Problem Set 4

Assigned: Mar. 22.
Due: Apr. 5.

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.

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:

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.