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Suyun Jiang (江素云), How connectivity affects the extremal number of trees

Tuesday, May 30, 2023 @ 4:30 PM - 5:30 PM KST

Room B332, IBS (기초과학연구원)


Suyun Jiang (江素云)
Jianghan University

The Erdős-Sós conjecture states that the maximum number of edges in an $n$-vertex graph without a given $k$-vertex tree is at most $\frac {n(k-2)}{2}$. Despite significant interest, the conjecture remains unsolved. Recently, Caro, Patkós, and Tuza considered this problem for host graphs that are connected. Settling a problem posed by them, for a $k$-vertex tree $T$, we construct $n$-vertex connected graphs that are $T$-free with at least $(1/4-o_k(1))nk$ edges, showing that the additional connectivity condition can reduce the maximum size by at most a factor of 2. Furthermore, we show that this is optimal: there is a family of $k$-vertex brooms $T$ such that the maximum size of an $n$-vertex connected $T$-free graph is at most $(1/4+o_k(1))nk$.


Tuesday, May 30, 2023
4:30 PM - 5:30 PM KST
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Room B332
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IBS 이산수학그룹 Discrete Mathematics Group
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