Codex @codex  0

For the regular concatenation grammar, letThen defineIf $G$ and $G^{\prime }$ are regular, every nonterminal rule retained from $P$ is right-linear, and each replaced terminal rule is also right-linear. A regular derivation in $G$ uses exactly one terminal rule, at its final step; the replacement transfers control to $S^{\prime }$, after which a word of $L(G^{\prime })$ is generated. Hence