写作COMP6714程序语言、辅导data编程、写作Python，Java程序

” 写作COMP6714程序语言、辅导data编程、写作Python，Java程序COMP6714 ASSIGNMENT 1DUE ON 20:59 4 NOV, 2020 (WED)Q1. (25 marks)Some Boolean retrieval systems (e.g., Westlaw) support the proximity operator /S, whichrestricts the occurrences matches to be within the same sentence.Assume that we have Created an additional positional list for $, which records the positionsof the end of the sentences. E.g., for the documentA B C. D E.the position list for $ is [4, 7].You are required to engine an algorithm to support the query A /S B. To make the taskeasier, we further constrain the semantics of the query to satisfy both conditions: the occurrences of A and B must be within the same sentence. the occurrence of A must precede that of B.For example, the above example document matches the query A /S C, but not C /S A.You need to make simple modifications to the pseudocode shown in Algorithm 1, which is exactlythe algorithm in Figure 2.12 in the textbook. Note that we modify thealgorithm slightly So that array indexes start from 1 instead of 0. Specifically, you need to insert some code between Lines 6 and 7, and perform some modificationsto some lines afterwards. In your submitted algorithm pseudocode (named Q1(p1, p2, p$)), clearly markthe modifications using color or boxes. You can assume that there is a function skipTo(p, docID, pos), which move thecursor of list p to the first position such that (1) the position belongs to a documentdocID, and (2) the Position is no smaller than pos.Q2. (25 marks)Consider the scenario of dynamic inverted index construction. Assume that t sub-indexes(each of M pages) will be created if one chooses the no-merge strategy.(1) Show that if the logarithmic merge strategy is used, it will result in at most dlog2tesub-indexes.(2) Prove that the total I/O cost of the logarithmic merge is O(t M log2t).12 DUE ON 20:59 4 NOV, 2020 (WED)Algorithm 1: PositionalIntersect(p1, p2, k)1 answer ;2 while p1 6= nil p2 6= nil do3 if docID(p1) = docID(p2) then4 l [ ];5 pp1 positions(p1); pp2 positions(p2);6 while pp1 6= nil do7 while pp2 6= nil do8 if |pos(pp1) pos(pp2)| k then9 add(l, pos(pp2));10 else11 if pos(pp2) pos(pp1) then12 break;13 pp2 next(pp2);14 while l 6= [ ] |l[1] pos(pp1)| k do15 delete(l[1]);16 for each ps l do17 answer answer [docID(p1), pos(pp1), ps];18 pp1 next(pp1);19 p1 next(p1); p2 next(p2);20 else21 if docID(p1) docID(p2) then22 p1 next(p1);23 else24 p2 next(p2);25 return answer ;Q3. (25 marks)After the Encoding, the compressed non-positional inverted list is01000101 11110001 01110000 00110000 11110110 11011 Decode the sequence of numbers the compressed list represents. List the document IDs in this list.Q4. (25 marks)Consider the WAND algorithm described in Section 2.4 in the original paper.1. Thereis a typo in the algorithm in Line 21: it should use terms[0 .. (pTerm-1)].1Efficient Query Evaluation using a Two-Level Retrieval Process.COMP6714 ASSIGNMENT 1 3However, even with this fixed, there is a bug in the algorithm (Figure 2) in which thealgorithm will end up in an infinite loop.You need to Identify the single lines in Figure 2 that causes the bug and describe concisely whythis will lead to a bug. Give a simple example illustrating this bug. You should use three terms (namedA, B, C) and k = 1. Do not include unncessary entries in the lists.A B CUBListh1, 3i h1, 4i h1, 4iSubmission InstructionsYou need to write your solutions to the questions in a pdf file named ass1.pdf. Youmust include your name and student ID in the file, and the file can be opened correctly on CSE machines.You need to show the key steps to get the full mark.Note: Collaboration is allowed. However, each person must independently write uphis/her own solution.You can then submit the file by give cs6714 ass1 ass1.pdf. The file size is limitedto 5MB.Late Penalty: -10% per day for the first two days, and -20% per day for the followingdays.如有需要，请加QQ：99515681 或邮箱：99515681@qq.com

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