This was the book that taught me the difference between "facts", "rules" and "queries" in Prolog, which was the terminology I had been taught at my university P

This was the book that taught me the difference between "facts", "rules" and "queries" in Prolog, which was the terminology I had been taught at my university Prolog course. The difference being: there is no difference. They are all Horn clauses, the "queries" are Horn goals and the "facts" and "rules" are definite program clauses. I was enlightened. The NLP stuff -Definite Clause Grammars- is also interesting, in the sense that it's surprising that a notation that can be used to parse language (definite clauses) can also be used to represent any program a Universal Turing Machine can compute.