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Is there a $3$-uniform hypergraph on $n$ vertices which contains at least $n-O(1)$ different sizes of cliques (maximal complete subgraphs)
Erdős constructed such a hypergraph with cliques of at least $n-\log_*n$ different sizes. For graphs, Spencer [Sp71] constructed a graph which contains cliques of at least $n-\log_2n+O(1)$ different sizes, which Moon and Moser [MoMo65] showed to be best possible.

The answer is no, as proved by Gao [Ga25]: more generally, for any $k\geq 3$, every $k$-uniform hypergraph on $n$ vertices contains at most $n-f_k(n)$ different sizes of cliques, where $f_k(n)\to \infty$ as $n\to \infty$.

See also [927].

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This page was last edited 17 October 2025.

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When referring to this problem, please use the original sources of Erdős. If you wish to acknowledge this website, the recommended citation format is:

T. F. Bloom, Erdős Problem #775, https://www.erdosproblems.com/775, accessed 2026-01-16