I am looking for a word that can be used to describe a system (or a model) with a small number of rules or assumptions. For example, the number of grammatical rules in Japanese is much lower than in Russian.
The meaning I want is close to: concise, succinct or terse, except that these words specifically mean "expressed in few words," while I am looking for something that is more abstract, and describes the low count of assumptions, rules, and statements.
Saying "Japanese is a more concise language than Russian" would mean that ideas can be expressed with fewer words in Japanese than they can in Russian, which is not at all what I want to say.