Let $\Phi$ be a root system of ADE type, $L$ is the corresponding root lattice, show that $\Phi=\{\alpha\in L:(\alpha,\alpha)=2\}$, where $(,)$ is the normalized non-degenerate symmetric bilinear form
ADE type root lattice
2
$\begingroup$
lie-algebras
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0@JyrkiLahtonen Ok, but maybe not very fast. These days I'm a little busy. – 2012-08-21