46 Chapter 2 Knowledge-Based systems arChiteCture
system themselves. If necessary, a sensory interface and knowledge update fa-
cility is provided; it can serve as a general-purpose framework for the knowl-
edge-based system.
Various knowledge-based system development tools are available. They
differ in the level of flexibility they provide in the system and in the range of
knowledge representation, reasoning, and other intelligent techniques they
support. They also differ in the interoperability level and systems users can
develop using those tools. The shell comprises the inference and explana-
tion facilities of a knowledge-based system, without the domain-specific
knowledge. This is beneficial to nonprogrammers, who can include ...