P = "in" P = "* of" P = "of *" P = "* *" freq("quart P volume") 4 1 5 19 freq("volume P quart") 10 0 2 16 more weight to columns (patterns) with frequencies that vary substantially from one row (word pair) to the next, and less weight to columns that are uniform.
we weight the cell x i,j by w j = 1 − H j / log(m), which varies from 0 when p i,j is uniform to 1 when entropy is minimal.