Problem 2 from Problem Set 3 read as follows:
Let U be a universe of web pages, web sites, people, and topics. Let L be a first-order language with the following primitives.Use resolution theorem proving to prove (7) from (1-6). Note: It is of course critical that you start with the correct representations. Therefore, if you are uncertain that you found the correct representations, you should hold off starting this problem until the answers to problem set 3 are published on March 29.
S(w,s) --- Predicate. Page w is on site s.
L(w1,w2) -- Predicate. There is a link from page w1 to w2.
A(w,t) --- Predicate. Page w contains information about topic t.
W(p,w) --- Predicate. Person p wrote page w.
R(p,w) --- Predicate. Person p has read page w.
E, F, J, M, T --- Constants representing Elizabeth, frogs, Jim, MySite, and turtles.
Represent the following sentences in L:
- 1. Elizabeth has written a page about turtles.
- 2. All of the pages that Elizabeth has written are on site MySite.
- 3. Every page on MySite has a link to some page that is not on MySite.
- 4. Elizabeth's pages only link to pages about turtles and pages about frogs.
- 5. Jim has written a page that has a link to every page on the web that is either about turtles or frogs.
- 6. Jim has read every page that he has linked to.
- 7. Jim has read some paper outside MySite.