Right order spectral gap estimates for generating sets of ℤ4

Using coupling arguments, a distance method and Zeifman's method we give sharp estimates on the spectral gap for a special case of the class of Markov chains on generating n‐tuples of Abelian groups. In our case the group is ?₄. © 2002 Wiley Periodicals, Inc. Random Struct. Alg. 20: 220–238, 2002