10.6 Further comments
- The analysis of the present section exhibits subgroups of the Coxeter group
, with the
property that their Coxeter exponents
(see Section 3) are either 2 or 3, but never
infinity.
Furthermore, the associated Coxeter graphs all have incidence index
, meaning that
each node in the graph is connected to three and only three other nodes. A classification of all
rank 10 and 11 Coxeter groups with these properties has been given in [97].
- Integrability of sigma models for “cosmological billiards” in relation to dimensional reduction
to three dimensions has been extensively investigated in [81, 82, 79, 80, 83].