Quenched, Annealed and Functional Large Deviations for One-Dimensional Random Walk in Random Environment

Suppose that the integers are assigned random variables f! i g (taking values in the unit interval), which serve as an environment. This environment deenes a random walk fX n g (called a RWRE) which, when at i, moves one step to the right with probability ! i , and one step to the left with probability 1 ? ! i. When the f! i g sequence is i.i.d., Greven and den Hollander (1994) proved a large deviation principle for X n =n, conditional upon the environment, with deterministic rate function. We consider in this paper large deviations, both conditioned on the environment (quenched) and averaged on the environment (annealed), for the RWRE, which forces us to consider also the ergodic environment case. The annealed rate function is the solution of a variational problem involving the quenched rate function and speciic relative entropy. We also give detailed qualitative description of the resulting rate functions. Our techniques diier from those of Greven and den Hollander, and allow us to present also a trajectorial (quenched) large deviation principle.