Definition:Block Incidence Matrix of a Design

Definition
The block incidence matrix of a $\tuple {v, b, r, k, \lambda}$-BIBD, is a $v \times b$ incidence matrix $A = \sqbrk {a_{ij} }$ such that:


 * $a_{ij} = \begin {cases}

1 & : \text {if the $i$th point is in the $j$th block} \\ 0 & : \text {otherwise} \end {cases}$