New posts in Combinatorial Designs

How many combinations of groups are there where no member of a group has been with another member before?

"Math Lotto" Tickets - finding the minimum winning set

Getting everyone to meet everyone else

Is there a memorable solution to Kirkman's School Girl Problem?

What are efficient pooling designs for RT-PCR tests?

Lower bound for a combinatorial problem ($N$ students taking $n$ exams)

Pfaffian representation of the Fermat quintic

Minimum covers of complete graphs by $4$-cycles

Fano plane drawings: embedding PG(2,2) into the real plane

Linear algebra proofs in combinatorics?