Logic and Inference: Rules Từ một quan điểm trừu tượng, các đối tượng của các chương trước đó liên quan đến đại diện của kiến thức: kiến thức về nội dung của các tài nguyên Web, và kiến thức về các khái niệm về một lĩnh vực diễn thuyết và các mối quan hệ của họ (ontology). Đại diện kiến thức đã được nghiên cứu rất lâu trước khi sự xuất hiện của World Wide Web, trong lĩnh vực trí tuệ nhân tạo, trước đó, trong triết học. Trong thực tế, nó có thể được truy trở lại Hy Lạp. | TLFeBOOK 5 . Logic and Inference Rules Introduction From an abstract viewpoint the subjects of the previous chapters were related to the representation of knowledge knowledge about the content of Web resources and knowledge about the concepts of a domain of discourse and their relationships ontology . Knowledge representation had been studied long before the emergence of the World Wide Web in the area of artificial intelligence and before that in philosophy. In fact it can be traced back to ancient Greece Aristotle is considered to be the father of logic. Logic is still the foundation of knowledge representation particularly in the form of predicate logic also known as first-order logic . Here we list a few reasons for the popularity and importance of logic It provides a high-level language in which knowledge can be expressed in a transparent way. And it has a high expressive power. It has a well-understood formal semantics which assigns an unambiguous meaning to logical statements. There is precise notion of logical consequence which determines whether a statement follows semantically from a set of other statements premises . In fact the primary original motivation of logic was the study of objective laws of logical consequence. There exist proof systems that can automatically derive statements syntactically from a set of premises. There exist proof systems for which semantic logical consequence coincides with syntactic derivation within the proof system. Proof systems TLFeBOOK TLFeBOOK 152 5 Logic and Inference Rules should be sound all derived statements follow semantically from the premises and complete all logical consequences of the premises can be derived in the proof system . Predicate logic is unique in the sense that sound and complete proof systems do exist. More expressive logics higher-order logics do not have such proof systems. Because of the existence of proof systems it is possible to trace the proof that leads to a logical consequence. In this
