Grammar with same variables If a grammar has the same variable multiple times, is it the same as adding a $\mid$ between them? For example, is

$$\begin{align*}S &amp;\to bB  \\
S &amp;\to \varepsilon  \\
B &amp;\to cB  \\
B &amp;\to \varepsilon  \end{align*}$$

equal to the following?

$$\begin{align*}S &amp;\to bB \mid \varepsilon \\ 
B &amp;\to cB \mid \varepsilon \\
\end{align*}$$
Yes. (you are right, the "$\mid$" sign is a classical notation for the alternative rules for a variable.)