Relating Small Dynamic Complexity Classes

One of the major goals of descriptive complexity theory is to study the relationship of the expressive power of various logics. The motivation is that results relating the expressive power of logics may help to answer questions like “Is a given query expressible in some logic?” more easily. It may also help to explain why it is hard to express a given query in some logic. Answers to those questions, on the other hand, are highly relevant as they have an immediate impact on the amount of resources necessary to answer a query, due to the close connection between logics and traditional computational complexity classes.