deletions | additions       diff --git a/Readings.tex b/Readings.tex  index bb43b0b..6b2dc32 100644  --- a/Readings.tex  +++ b/Readings.tex 
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Miscellaneous stuff.  \begin{itemize}  \item Renormalisation group good for things with structure, where correlations between sites are important. Could be good for CLUSTERING investigation, especially if I can write down a Hamiltonian for the whole system composed of other particles (will certainly have to simplify this a lot!).  \item In Langevin analysis (e.g. \citet{http://adsabs.harvard.edu/abs/1975JFM....72..499H}) we define inertia and friction tensors $\mathbf{m}$ and $\mathbf\zeta$, which act on the system's state vector $\mathbf x$. What does it mean when these are symmetrical? When they are diagonal?  \end{itemize}