Vidwan - An Expert System Shell
The expert systems approach has been used to solve a wide variety of hard- t o -solve problems. MYCIN, XCON and COMPASS are examples of systems which use this approach to solve some real world problems. Expert systems approach attempts to model the domain knowledge of human experts in their respective areas of specialisation, for example, diagnosis, planning, forecasting, etc., where real expertise is hard to come by. Most of these areas are characterised by the fact that only uncertain and incomplete information is available to take decisions. Often the number of factors affecting the decision is large. Hence, an algorithmic approach to tackle these problems is usually difficult. The expert systems approach lessens the complexities of solving these problems by making the domain knowledge more explicit. An expert system has a rulebase and an inference engine as its essential components. The rulebase contains the domain knowledge. The inference engine provides the control strategy for reasoning with the rule-base. Programs consisting of such inference engines and associated user interface, explanation facilities, etc. are called expert system shells. Use of shells make it easy to develop expert systems in different domains, by developing only the rule-base for the domain.
About Vidwan
Vidwan is a web based expert system shell which allows creation of rule based expert systems, by encoding expert's knowledge as a set of rules. If - Then rules is supported as the basic paradigm for representing domain knowledge in the rulebase. Rules in Vidwan have their antecedents and consequents dealing with attribute - value tuples. The antecedent provides for the testing and comparison of the values of an attribute. The consequent provides for the setting of a value to an attribute.
Vidwan supports a backward chaining inference engine with uncertainty handling similar to the MYCIN system. Vidwan supports explanation facilities like why (Why do you want to know that?) show rule (Show me a particular rule), how (How did you get the value(s) for a particular attribute?) and show attributes (Tell me what values you have got for a particular attribute).
The rulebase can be created using any text editor. The system also provides an Interactive Editor facility that can be used to manipulate the knowledge in the knowledge bases and allows you to create a new knowledge base from scratch.
The use of menus and templates for attributes are supported. This can be used to make questions to the user sufficiently detailed and comprehensive. A limited arithmetic capability is also provided. Vidwan provides a friendly user interface and on - line help to provide help to the users for understanding the various features in the system and how to use them.
Saving and loading responses: The user can save the responses given during a session in a file and load them during another run. This enables using standard stored test responses for debugging a rulebase. This facility is also useful for continuing an earlier consulting session with revised data.
Another useful feature is the ` revoke' option. This option allows the user to review the responses he had given so far in the current run. This facility can be requested any time a question is posed to the user by Vidwan. When the system walks through the list of at tributes and values one by one, the user can selectively clear the values that an attribute has been set to.
A knowledge base verification facility has been provided so as to check the stored knowledge against redundant rules, conflicting rules, circular rules, subsumed rules etc.
A built - in report generator facility is provided to design application dependant layouts for display of conclusions as well as for generating detailed reports of consultation sessions.
Prototypes have been developed on Vidwan for a large variety of applications including medical advisors (eg., cardiology, respiratory diseases, rheumatism, etc), troubleshooting systems (electric motor, electronic equipments, printer, etc) and financial advisors (credit worthiness, share investment, taxplanning, etc).
Availability
The web based beta version of Vidwan is now available for use. You can access it directly at
http://www.cdacmumbai.in/vidwan
. A help link accessible through the homepage of vidwan can aid you better understand the system and how to use it.
You can run the system using the sample rulebases stored in the system and for creating your own rulebases you can mail us at kbcs[at]cdacmumbai.in.
Though Vidwan is available for use on the web, for commercial usage and for any assistance you can write to us through mail or contact us at:
CDAC,Mumbai (Kharghar)
(Formerly NCST)
Raintree Marg, Near Bharati Vidyapeeth,
Opp. Kharghar Railway Station,
Sector 7, CBD Belapur,
Navi Mumbai 400614, India.
Telephone: + 91-22-27565303 Telefax: + 91-22-27560004
