1. Figure 2. showed a very simple taxonomic tree for animals. Using a dictionary or encyclopędia if needed, try extending the tree to include `platypus', `iguana', and `zebra'. What special problem is posed by trying to create a node for `platypus' in the hierarchy? How might this be overcome? (Hint: Look again at the treatment of `ostrich' in this chapter.)
  2. In the second section of this chapter's appendix, we have shown how semantic networks can be represented as database facts, and we have represented facts about Tweetie the Canary in this form. Complete the representation of the isa-hierarchy in Figure2. with facts about Percy the Platypus, Iggy the Iguana, and Ziggy the Zebra.
  3. At the beginning of this tutorial we gave examples of syllogisms, and in Figure 4. we showed how the set-theoretic interpretation of birds and canaries could be represented diagrammatically with circles. We might regard such a diagrammatic representation as a `model' of facts given in syllogistic form. Draw similar diagrams to prove that the conclusions in the syllogisms below do not logically follow from the premises.
    (a) Premiss 1:
    Premiss 2:
    Anyone who studies AI is clever
    Jessica is clever
    Jessica studies AI
    (b) Premiss 1:
    Premiss 2:
    No vegetarians eat meat
    Layla doesn't eat meat
    Layla is a vegetarian
  4. [@to be completed]
  5. [@to be completed]