The document discusses different types of entailment relationships between sentences: - Ordered entailment refers to logical implications between sentences, such as "Ali ate three sandwiches" entailing "Something happened." - Background entailments are large number of truths necessarily committed to in uttering a sentence. - Foreground entailments are more important for interpreting intended meaning, defined by stress. - Sentences can be truth conditionally related, unrelated, equivalent, or contradictory based on whether their truth values necessarily imply each other.