# Tag Info

Use & to separate the state from its explanation, and use \text to denote text mode. $\sigma(x) = \begin{cases} 1 & \text{if$\sum_{k=1}^{n} x_{k} > \theta$and$i = 0$}\\ 0 & \text{otherwise} \end{cases}$ Syntactically, if $\sum_{k=1}^{n} x_{k} > \theta$ and $i = 0$ is a sentence, albeit a sentence that contains two formulas.