In
mathematics
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, especially in
Lie
A lie is an assertion that is believed to be false, typically used with the purpose of deceiving or misleading someone. The practice of communicating lies is called lying. A person who communicates a lie may be termed a liar. Lies can be inter ...
theory, E
''n'' 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, ''E''
2 and ''E''
4 are used as names for
''G''2 and
''F''4.
Finite-dimensional Lie algebras
The E
''n'' group is similar to the A
''n'' group, except the nth node is connected to the 3rd node. So the
Cartan matrix appears similar, -1 above and below the diagonal, except for the last row and column, have −1 in the third row and column. The determinant of the Cartan matrix for E
''n'' is 9 − ''n''.
*E
3 is another name for the Lie algebra ''A''
1''A''
2 of dimension 11, with Cartan determinant 6.
*: