> ... if the variance is low ... Yes, thats a better way of putting it. The variance is so low that the tree always ended up very deep. I put a lot of effort

> ... if the variance is low ... Yes, thats a better way of putting it. The variance is so low that the tree always ended up very deep. I put a lot of effort into tuning bucket sizes etc but in the end it just didn't work out. > ... you could represent you formulae as trees instead of strings ... For some definitions of edit distance, the edit distance between two trees is equivalent to the Levenshtein distance between the in-order traversals of the trees. In any case, the tree structure of LaTeX itself tends to be quite flat and non-useful and the the tree structure of the equations themselves is hard to derive in general. ArXMLiv is working on this, among others, but its still a hard research problem. If I could get my hands on the tree structure I would be doing more sophisticated searches than edit distance, cf hoogle and uniquation.