The uses of ``and''

Consider this knowledge base, which expresses some facts about various under- and post-graduates.

Write, in Prolog, the sentences below. Explain the different meanings of ``and'' in each.

• Dave and Jason are third-years.

• Dave and Jason are friends.

• The JCR Warden's duties are mending the pinball machine and the video-games and selling punt cards.

• First-years, second-years, and third-years are undergraduates and members of the JCR.