3.6 Projections

Consider now the problem of agreement between noun and relative pronoun: they must agree in gender and number, but nothing else. How can we express such agreement condition, when gender and number have been combined with other features into one DomainProduct? What we need is to project a DomainProduct onto a subset of its dimensions. In this section, we illustrate how this can be achieved using the selection constraint.

The idea is that to each tuple [G N P C Q] in the cartesian product:

Gender * Number * Person * Case * Quantifier

we can associate a corresponding tuple [G N] in the projection product Gender * Number. In other words, there is a finite map from the integers encoding the 1st product into the integers encoding the 2nd product.

Denys Duchier
Version 1.2.0 (20010221)