The sum number of d-partite complete hypergraphs

A d-uniform hypergraph H is a sum hypergraph iff there is a finite S ⊆ IN such that H is isomorphic to the hypergraph H+d (S) = (V, E), where V = S and E = {{v1, . . . , vd} : (i 6= j ⇒ vi 6= vj)∧ ∑d i=1 vi ∈ S}. For an arbitrary d-uniform hypergraph H the sum number σ = σ(H) is defined to be the minimum number of isolated vertices w1, . . . , wσ 6∈ V such that H ∪ {w1, . . . , wσ} is a sum hypergraph. In this paper, we prove σ(K n1,...,nd) = 1 + d ∑ i=1 (ni − 1) + min {