Uniform three-class regular partial Steiner triple systems with uniform degrees
A Partial Steiner Triple system (X,T) is a finite set of points X and a collection T of 3-element subsets of X that every pair of points intersect in at most 1 triple. A 3-class regular PSTS (written as 3-PSTS([m⋅α,n⋅β,p⋅γ])) is a PSTS where the points can be partitioned into 3 classes (each class having size m, n and p respectively) such that no triple belongs to any class and any two points from the same class occur in the same number of triples (α, β and γ respectively). The 3-PSTS is said to be uniform if m=n=p. In this presentation, I will talk about the existence of uniform 3-PSTS with uniform degrees (α=β=γ).