work/work and item/item

[kcoyle]

We decided that we would allow iteration of entities, such that a an expression can have a relationship to another expression - expressionA expresses expressionB. (It may make more sense to use: expressionOf) The same is true of manifestation, one manifestation being a manifestation of the other. But we weren't sure how you could have an item of an item, especially with digital copies (#21). Also, we have no predicate for a work that is a work of another work.

See the opening readme.

[kcoyle]

At April 19 meeting we decided that we would NOT define predicates for the entity/entity relationships but would include in the documentation that the possibility is assumed.