We review the latest advances in the analytical modelling of single file diffusion. We focus first on the derivation of the fractional Langevin equation that describes the motion of a tagged file particle. We then propose an alternative derivation of the very same stochastic equation by starting from the diffusion-noise formalism for the time evolution of the file density.
Special Issue Comments: This article presents mathematical formulations and results on the dynamics in files with applied potential, yet also general files. This article is connected to the Special Issue articles about the zig zag phenomenon,72 advanced statistical properties in single file dynamics,73 and expanding files.74