Dear Forum,
I've been using GAP to create incidence matrices of combinatorial
designs. (An incidence matrix M has entries which are 0 and 1 and so the
matrix may be viewed as existing over *any* field.) I would now like to
examine the codes generated by these matrices, that is, I would like to
examine the row space of the matrix M over a field of prime order. I'd
like to find bases for the row space.
How do I do this? A first step, I assume, is to row reduce the
matrix M mod p, but I can't seem to find the right commands.

Thanks in advance,
Ken

Ken W. Smith, Professor of Mathematics, Central Michigan University