设有文法G[S]: S→S(S)S|ε，该文法是否为二义文法？

该文法不是二义文法。二义文法是指存在至少两个不同的推导序列可以生成同一个句子的文法。对于给定的文法G[S]: S→S(S)S|ε，可以通过推导来证明它是无二义的。

首先，我们可以推导出句子S，如下所示：
S → S(S)S → ε(S)ε → (S)。

然后，我们可以再次推导出句子S，如下所示：
S → S(S)S → S(S(S)S)S → (S(S)S)(S)S → (ε(S)ε(S)ε)(S)S → (ε(S)ε)(S)S → (ε(S)ε)(ε(S)ε)(S)S → (ε(S)ε)(ε(S)ε)(ε(S)ε)(S)S → (ε(S)ε)(ε(S)ε)(ε(S)ε)(ε(S)ε)(S)S → (ε(S)ε)(ε(S)ε)(ε(S)ε)(ε(S)ε)(ε(S)ε)(S)S → (ε(S)ε)(ε(S)ε)(ε(S)ε)(ε(S)ε)(ε(S)ε)(ε(S)ε)(S)S → ... → (ε(S)ε)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)()(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(...)(