concept of presupposition in semantics.

In semantics, **presupposition** refers to background assumptions or conditions that are taken for granted in order for a statement to make sense or be meaningful. These assumptions are implicit and must be true for the statement to be properly interpreted. 

For example, the statement "Jane stopped smoking" presupposes that Jane used to smoke. The presupposition here is that Jane was a smoker before she stopped. If the presupposition is false (i.e., if Jane never smoked), the statement may not be interpretable in the expected way.

Presuppositions are crucial for understanding how language conveys information and context, and they often influence how speakers and listeners interpret statements and engage in conversation.