Let $k$ be an algebraically closed field of characteristic zero. Define
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\begin{align*}
\Phi: \{\text{isomorphism classes of finite-dimensional simple Lie algebras over } k\} &\to \{\text{connected finite type Dynkin diagrams}\} \\
[\mathfrak g] &\mapsto \Delta(\mathfrak g),
\end{align*}
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where $\Delta(\mathfrak g)$ is the Dynkin diagram of the root system of $\mathfrak g$. Then $\Phi$ is a bijection. The connected finite type Dynkin diagrams are precisely