Relational algebra is agreed upon. SQL is loosely based on it. On the other hand, there's not even a single agreed upon notion for objects. There's a rigorou

Relational algebra is agreed upon. SQL is loosely based on it. On the other hand, there's not even a single agreed upon notion for objects. There's a rigorous notion of a .NET object but it's not compatible with Java's, C++'s, Smalltalk's, ...