The fixed-point partition lattices
The fixed-point partition lattices
Let σ be a permutation of the set {1,2, ..., n} and let [Pi](N) denote the lattice of partitions of {1,2, ..., n}. There is an obvious induced action of σ on [Pi](N); let [Pi](N)σ = L denote the lattice of partitions fixed by σ.