On the kernel language topic, though, Date and Darwen&#x27;s work [0] on the specifications for an ideal class of database languages unifying OO and Relational models (D; of which Tutorial D is one realization intended principally for pedagogical purposes, hence the name) and their lower level work on an abstract relational algebra (A) to underlie D is probably useful in that regard, as frustrating as some of their work may be to people who just want to get down to using current SQL-based relational DBs.<p>[0] available at <a href="http:&#x2F;&#x2F;www.thethirdmanifesto.com&#x2F;" rel="nofollow">http:&#x2F;&#x2F;www.thethirdmanifesto.com&#x2F;</a>