We start with a study of the primal-dual affine-scaling algorithms for
linear programs. Using ideas from Kojima et al., Mizuno and Nagasawa,
and new potential functions we establish a framework for primal-dual
algorithms that keep a potential function value fixed. We show that if
the potential function used in the algorithm is compatible with a cor
responding neighborhood of the central path then the convergence proof
s simplify greatly. Our algorithms have the property that all the iter
ates can be kept in a neighborhood of the central path without using a
ny centering in the search directions.