5. User interface

The third major part of the system is the user interface. The expert system will present its questions and the user provides the answers.

Quite often the user is given a choice of answers with radio buttons and combo boxes rather than being offered an open ended text box.

This does make it simpler to construct an inference engine based on decision trees because the answers are constrained to a limited set of possibilities. But it does not deal with uncertainty very well.

For example, a computer system help system may present a screen such as the one below

The help system is presenting the user with a set of choices along with navigation buttons.

Complex User interfaces

Some expert systems can deal with more vague answers such as an advanced natural language interface. This 'parses' the speech to extract its meaning. This meaning is then passed to the inference engine.