Balanced incomplete block design

2020 Mathematics Subject Classification: Primary: 05B05 [MSN][ZBL]

BIBD

A block design on a set of points and blocks (sets of points) which is "balanced": each block is of the same size, each point appears in the same number of blocks and each pair of points occurs in the same number of blocks; and "incomplete", not in general the complete collection of sets of given size. Equivalently, a $2$-design.

See Block design for further details and references.