I thought I new matrices pretty well, but you will have to tell me what " " represents. At a guess, I might take it to mean the permutations used in defining the determinant of a matrix:

The determinant of an n by n matrix can be defined as .

Where is a permutation of {1, 2, 3, ..., n}, [tex]sgn(\sigma)[/itex] is 1 if is an even permutation, -1 if it is an odd permutation, and the sum is take over all such permutations.

But that doesn't make sense, nor does your "I know this section falls under determinants", because an "n by m matrix" only has a determinant if m= n.