dkubb/axiom — pull request #38 by dkubb (2013-07-26 08:12:36+00:00)
Title: Relation variables

This branch will add a relation variable that will wrap a relation and propagate writes then update its reference to use the new relation.

* [x] Refactor Relation::Empty
* [x] Add Relation::Variable
* [ ] Update axiom-optimizer to work with Relation::Variable
* [ ] Ready for review