  We present the extention and application of a new unsupervised statistical
learning technique--the Partition Decoupling Method--to gene expression data.
Because it has the ability to reveal non-linear and non-convex geometries
present in the data, the PDM is an improvement over typical gene expression
analysis algorithms, permitting a multi-gene analysis that can reveal
phenotypic differences even when the individual genes do not exhibit
differential expression. Here, we apply the PDM to publicly-available gene
expression data sets, and demonstrate that we are able to identify cell types
and treatments with higher accuracy than is obtained through other approaches.
By applying it in a pathway-by-pathway fashion, we demonstrate how the PDM may
be used to find sets of mechanistically-related genes that discriminate
phenotypes.

Quantitative Methods;Genomics;Molecular Networks;Computation;Machine Learning