Ah, that is what you mean. Then the answer is that they are used for different things. PEGs are typically used to parse a string, while regexps are typically u

Ah, that is what you mean. Then the answer is that they are used for different things. PEGs are typically used to parse a string, while regexps are typically used to recognize a pattern. Where regexps are used for parsing, then ambiguity is definitely a problem that very often will have to be resolved by rewriting the regexp to be less accepting.