Imho an abstraction by itself can be incomplete or unsuitable [0]. If it is neither, it is a good abstraction. I concede that suitability is often hard to quant

Imho an abstraction by itself can be incomplete or unsuitable [0]. If it is neither, it is a good abstraction. I concede that suitability is often hard to quantify. What you describe with algebras, I would label the "precision" [1] of an abstraction. Precise abstractions/algebras require a good specification though and that is often missing in the business domain. [0] http://beza1e1.tuxen.de/leaky_abstractions.html http://beza1e1.tuxen.de/leaky_abstractions.html [1] http://beza1e1.tuxen.de/precise_abstractions.html http://beza1e1.tuxen.de/precise_abstractions.html