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X/O Grid
Posted:
Dec 19, 2012 1:32 AM


Consider an n by m grid of x's and o's.
An xpath from the bottom squares of the grid to the top squares of the grid considitues a seqence of horizontally or vertically adjacent xsquares from some bottom xsquare to some top xsquare. Similar with opaths.
An exit is a top square that is connected to a bottom square by either an xpath or an opath. For example, in the 8 by 3, x/o grid
x x o o x x o o x x o o x o x x x x o o x x x o x o x
has two oexits and three xexits for a total of five exits.
In an n by m, x/o grid, what is the expected number of exits?



