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Proceedings of the 44th Symposium on Ring Theory and ...

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Next we write <str<strong>on</strong>g>the</str<strong>on</strong>g> Ausl<strong>and</strong>er-Reiten quiver <str<strong>on</strong>g>of</str<strong>on</strong>g> D b (modΓ). In this case, Γ = End A (T ) 0<br />

is isomorphic to 2 × 2 upper triangular matrix algebra over K. We put P 1 := (KK),<br />

P 2 := (0K) <strong>and</strong> I 1 := (K0). It is known that <str<strong>on</strong>g>the</str<strong>on</strong>g> set {P 1 , P 2 , I 1 } is a complete set <str<strong>on</strong>g>of</str<strong>on</strong>g><br />

indecomposable Γ-modules, <strong>and</strong> <str<strong>on</strong>g>the</str<strong>on</strong>g> Ausl<strong>and</strong>er-Reiten quiver <str<strong>on</strong>g>of</str<strong>on</strong>g> D b (modΓ) is as follows.<br />

I 1 [−1] <br />

❄ P 1 P 2 [1] I 1 [1] P 1 [2]<br />

❄<br />

<br />

❄❄❄❄❄<br />

❄ ❄<br />

❄❄❄❄❄<br />

❄<br />

❄❄❄❄❄<br />

❄❄❄❄❄<br />

· · · · · · · · · · · ·<br />

88888<br />

P 1 8<br />

8 88888<br />

[−1] P 2 8<br />

88888<br />

I 1 8<br />

88888<br />

P 1 8<br />

[1] P 2 8<br />

<br />

888888<br />

[2]<br />

Here dotted arrows mean <str<strong>on</strong>g>the</str<strong>on</strong>g> Ausl<strong>and</strong>er-Reiten translati<strong>on</strong> in D b (modΓ).<br />

From shape <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> above Ausl<strong>and</strong>er-Reiten quivers, <strong>on</strong>e can see that mod Z A <strong>and</strong><br />

D b (modΓ) should be equivalent to each o<str<strong>on</strong>g>the</str<strong>on</strong>g>r. In fact, we gave a triangle-equivalence<br />

between those.<br />

References<br />

[1] R. O. Buchweitz, Maximal Cohen-Macaulay modules <strong>and</strong> Tate-cohomology over Gorenstein rings,<br />

preprint.<br />

[2] Xiao-Wu Chen, Graded self-injective algebras ”are” trivial extensi<strong>on</strong>s, J. Algebra 322 (2009), no. 7,<br />

2601–2606.<br />

[3] R. Gord<strong>on</strong> <strong>and</strong> E. L . Green, Graded Artin algebras, J. Algebra 76 (1982), no. 1, 111–137.<br />

[4] , Representati<strong>on</strong> <str<strong>on</strong>g>the</str<strong>on</strong>g>ory <str<strong>on</strong>g>of</str<strong>on</strong>g> graded Artin algebras, J. Algebra 76 (1982), no. 1, 138–152.<br />

[5] D. Happel, Triangulated categories in <str<strong>on</strong>g>the</str<strong>on</strong>g> representati<strong>on</strong> <str<strong>on</strong>g>the</str<strong>on</strong>g>ory <str<strong>on</strong>g>of</str<strong>on</strong>g> finite-dimensi<strong>on</strong>al algebras, L<strong>on</strong>d<strong>on</strong><br />

Ma<str<strong>on</strong>g>the</str<strong>on</strong>g>matical Society Lecture Note Series, 119. Cambridge University Press, Cambridge, 1988.<br />

[6] , Ausl<strong>and</strong>er-Reiten triangles in derived categories <str<strong>on</strong>g>of</str<strong>on</strong>g> finite-dimensi<strong>on</strong>al algebras, Proc. Amer.<br />

Math. Soc. 112 (1991), no. 3, 641–648.<br />

[7] B. Keller, Deriving DG categories, Ann. Sci. Ecole Norm. Sup. (4) 27 (1994), no. 1, 63–102.<br />

[8] B. Keller, D. Vossieck, Sous les catégories dérivées, (French), C. R. Acad. Sci. Paris Sér. I Math. 305<br />

(1987), no. 6, 225–228.<br />

[9] J. Rickard, Derived categories <strong>and</strong> stable equivalence, J. Pure Appl. Algebra 61 (1989), no. 3, 303–317.<br />

Graduate School <str<strong>on</strong>g>of</str<strong>on</strong>g> Ma<str<strong>on</strong>g>the</str<strong>on</strong>g>matics<br />

NagoyaUniversity<br />

Frocho, Chikusaku, Nagoya 464-8602 Japan<br />

E-mail address: m07052d@math.nagoya-u.ac.jp<br />

–255–

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