Definite Clause Grammar Parser

Using Prolog, this project implements a parser for a simple definite clause grammar of English-Light. English-Light is a fragment of English (i.e., English-Light does not include any ungrammatical English sentences), which accounts for structures as those appearing in the following examples.

1. The young boy pushed and stored a big box in the large empty room after school.
2. The old woman and the old man gave the poor young man a white envelope in the shed behind the building.
3. Every boy quickly climbed some big tree and every girl watched some boy whom she liked.
4. Some brilliant students and many professors watched and admired talented lecturers and appreciated bright scientists and researchers.
5. Who climbed the big tree?
6. What did professors do?