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Unformatted text preview: Homework1 Solutions Question 1
1. Compute the decision tree generated by ﬁrst considering WRITABLE, then UPDATED, then SIZE. 2. What tree is generated by using ID3? Starting with s = {1, 2, 3, 4, 5, 6}, we have: Entropy (s) Entropy (sW RIT ABLE ) Entropy (sU P DAT ED) Entropy (sSIZE ) = 1.0 = 0.9183 = 0.54 = 0.7925 Gain(sW RIT ABLE ) Gain(sU P DAT ED) Gain(sSIZE ) = = = 0.0817 0.46 0.2075 Therefore, the best choice is UPDATED. This produces the following partition: s1 = {2, 3}, we have Entropy (s1 ) Entropy (s2 ) Entropy (s2 SIZE ) Entropy (s2 W RIT ABLE ) = = = = 0 0.811 0 0.5 s2 = {1, 4, 5, 6} Gain(s2 SIZE ) = Gain(s2 W RIT ABLE ) = 0.811 0.311 Therefore, the best choice is SIZE. 3. How would these trees classify the following two instances: Tree 1: 1 — text 2 —exe Tree 2: 1 — text 2 — text ...
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 Spring '09
 Dr.mohammednizari

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