Erdős asked whether for any n-vertex graph G, the parameter p^* (G) = ₈ ₁ (|V (Gᵢ) |-1) is at most n²/4, where the minimum is taken over all edge decompositions of G into edge-disjoint cliques Gᵢ. In a restricted case (also conjectured independently by Erdős), Győri and Keszegh Combinatorica, 37 (6) (2017), 1113--1124 proved that p^* (G) n²/4 for all K₄-free graphs G. Motivated by their proof approach, they conjectured that for any n-vertex K₄-free graph G with e edges, and any greedy partition P of G of size r, the number of triangles in G is at least r (e-r (n-r) ). If true, this would imply a stronger bound on p^* (G). In this paper, we disprove their conjecture by constructing infinitely many counterexamples with arbitrarily large gap. We further establish a corrected tight lower bound on the number of triangles in such graphs, which would recover the conjectured bound once some small counterexamples we identify are excluded.
He et al. (Mon,) studied this question.
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