set of ideas about ==stricking a balance between together and difference==, is a ==state structure==
==Minimum criteria==: at least __2 levels of gov__, __constitutional design__ = __guaranteed autonomy__ for each level, dividing in national (unity) and subnational (geographically distinct or differenciated) levels
==More criteria== : __written constitution__, __fiscal autonomy__ (constitutional capacity to raise funds aka taxes), __independant judiciary__ (courts to decide which level does what), sometimes more __decentralization__ (how much? not clear)