This exercise concerns the relationships between event categories and the time intervals in which they occur,

a. Define the predicate T(c, i) in terms of during and Є.

b. Explain precisely why we do not need two different notations to describe conjunctive event categories.

c. Give a formal definition for T (One Of (p. q), i) and T (Either (p, q), i).

d. Explain why it makes sense to have two forms of negation of events, analogous to the two forms of disjunction. Call them not and never and give them formal definitions.