\small
\xymatrix{
	\cdots \ar[r] & H_{i+1}(E^{k+1}, E^k) \ar[r] \ar[d]^\iso & H_i(E^k, F) \ar[r] \ar[d] & H_i(E^{k+1}, F) \ar[r] \ar[d] & \cdots \\
	\cdots \ar[r] & H_{i+1}(B^{k+1}, B^k) \ar[r] & H_i(B^k, b_0) \ar[r] & H_i(B^{k+1}, b_0) \ar[r] & \cdots
}
