A block design (abbreviated -design) is an incidence structure of points and blocks such that the following hold:
1. There are points,
2. Each block contains points,
3. For any points there are exactly blocks that contain all these points.
A block design (abbreviated -design) is an incidence structure of points and blocks such that the following hold:
1. There are points,
2. Each block contains points,
3. For any points there are exactly blocks that contain all these points.
This entry contributed by Jordan Bell
Bell, Jordan. "t-Design." From MathWorld--A Wolfram Web Resource, created by Eric W. Weisstein. https://mathworld.wolfram.com/t-Design.html