We prove that the the exponential moments of the position operator stay bounded for the supercritical almost Mathieu operator with Diophantine frequency.

Two different constructions are given of a rank 8 arc-transitive graph with 165 vertices and valency 8, whose automorphism group is M11. One involves 3-subsets of an 11-set while the other involves 4-subsets of a 12-set, and the constructions are linked with the Witt designs on 11, 12 and 24 points. Four different constructions are given of a rank 9 arc-transitive graph with 55 vertices and val...

We show how to use the elements of a sharply k-transitive permutation group of degree n to form error-correcting codes, as suggested by Blake [1], presenting suitable decoding algorithms for these codes. In particular, we concentrate on using the Mathieu group M12 to form a (12,95040,8)-code to correct three errors. The algorithm we give for this code differs from that given by Cohen and Deza [2].