Hello millerstI don't know what this bit means.Have you been given an explanation of this? It sounds as if is a binary matrix (all its elements are either or ) but more than that, I can't say....Let Irs be the matrix whose rs-composition is 1...

All I can say for sure so far, is that, if is meaningful, then the number of columns in is the same as the number of rows in . So is a matrix, for some value of , and the order of the resulting product will be .

Can anyone else shed any light on this?

Grandad