32语言和文法 L1={wew|w∈(ab) S→>aSa|bSb|c L2={ memon|n≥1,m≥1 S→>aSda4d A→ bAc bc L2"={m" bcmd|n≥1,m≥1 S→AB A→4bmb B→>CBd|cd3.2 语言和文法 • L1 = {wcwR | w(a|b) * } S → aSa | bSb | c • L2  = {a nb mc md n | n  1, m  1} S → aSd | aAd A → bAc | bc • L 2  = {a nb nc md m | n  1，m  1} S → AB A → aAb | ab B → cBd | cd