Tetrahedron removal lemma

For every $\eta >0$, some $\rho >0$ has this property: a three-uniform hypergraph on $v$ vertices with fewer than $\rho v^4$ copies of the three-uniform tetrahedron can be made tetrahedron-free by removing fewer than $\eta v^3$ hyperedges. The four-term progression hypergraph encoding converts this into the length-four case of the Szemerédi theorem.