Example: Recognizing Five Letters A, B, C, D, E Example features: x: Number of curved segments y: Number of straight segments Where would “F” fall? Suggest an additional feature Straight strokes E B 4 3 2 1 A D Curved strokes C 0 1 2 3   Oct. 2016 Recommender Systems: Sci/Tech

Fingerprint Classification and Matching Needed for criminal investigations and biometric identification Does a fingerprint match any of the prints in a criminal database? Does the fingerprint match one recorded for an authorized user? Ridge Human fingerprints tend to be unique Even identical twins have different prints   Oct. 2016 Recommender Systems: Sci/Tech

Searching the Worldwide Web Google has indexed the entire contents of the Web a b c b b b a b c b a b b c a a b c b a b c b a b c b b 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 a a b 14 a b b 10 a b c 0, 6, 15, 19, 23 b a b 5, 9, 18, 22 b b a 4 b b b 3 b b c 11 b c a 12 b c b 1, 7, 16, 20, 24 c a a 13 c b a 8, 17, 21 c b b 2, 25 Find all occurrences of the pattern “abcbab” a b c 0, 6, 15, 19, 23 b c b 1, 7, 16, 20, 24 c b a 8, 17, 21 b a b 5, 9, 18, 22 Common words are included in the index Uncommon words, or meaningless strings, are indexed by using tuples of letters in the indices a b c 0, 6, 15, 19, 23 b c b 1, 7, 16, 20, 24 c b a 8, 17, 21 b a b 5, 9, 18, 22   Oct. 2016 Recommender Systems: Sci/Tech

Google’s “Pagerank” Algorithm Algorithm to rank the hits so that the most useful ones come first Google also takes your profile, interests, and previous searches into account   Oct. 2016 Recommender Systems: Sci/Tech