This article comments on an ongoing investigation,
the prediction of RNA secondary structure using stochastic
methods, in particular stochastic context-free grammars. While
the investigation in this field has already made a lot of progress
and is currently refining and improving its methods, this article
is meant to provide an introduction to this subject for researchers
in the digital signal processing area. After situating the problem
in its biological context, we explain the basics of transformational
grammars, which are used to model the RNA secondary
structure. Then we present the three basic problems for these
structures, and explain the three main algorithms to solve them,
relating these to the analogous algorithms for hidden Markov
models