# Wrong Tits-Index of E7 from Springer 's book

In the his book

Linear algebraic groups, by T.A. Springer,

there is a list of possible Tits-Indexes. For the $E_7$ case, there is an index shown, such that vertex $1$ and $7$ are circled (Bourbaki notation). I just realized that yesterday by coincidence. However in Tits's original paper this index is not listed. On top of that neither here

http://arxiv.org/pdf/1511.02538.pdf

nor here

http://arxiv.org/abs/0807.2140

do we find it.

What did go wrong in Springers book?

• There must be lots of disappointed people coming here from the Hot Network Questions list. *cough* Jun 30, 2016 at 16:35
• I didnt intend to troll. Changed the title.
– nxir
Jun 30, 2016 at 18:15

That is a typo. In index 14 on p. 321 the vertex 6 should be black. In Proposition 17.8.2, this index is correct. It corresponds to $E_{7,3}^{28}$ in Tits' notation.