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On the size Ramsey number of all cycles versus a path. (English) Zbl 1460.05123

Summary: We say \(G \to ( \mathcal{C} , P_n )\) if \(G - E ( F )\) contains an \(n\)-vertex path \(P_n\) for any spanning forest \(F \subset G\). The size Ramsey number \(\hat{R} ( \mathcal{C} , P_n )\) is the smallest integer \(m\) such that there exists a graph \(G\) with \(m\) edges for which \(G \to ( \mathcal{C} , P_n )\). A. Dudek et al. [ibid. 341, No. 7, 2095–2103 (2018; Zbl 1387.05163)] proved that for sufficiently large \(n\), \(2 . 0036 n \leq \hat{R} ( \mathcal{C} , P_n ) \leq 31 n\). In this note, we improve both the lower and upper bounds to \(2 . 066 n \leq \hat{R} ( \mathcal{C} , P_n ) \leq 5 . 25 n + O ( 1 )\). Our construction for the upper bound is completely different than the one considered by Dudek et al. [loc. cit.]. We also have a computer assisted proof of the upper bound \(\hat{R} ( \mathcal{C} , P_n ) \leq \frac{ 75}{ 19} n + O ( 1 ) < 3 . 947 n\).

MSC:

05C55 Generalized Ramsey theory
05D10 Ramsey theory
05C42 Density (toughness, etc.)

Citations:

Zbl 1387.05163

References:

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