1. Induction: Discussion Sources: –Chapter 3, Lenz et al Book: Case-based Reasoning Technology –www.aic.nrl.navy.mil/~aha/research/applications.html

2. Information Gain Formula Patrons? none X7(-),x11(-) some X1(+),x3(+),x6(+),x8(+) full X4(+),x12(+), x2(-),x5(-),x9(-),x10(-) Gain(A) = I(p/(p+n),n/(p+n)) – Remainder(A) Reminder(A) = p(A,1) I(p 1 /(p 1 + n 1 ), n 1 /(p 1 + n 1 )) + p(A,2) I(p 2 /(p 2 + n 2 ), n 2 /(p 2 + n 2 )) + p(A,3) I(p 3 /(p 3 + n 3 ), n 3 /(p 3 + n 3 )) The standard Expected Value Formula

3. The IDT Example Patrons? none X7(-),x11(-) some X1(+),x3(+),x6(+),x8(+) full X4(+),x12(+), x2(-),x5(-),x9(-),x10(-) Gain(Patrons) = 1 – ((2/12)I(0,1)+(4/12)I(1,0)+(6/12)I(2/6,4/6)) = 0.541

4. The IDT Example (II) Type? french X1(+), x5(-) italian X6(+), x10(-) burger X3(+),x12(+), x7(-),x9(-) X4(+),x12(+) x2(-),x11(-) thai Gain(Type) = 1 – ((2/12)I(1/2,1/2)+(2/12)I(1/2,1/2)+ (4/12)I(2/4,2/4)+(4/12)I(2/4,2/4)) = 0 Thus Parents is a better choice than Type

5. Induction: Fielded Applications 1. Westinghouse: Transforming uranium gas 2. Hartford Steam Boiler: Transformer diagnosis 3. Steel Works Jesenice: Oil/lubricant properties 4. American Express UK: credit cards applicant 5. Siemens (BMT): Equipment configuration 6. USAF school: Thallium diagnosis 7. Boeing (Gold-digger): Manufacturing flaws 8. R.R. Donelly and Sons (APOS): Banding 9. Enichem (Enigma): Trouble shooting motor pumps 10. Palomar Observation (SKICAT): Astronomical cataloging 11. Continuum (Shopping): WWW shopping …

6. Classifying Credit Card Applications (from (Aha, 1996)) Credit card application yes (10% of 10 4 ) Induced Rule System Accept? Borderline? no American Express UK Problem: Expert accuracy was below average (48%) Evaluation: system was iteratively refined with experts 18 attributes (age, years of residence, etc) Improved accuracy: 75%+

7. Reduce Process Delays of Rotogravure Printers Problem: Bandwidth often appears on chrome cylinders causing a shutdown or costly replacement of cylinders. Cause unknown Use of inductive process to predict setting of control parameters (e.g., ink viscosity) Rules were posted on shop floor Gain: less downtime and lower replacement costs

8. Developing Cycle of IDT Applications (Adapted from (Langley, 1995)) Problem formulation Data collection Induction of Decision Trees/rules Evaluation of DT/rules Fielding and acceptance Maintenance

9. When to Consider Decision Trees Examples describable by attribute-value pairs Target function is discrete valued Disjunctive hypothesis might be required Possible noise in data Some functions are not amenable to be represented with decision trees: Parity function (returns true if input has an even number of 1’s)

10. Induction: Advantages Building a decision tree is a straightforward process The information gain measure is built on a sound basis During consultation, only a few tests are necessary before a classification is obtained For industrial applications, the consultation system can be delivered in a runtime system

11. Induction: Limitations DTs are not incremental: cannot be modified in runtime Consultation system is static Handling of unknown values for attributes is problematic The inductive approach cannot distinguish between various classes of users (e.g., experts vs non experts)