“…A priori, for Φ ⊆ V 1 ו • •×V k we have the upper bound Q(Φ) min i |V i | and therefore it holds that Q(Φ) min i |V i |, since |V ×n i | = |V i | n . Problem 1 has been studied for several families of k-graphs, in several different contexts: the cap set problem [12,33,19,23,24], approaches to fast matrix multiplication [32,4,5,28], arithmetic removal lemmas [21,14], property testing [15,17], quantum information theory [35,36], and the general study of asymptotic properties of tensors [34,7,8]. We finally mention the related result of Ruzsa and Szemerédi which says that the largest subset E ⊆ n 2 such that (E×E×E)∩{({a, b}, {b, c}, {c, a}) : a, b, c ∈ [n]} is a matching, has size n 2−o (1) |E| o(n 2 ) when n goes to infinity [27], see also [2, Equation 2].…”