Formalization of some facts about activities

	The problem arises in connection with Doug Lenat's
discussion of selecting a computer for Fred's Exxon station.
The question is whether and when facts about activities and
equipment that facilitates them have to be formalized in a
different way than other requirements.  Down to a certain
level of detail it may be that the distinction isn't
necessary.

	We have the following facts, which we will give
in English for the time being.

1. A service station business needs a service station.

2. A service station needs a building.  A building
needs a roof.  The building must be suitable for
a service station.

3. A business needs selling.

4. Selling needs recording sales.

5. Recording sales is facilitated by having a computer.

	Up to this point it appears that the English grammar
of the sentences justifying a roof and the grammar
of the sentences justifying recording sales are
sufficiently similar.  Of course, as soon as we want
to talk about individual sales events, we would expect
large differences in what's true.

	Before we get to individual sales events, we
may need to consider beginning and ending activities.
For example, Fred may decide that he will need a computer
only when he starts selling diesel fuel and truck supplies
next August.  Beginning and ending activities presumably
has different formal properties from discrete events
like installing a computer or a roof.