Are Articles and demonstrative mutually exclusive?

No, articles and demonstratives are not mutually exclusive; they can be used together in a sentence. An article provides information about the noun's definiteness, while a demonstrative specifies which particular noun is being referred to. For example, in the phrase "the this book," "the" is the article and "this" is the demonstrative. However, it's worth noting that such combinations are rare in natural language use.