Project/Area Number  06640077 
Research Category 
GrantinAid for Scientific Research (C)

Section  一般 
Research Field 
Algebra

Research Institution  Tokai University 
Principal Investigator 
YAMAGUCHI Masaru Tokai University, School of Science Professor, 理学部, 教授 (10056252)

CoInvestigator(Kenkyūbuntansha) 
WATANABE Junzo Tokai University, School of Science Professor, 理学部, 教授 (40022727)
IZUMISAWA Masataka Tokai University, School of Science Professor, 理学部, 教授 (50108445)
赤松 豊博 東海大学, 理学部, 教授 (00112772)
WATANABE Keiichi Tokai University, School of Science Professor, 理学部, 教授 (10087083)

Project Fiscal Year 
1994 – 1996

Project Status 
Completed(Fiscal Year 1996)

Budget Amount *help 
¥2,100,000 (Direct Cost : ¥2,100,000)
Fiscal Year 1996 : ¥700,000 (Direct Cost : ¥700,000)
Fiscal Year 1995 : ¥700,000 (Direct Cost : ¥700,000)
Fiscal Year 1994 : ¥700,000 (Direct Cost : ¥700,000)

Keywords  Artinian complete intersection / Artinian Gorenstein algebra / general element / Lefschetz condition / onedimensional wave equation / Lissajous boundary condition / Diophantine inequality / quasiperiodic solution / 0次元完全交差環 / 0次元ゴレンスタイン環 / 一般元 / レフシェツ条件 / 一次元波動方程式 / Lissajuus境界条件 / ディオファントス近似不等式 / 準周期解 / O次元完全交差環 / O次元ゴレンスタイン環 / Lissajous境界条件 / 弦の振動 / 1次元波動方程式 / 周期的に動く境界条件 / Diophantine近似 / DenjoyHermanYoccoz理論 / 可換代数 / アルチン環 / ゴレンスタイン環 / Hard Lefschetz / Catalecticant / Hessian / 生成系 
Research Abstract 
I.Behevior of General Elements of Complete Intersections of Height 3 Our main results are stated as follows : Theorem 1. Let R=k [x, y, z] be the polynomial ring over a field k of characteristic 0. Let I be a complete intersection ideal of R generated by homogeneous elements f_1, f_2, f_3 * R of degrees d_1, d_2, d_3 respectively, where we assume that 2<less than or equal>d_1<less than or equal>d_2<less than or equal>d_3. Then the following conditions are equivalent. (i) mu(I+lR/lR)=3 for any general linear form l * R. (ii) d_3<less than or equal>d_1+d_22. Theorem 2. With the same notation and assumption as above we have (i) d_3<less than or equal>d_1+d_22<less than or equal>d_3*I : l is generated by 3 elements. (ii) d_3<less than or equal>d_1+d_22*I : l is generated by 5 elements. As a consequence we can prove that the Hard Lefschetz theorem holds on the the ring R/I for the cases (i) d_1<less than or equal>3, d_2<less than or equal>3, *d_3, (ii) d_1<less than or equal>4, d_2<less than or
… More
equal>4, *d_3*4, (iii) d_3<greater than or equal>d_1+d_23. II.The behavior of the vibrating string with moving boundaries We studied the behavior of the vibrating string with moving boundaries in detail. The most general results are the following. We are dealt with the initialboundary value problem for onedimensional wave equation with timeperiodic boundary conditions and timeperidic boundary functions. This is the mathematical model of the vibrating string with the both ends which describe the Lissajous figures. Every solution is timequasiperiodic if the rotation number of a composed function defined by the boundary functions and the above timeperiods satisfy some Diophantine inequality. From this it follows that for 'almost all' boundary functions the solutions are quasiperiodic. Further the solutions are extended to the spacequasiperiodic functions in the whole R^2plane which satisfy the wave equation and the singularities of the solutions propagate along the reflected characteristics. From our research it is shown that several fundamental properties from the analytic number theory play an essential role in the behavior of the solutions. Less
