have you downloaded and registered Exsys‘s CORVID expert system software ?

Expert Systems our example a Credit Union – simulating an experienced loan officer processing loan applications

the rules : variables the logic :  "IF …. THEN…"  "SINCE …. I KNEW THAT…"  may involve several conditions that are combined the command : execute the logic

case number loan purpose ability to repay past payment record loan officer's decision 1frivolousgood GRANT 2frivolousgoodslowGRANT 3frivolousgoodpoorDENY 4frivolousbadgoodDENY 5frivolousbadslowDENY 6frivolousbadpoorDENY 7necessitygood GRANT 8necessitygoodslowGRANT 9necessitygoodpoorGRANT 10necessitybadgoodGRANT 11necessitybadslowGRANT 12necessitybadpoorDENY 13luxurygood GRANT 14luxurygoodslowGRANT 15luxurygoodpoorDENY 16luxurybadgoodDENY 17luxurybadslowDENY 18luxurybadpoorDENY The tree diagram makes it easier to see the overall structure of the rules. In CORVID, the logic of a system is built in Logic Blocks which hold the tree diagrams and other logical information. nodes

Ability to Repay Past Payment Record good bad loan purpose GRANT good slow DENY poor GRANT luxury frivolous necessity poor DENY good slow necessity luxury frivolous DENY GRANT nodes

the main CORVID working window please start a new system and save file extension:.cvd

this window provides a wide range of ways to control how a variable is defined, used and asked of the system user.

variables fundamental building blocks for the CORVID expert system three types of variables static list variables numeric variables confidence variables

in our example:static list variables loan purpose ability to repay past payment record

to create a new CORVID variable new variables: name – unique, short, descriptive type – static, numeric, confidence

loan purpose

prompts for the variables : The client’s ability to repay is … The purpose of the loan is … The client’s past payment record is …

bottom right of variables dialogue box repeat for each variable assign values to variables

each variable will have a set of values loan purpose: frivolous necessity luxury ability to repay: bad good past payment record: good slow poor select after entering all values ‘done’‘done’

let’s go ahead and add the loan officer’s decisions as variables these are confidence variables deny grant

main prompt: deny the loan grant the loan deny grant deny the loan

L add a new logic block

examples of logic: IF it is raining THEN wear a raincoat. IF the car will not start AND the gas gage is on empty THEN the car is out of gas. SINCE the light was on I KNEW the computer was getting power. SINCE it is Saturday AND it is sunny I KNEW Fred was probably playing golf.

bottom left: if / and  ‘add’ ‘add to block’ pop-up dialogue box choose a variable  select a value ‘add to list’ ‘done’

for the next node : repeat value selection for the next variable and the last variable

now for the final result, the decision: ‘THEN assignment nodes’ dialogue box

select either grant or deny value to assign to [grant] : [grant] = 100 done

please set up the logic blocks for all the loan officer’s decisions listed on the handout

command block C The Logic Blocks in a system tell it HOW to do something. The Command Blocks tell it WHAT to do and WHEN. control commands operational commands

use a DERIVE command to run the rules and logic

now let’s try to run the expert system

use the properties window icon to change the interface