where the sum is taken over the set BS(λ,ρ 1) of border strips within the Young diagram of shape λ that have ρ 1 boxes and whose removal leaves a valid Young diagram. The notation λ λ ∖ ∖ ξ ξ represents the partition that results from removing the border strip ξ from λ. The notation ρ ρ ∖ ∖ ρ ρ 1 represents the partition that results from removing the first element ρ 1 from ρ.