CoInvestigator(Kenkyūbuntansha) 
TOKUHIRO Tokuhiro (KITAMURA,TOKUHIRO) Tokyo Gakugei University, Department of Mathematics, Professor, 教育学部, 教授 (00014811)
KURANO Kazuhiko Tokyo Metropolitan University, Department of Mathematics, Associate Professor, 理学部, 助教授 (90205122)
蔵野 和彦 東京都立大学, 理学部, 助教授 (90205188)

Budget Amount *help 
¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2001: ¥1,100,000 (Direct Cost: ¥1,100,000)

Research Abstract 
First, we study Picard groups and derived Picard groups of finite dimensional hereditary algebras. We obtain general results on the structure of Picard groups and derived Picard groups, as well as explicit calculations for the Dynkin and affine quivers, and for some wild quivers with multiple arrows. In addition we prove that when A is hereditary, the derived Picard group of A coincides with the full group of Minear triangle autoequivalences of the derived category of A. Hence we can calculate the group of noncommutative projective spaces introduced by KontsevichRoseriberg.Second, we show that a compact object C in a triangulated category, which satisfies suitable conditions, induces a tstructure. Third, in an abelian category we show that a complex P of small projective objects of term length two, which satisfies suitable conditions, induces a torsion theory. In the case of module categories, using a torsion theory, we give equivalent conditions for P' to be a tilting complex. Finally, in the case of artin algebras, we give a one to one correspondence between tilting complexes of term length two and torsion theories with certain conditions. Moreover, We have the following related results : 1) First, we define test modules to calculate Dutta multiplicities and study the relation. Second, we characterize Roberts rings by some Galois extensions. Third, it is shown that a Chow group A.(A) of A is determined by cycles and a rational equivalence with respect to certain Ggraded ideals of a Noetherian ring that graded by a finitely generated Abelian group G.Finally,we prove that the induced map G_0(A) → G_0(A) by completion is injective if A is an excellent Noetherian local ring that satisfies one of the three conditions (K. Kurano). 2) It is shown that for a quasiFrobenius extension A of a right nonsingular ring B if A is a right selfinjective ring, then so is B (Y. Kitamura).
