We provide a survey of interior-point methods for linear programming a
nd its extensions that are based on reducing a suitable potential func
tion at each iteration. We give a fairly complete overview of potentia
l-reduction methods for linear programming, focusing on the possibilit
y of taking long steps and the properties of the barrier function that
are necessary for the analysis. We then describe briefly how the meth
ods and results can be extended to certain convex programming problems
, following the approach of Nesterov and Todd. We conclude with some o
pen problems.