Tangles and the Mona Lisa
  We show how an image can, in principle, be described by the tangles of the graph of its pixels.   The tangle-tree theorem provides a nested set of separations that efficiently distinguish all the distinguishable tangles in a graph. This translates to a small data set from which the image can be reconstructed.   The tangle duality theorem says that a graph either has a certain-order tangle or a tree-structure witnessing that this cannot exist. This tells us the maximum resolution at which the image contains meaningful information. 
Reinhard Diestel and Geoff Whittle
math.CO cs.IT math.IT