  We have used Dynamic Monte Carlo (DMC) methods and analytical techniques to
analyze Single-File Systems for which diffusion is infinitely-fast. We have
simplified the Master Equation removing the fast reactions and we have
introduced a DMC algorithm for infinitely-fast diffusion. The DMC method for
fast diffusion give similar results as the standard DMC with high diffusion
rates. We have investigated the influence of characteristic parameters, such as
pipe length, adsorption, desorption and conversion rate constants on the
steady-state properties of Single-File Systems with a reaction, looking at
cases when all the sites are reactive and when only some of them are reactive.
We find that the effect of fast diffusion on single-file properties of the
system is absent even when diffusion is infinitely-fast. Diffusion is not
important in these systems. Smaller systems are less reactive and the occupancy
profiles for infinitely-long systems show an exponential behavior.
