3 problems

Total regularity conjecture. All $(r,z,k;-1)$- and $(r,z,k;+1)$-graphs are totally regular.

A graph with defect or excess $2$ is said to have cyclic defect or excess when its defect or excess matrix is the adjacency matrix of a cycle. The Möbius ladder on $8$ vertices is…

Feige's hypergraph Moore bound conjecture. For every $k\ge 3$, there exist constants $c_k,C_k>0$ such that, whenever