Frank Ruskey recently pointed out to us that an earlier construction and proof of the existence of balanced Gray codes for all n, attributed to T. Bakos, appears in the book Truth functions and the problem of their realization by two-terminal graphs, by A. Ádám, Akadémiai Kiadó, Budapest, 1968. This predates even the Robinson-Cohn paper. It also contains a proof of the question resolved by Kedlaya in the 1997 comment.

October 22, 2005
Carla Savage
North Carolina State University
savage@cayley.csc.ncsu.edu