En (Lie algebra)

Dynkin diagrams
Finite
E3=A2A1
E4=A4
E5=D5
E6
E7
E8
Affine (Extended)
E9 or E(1)
8
or E+
8
Hyperbolic (Over-extended)
E10 or E(1)^
8
or E++
8
Lorentzian (Very-extended)
E11 or E+++
8
Kac–Moody
E12 or E++++
8
...

In mathematics, especially in Lie theory, En is the Kac–Moody algebra whose Dynkin diagram is a bifurcating graph with three branches of length 1, 2 and k, with k = n − 4.

In some older books and papers, E2 and E4 are used as names for G2 and F4.