  Two-stage optimization with recourse model is an important and widely used
model, which has been studied extensively these years. In this article, we will
look at a new variant of it, called the two-stage optimization with recourse
and revocation model. This new model differs from the traditional one in that
one is allowed to revoke some of his earlier decisions and withdraw part of the
earlier costs, which is not unlikely in many real applications, and is
therefore considered to be more realistic under many situations. We will adopt
several approaches to study this model. In fact, we will develop an LP rounding
scheme for some cover problems and show that they can be solved using this
scheme and an adaptation of the rounding approach for the deterministic
counterpart, provided the polynomial scenario assumption. Stochastic
uncapacitated facility location problem will also be studied to show that the
approximation algorithm that worked for the two-stage with recourse model
worked for this model as well. In addition, we will use other methods to study
the model.
