2003 Fiscal Year Final Research Report Summary
Research on explicit construction of worst imputs for algorithms
| Project/Area Number |
13680426
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
計算機科学
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| Research Institution | Soka University |
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Principal Investigator |
KOBAYASHI Kojiro Soka University, Dept. of Eng., Prof., 工学部, 教授 (00016148)
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| Project Period (FY) |
2001 – 2003
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| Keywords | worst input / worst computation time / heapsort / Burrows-Wheeler transform / block sorting |
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| Research Abstract |
1. Explicit construction of worst inputs for Heapsort
We explicitly constructed a class of worst inputs for Heapsort by the following steps : (1)the explicit construction of some of the worst inputs for phase 2, (2)the analysis of the transformation realized by phase 1, (3)the explicit construction of some of the worst inputs for phase 1, (4)the proof that there exist worst inputs for phase 1 constructed in (3)that are transformed into worst inputs for phase 2 constructed in (1)by the transforamtion of phase 1.
2. Analysis of the structures in the inputs to block sorting
Block sorting is a part of the Burrows-Wheeler transformation that is used in several recent data compression algorithms. An input to block sorting is the sequence of sequences that are circular shifts of the sequence to be compressed. Such sequences have some structures in themselves and it is possible to design a fast sorting algorithm that utilized these structures. We analyzed the numbers of inversions and the runs in the inputs to block sorting for compressing randomly generated sequences.
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