A list of sequences of elements can be represented by a prefix tree exploiting similar or equal prefixes and subprefixes of each single sequence in the list. If each element in a sequence also belongs to some part of a hierarchy, i.e. all elements contained in all sequences can be hierarchically organized, a Trees in a Treemap representation can be used to visualize this kind of data.
A sophisticated layout algorithm produces the Trees in a Treemap by following several parameters: edge lengths, number of edge bends, and distances between neighbored routes. The layout algorithm has a high runtime complexity when allowing more than three edge bends for one sequence and when routes become very long. The layout algorithm tries to find a layout where as little route crossings as possible are produced.
If you are interested in the Trees in a Treemap approach please read our paper that we presented at the Conference on Visualization and Data Analysis in San Jose, California in 2006 or write an email.