: [ S \to aSa \mid bSb \mid a \mid b \mid \varepsilon ]
Derivation for abba : [ S \Rightarrow aSbS \Rightarrow a\varepsilon bS \Rightarrow abS \Rightarrow abbSaS \Rightarrow abb\varepsilon a\varepsilon = abba ] Language : Valid arithmetic expressions with a, b, +, *, (, ) cfg solved examples
: [ E \to E + T \mid T ] [ T \to T \times F \mid F ] [ F \to (E) \mid a \mid b ] : [ S \to aSa \mid bSb \mid