structure $S$, in particular a subsemigroup.

In this context, frequently seen in the compound symbol $\left({T, \circ}\right)$ where $\circ$ represents an arbitrary binary operation.

The $\LaTeX$ code for $\left({T, \circ}\right)$ is \left({T, \circ}\right).