Transactions on Combinatorics (Sep 2013)
On the Nomura algebras of formally self-dual association schemes of class 2
Abstract
In this paper, the type-II matrices on (negative) Latin square graphs are considered and it is proved that, under certain conditions, the Nomura algebras of such type-II matrices are trivial. In addition, we construct type-II matrices on doubly regular tournaments and show that the Nomura algebras of such matrices are also trivial.