  We study critical hysteresis in the random-field Ising model (RFIM) on a
two-dimensional periodic lattice with a variable coordination number $z_{eff}$
in the range $3 \le z_{eff} \le 6$. We find that the model supports critical
behavior in the range $4 < z_{eff} \le 6$, but the critical exponents are
independent of $z_{eff}$. The result is discussed in the context of the
universality of nonequilibrium critical phenomena and extant results in the
field.
