We are given two well-formed formulas (wffs) $[\mathbf{B} \vee \mathbf{C}]$ and $[\mathbf{D} \vee \mathbf{E}]$, and we need to show that if these two wffs are the same, then $\mathbf{B}$ must be $\mathbf{D}$ and $\mathbf{C}$ must be $\mathbf{E}$.
Show more…