4.3 Conjunction elimination

This is just the inverse operation of the previous one. It has two parts; firstly:

$$\begin{fitch*} \par n & A \wedge B \\ \par \hline \par & A & E$\wedge$\ n \par \end{fitch*}$$

And secondly, for the case you wanted $B$:

$$\begin{fitch*} \par n & A \wedge B \\ \par \hline \par & B & E$\wedge$\ n \par \end{fitch*}$$

So, you can separate in several lines the conjunctands of a conjunction (yes, I think it's used that strange word). That's why this rule is called conjunction elimination, because from one line which has conjunction symbols ($\wedge$) you can extract several which don't have it, supposedly trying to approach to the formula which we want proved.