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

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symmetric Kac-Moody Lie algebra 14 Lie algebra <br />

Γ Dyn A, D, E <br />

Dynkin case<br />

Definiti<strong>on</strong> 8. Γ = (I, Ω) loop quiver (Z I ) ⊗ Q = Q I <br />

{s(i)|i ∈ I}, bilinear form (·, ·) ( Q I , {s(i)}, (·, ·) ) Dynkin diagram<br />

Γ Dyn root datum (·, ·) Z I bilinear form<br />

Q I <br />

Remark 9. Lie <str<strong>on</strong>g>the</str<strong>on</strong>g>ory root datum <br />

15 Lie<br />

<str<strong>on</strong>g>the</str<strong>on</strong>g>ory root datum Cartan matrix <br />

symmetric quiver<br />

Cartan matrix symmetric Cartan<br />

matrix symmetric <br />

4.2. Crystal .<br />

crystal <br />

crystal <br />

“” <br />

root datum ( Q I , {s(i)}, (·, ·) ) fix {s(i)} Q I <br />

Z-submodule <br />

Q := ⊕ Zs(i)<br />

i∈I<br />

root lattice Q ∼ = Z I P <br />

:<br />

(a) P Q I rank n = |I| Z-submodule <br />

(b) (z, Q) ⊂ Z for every z ∈ P.<br />

(c) s(i) ∈ P for every i ∈ I.<br />

(c) Q ⊂ P <br />

Remark 10. (1) bilinear form (·, ·) Γ A, D, E <br />

(a), (b), (c) can<strong>on</strong>ical <br />

P <br />

P := {z ∈ Q I | (z, Q) ⊂ Z}<br />

lattice Q dual lattice <br />

<br />

(·, ·) Γ extended Dynkin <br />

P Z (a) <br />

can<strong>on</strong>ical P choice <br />

14 symmetric A(Γ Dyn ) Kac-Moody<br />

Lie algebra Cartan matrix <br />

15 Lie <str<strong>on</strong>g>the</str<strong>on</strong>g>ory <br />

–175–

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