 Let us say that some clause in a complex sentence is redundant relative to some context of utterance if you can replace that clause by a tautology without affecting the amount of factual information conveyed by the sentence in that context. For example, in (28), the first conjunct is redundant in any context of utterance. Here, the same factual information would be conveyed by “Mary is Mary and Mary owns a sheep”, where the first conjunct is replaced by the tautology “Mary is Mary”.