Permutation groups, partition lattices and block structures

Marina Anagnostopoulou-Merkouri, R. A. Bailey, Peter J. Cameron

Let $G$ be a transitive permutation group on $\hat{I}\text{c◯}$. The $G$-invariant partitions form a sublattice of the lattice of all partitions of $\hat{I}\text{c◯}$, having the further property that all its…