| Project/Area Number |
15540146
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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 |
General mathematics (including Probability theory/Statistical mathematics)
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| Research Institution | Oita University (2005)
Fukushima National College of Technology (2003-2004) |
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Principal Investigator |
SUETAKE Chihiro Oita University, Faculty of Engineering, Professor, 工学部, 教授 (80353241)
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| Project Period (FY) |
2003 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥2,500,000 (Direct Cost: ¥2,500,000)
Fiscal Year 2005: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2004: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2003: ¥1,000,000 (Direct Cost: ¥1,000,000)
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| Keywords | finite projective plane / automorphism group / orthogonal array / finite geometry / incidence structure / incidence matrix / transversal design / symmetric transversal design / 有数幾何学 |
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| Research Abstract |
We got the following four results.
(1)It was proved that there is no projective plane of order 12 admitting a collineation group of order 16 by showing the nonexistence of some orthogonal array OA (72,12,6,2). We used a computer for our research.
(2)It was proved that there is only one symmetric transversal design STD_4[12;3] up to isomorphism. We also showed that the order of the full automorphism group of STD_4[12;3] is 2^5・3^3 and Aut STD_4[12;3] has a regular subgroup as a permutation group on the point set. We used a computer for our research.
(3)We constructed a symmetric transversal sesign STD_7[21;3] admitting an automorphism group of order 7 which acts semiregularly on the set of the point groups and on the set of block groups.
(4)Let S be a blocking semioval in arbitrary projective plane Pi of order 9 which meets some line in 8 points. According to Dover in [2], 20leqvert Svertleq 24. In [7] one of the authors showed that if Pi is desarguesian, then 22leqvert Svertleq 24. In this note all blocking semiovals with this property in all non-desarguesian projective plane of order 9 are completely determined. In any non-desarguesian plane Pi it is shown that 21leqvert Svertleq 24 and for each iin{21,22,23,24} there exist blocking semiovals of size I which meet some line in 8 points. Therefore, the Dover's bound is not sharp.
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