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# Tag Archives: Higman

## Terminology: association scheme or coherent configuration?

At the Villanova conference, many of the talks were about association schemes or coherent configurations, or indeed generalisations of these. A certain tension between different uses of these terms was evident. I’d like to set down my own views here. … Continue reading

Posted in exposition, history
Tagged association scheme, Bose, coherent configuration, Higman, Leman, Mesner, Nair, Schur ring, Shimamoto, Terwilliger, Weisfeiler
2 Comments

## The Graph Extension Theorem

I made some notes on the Graph Extension Theorem for a new research project. They may be of wider interest, so here is a summary. Shult’s Graph Extension Theorem is a simple device for showing that certain permutation groups have … Continue reading

Posted in exposition
Tagged Higman, Seidel, Shult, switching, transitive extension, two-graph
4 Comments