460-hw1sol

460-hw1sol - CS4600 - Introduction to Intelligent Systems...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
CS4600 - Introduction to Intelligent Systems Homework 1 - Decision Trees - Sample Solution Assume that you have the following training examples available: Use all of the training examples to construct a decision tree. In case of ties between features, break ties in favor of features with smaller numbers (for example, favor F1 over F2, F2 over F3, and so on). How does the resulting decision tree classify the following example: F1 F2 F3 F4 F5 Class Example 1 t t f f f p Example 2 f f t t f p Example 3 t f f t f p Example 4 t f t f t p Example 5 f t f f f n Example 6 t t f t t n Example 7 f tttt n F1 F2 F3 F4 F5 Class Example 8 f f f t t ?
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Some formula: Pre-compute some I(x,y) I(0,x) = I(x,0) = -1 log 2 1 - 0 log 2 0 = 0 I(x,x) = - 1/2 log 2 1/2 - 1/2 log 2 1/2 = 1 I(1,2) = I(2,1) = - 2/3 log 2 2/3 - 1/3 log 2 1/3 = 0.918 I(1,3) = I(3,1) = - 3/4 log 2 3/4 - 1/4 log 2 1/4 = 0.811 I(3,4) = I(4,3) = - 4/7 log 2 4/7 - 3/7 log 2 3/7 = 0.985 First, choose from {F1, F2, F3, F4, F5} to become the root. E(F1) = 4/7 * I(3,1) + 3/7 * I(1,2) = 4/7 * 0.811 + 3/7 * 0.918 = 0.857 E(F2) = 4/7 * I(1,3) + 3/7 * I(3,0) = 4/7 * 0.811 + 3/7 * 0 = 0.463 E(F3) = 3/7 * I(2,1) + 4/7 * I(2,2) = 3/7 * 0.918 + 4/7 * 1 = 0.965
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 09/10/2008 for the course CS 460 taught by Professor Svenkoenig during the Fall '08 term at Urbana.

Page1 / 4

460-hw1sol - CS4600 - Introduction to Intelligent Systems...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online