Exercise 4 (Homework 4).
(context-free languages,
ambiguity,
union,
concatenation,
reverse,
Kleene star,
homomorphism)
Context-free closure operations and ambiguity
Given unambiguous context-free grammars G_1 and G_2,
- could the construction to obtain the grammar for the union G_1\cup G_2 give an ambiguous grammar?
- could the construction to obtain the grammar for the concatenation G_1\cdot G_2 give an ambiguous grammar?
- could the construction to obtain the grammar for the Kleene star G_1^* give an ambiguous grammar?
- could the construction to obtain the grammar for the reverse G_1^R give an ambiguous grammar?
- given also a homomorphism \sigma, could the construction to obtain the grammar for \sigma(G_1) give an ambiguous grammar?