There are many mathematical objects that are similar to groups and Cayley graphs of groups but lack homogeneity in some sense. Graphs of webpages with edges corresponding to links are one example. One long-studied example is chess. Some moves have inverses, and others do not. If we create a graph of all positions, it is certainly not homogeneous, and many methods developed for analyzing groups fail miserably (for instance, the graph is finite, so is delta-hyperbolic, but this gives no helpful information).
On the other hand, Morse theory is designed to help one study complex structures by picking out the points of greatest interest, ie the critical points. It has been used in several discrete settings such as video compression to help sort through mounds of intractable data.
My question is, has a version of discrete Morse theory been used to analyze chess? For instance, the critical points would perhaps correspond to positions with a local maximum or minimum number of moves; the absolute minima represent checkmates, the maxima represent positions with a lot of freedom.
Because chess is so well studied, I wonder if this hasn't been studied before. Does anyone know of a reference where Morse-like ideas were used to analyze chess?