Pragmatics plays animportant role in correctly understanding sentences. Much usefulinformation will be lost if the context in which a sentence isasserted is ignored. There are some approaches in logic topragmatics, such as situation theories and context logics.Although these methods associate a sentence with a context or asituation, they consider only the truth value of the sentence.However, a sentence should have more meanings than its truthvalue, and people care more about what a sentence conveys. For theaffection of contexts, the meaning of a sentence is not always itssemantic meaning and a sentence may have different pragmaticalimplications in different contexts. In this paper, a context isconsidered as some structure in the real world. A sentence fromsome logical language is conceptualized as a concept, whose intentis a set of sentences implied semantically by the sentence, and whoseextent is a set of contexts in which the sentence describes a part of the contexts. In terms of tools and theories of concepts, astrictly defined theory is given to study the pragmatics ofsentences in contexts in information systems, which cannot bederived from the sentences by using logical reasoning methods.

Key words: Term rewriting system; constructor system; head boundedness;