Implementing SQL ASSERTION

Hi all,

I’m wondering if there are other people out there working on implementing SQL ASSERTION functionality?

I’ve recently spent a bit of time looking to implement the execution models described in “Applied Mathematics for
DatabaseProfessionals” by Toon Koppelaars and Lex de Haan.  I’ve gotten as far as execution model 3 and am now looking
atderiving polarity of involved tables to do EM4 (described in some detail in “Deriving Production Rules for Constraint
Maintenance”,Ceri & Widom, VLDB Conference 1990, p555-577). EM5 & EM6 look rather more difficult but I’m intending to
tryand implement those, too. 

If there are other people working on this stuff it would be great to collaborate.

Regards.
-Joe