Functional structure

Expert system is characterized by a specific functional structure whose basic elements are:

• Knowledgebase - provides the knowledge needed to solve the problem, called domain knowledge
• User Interface - allows the user to communicate with the requesting system and knowledge base editor

In addition to these basic elements, an expert system has auxiliary elements, which include:

• Dynamic database - used to store the user's response and the results of inference
• Editor knowledge base - used for reading, formulate and modify the knowledge base

An important feature expert system is that the knowledge base was a text file written in a clear and transparent manner. This file can be created, read and modified with an editor knowledge base, without compromising the integrity of the requesting system which is an executable file.

Source: http://home.agh.edu.pl/~pmarynow/index3.html

As you can see in the picture above, you can communicate with a base of knowledge only through the user interface and editor of the knowledge base (for editing the knowledge base), or through the user interface and the system the applicant (to request). With a dynamic knowledge base system only contacted by the requesting system, introducing to it the facts declared by the user or the facts resulting from reasonings.