ps1 - CS 276a Problem Set #1 Assigned: Tuesday, October 5,...

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CS 276a Problem Set #1 Assigned: Tuesday, October 5, 2004 Due: Thursday, October 14, 2004 by 5:30 p.m. Review session: Friday, October 8, 2004, 3:15-4:05 p.m. in Gates B01 Delivery: Local students should hand their solutions to Louis in class or leave them in the box by Professor Manning’s office. SCPD students should use the SCPD courier system. Late policy: Refer to the course webpage. Honor code: Please review the collaboration and honor code policy on the course webpage. Also note: because some questions may be drawn from previous years’ problem sets or exams, students are forbidden to consult solution sets from previous years unless we explicitly provide them . 7 questions and 70 points total. #1. Integer coding (5 points) Identify the set of all positive integers (show each integer using decimal, unary, and gamma coding) that: a. have smaller length using unary coding than using gamma coding. (A correct specification of the set is sufficient for this part.) b. have the same length using unary coding and using gamma coding. Prove that no integer outside your set has this property. #2. Positional indexing (10 points) Consider the following fragment of a positional index with the format word: document: position, position … document: position … Gates: 1:3 2:6 3:2,17 4:1 IBM: 4:3 7:14 Microsoft: 1:1 2:1,21 3:3 5:16,22,51 The NEAR/x operator in text retrieval has the following syntax: Word1 NEAR/x 1
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Word2 finds occurrences of Word1 within x words of Word2, where x is a positive integer argument. Thus x = 1 demands that Word1 be adjacent to Word2 (but not necessarily in that order). a. Describe the set of documents that satisfy the query
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ps1 - CS 276a Problem Set #1 Assigned: Tuesday, October 5,...

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