Ramsey numbers for trees II

Zhi-Hong Sun

Czechoslovak Mathematical Journal (2021)

  • Volume: 71, Issue: 2, page 351-372
  • ISSN: 0011-4642

Abstract

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Let r ( G 1 , G 2 ) be the Ramsey number of the two graphs G 1 and G 2 . For n 1 n 2 1 let S ( n 1 , n 2 ) be the double star given by V ( S ( n 1 , n 2 ) ) = { v 0 , v 1 , ... , v n 1 , w 0 , w 1 , ... , w n 2 } and E ( S ( n 1 , n 2 ) ) = { v 0 v 1 , ... , v 0 v n 1 , v 0 w 0 , w 0 w 1 , ... , w 0 w n 2 } . We determine r ( K 1 , m - 1 , S ( n 1 , n 2 ) ) under certain conditions. For n 6 let T n 3 = S ( n - 5 , 3 ) , T n ' ' = ( V , E 2 ) and T n ' ' ' = ( V , E 3 ) , where V = { v 0 , v 1 , ... , v n - 1 } , E 2 = { v 0 v 1 , ... , v 0 v n - 4 , v 1 v n - 3 , v 1 v n - 2 , v 2 v n - 1 } and E 3 = { v 0 v 1 , ... , v 0 v n - 4 , v 1 v n - 3 , v 2 v n - 2 , v 3 v n - 1 } . We also obtain explicit formulas for r ( K 1 , m - 1 , T n ) , r ( T m ' , T n ) ( n m + 3 ) , r ( T n , T n ) , r ( T n ' , T n ) and r ( P n , T n ) , where T n { T n ' ' , T n ' ' ' , T n 3 } , P n is the path on n vertices and T n ' is the unique tree with n vertices and maximal degree n - 2 .

How to cite

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Sun, Zhi-Hong. "Ramsey numbers for trees II." Czechoslovak Mathematical Journal 71.2 (2021): 351-372. <http://eudml.org/doc/297748>.

@article{Sun2021,
abstract = {Let $r(G_1, G_2)$ be the Ramsey number of the two graphs $G_1$ and $G_2$. For $n_1\ge n_2\ge 1$ let $S(n_1,n_2)$ be the double star given by $V(S(n_1,n_2))=\lbrace v_0,v_1,\ldots ,v_\{n_1\},w_0$, $w_1,\ldots ,w_\{n_2\}\rbrace $ and $E(S(n_1,n_2))=\lbrace v_0v_1,\ldots ,v_0v_\{n_1\},v_0w_0, w_0w_1,\ldots ,w_0w_\{n_2\}\rbrace $. We determine $r(K_\{1,m-1\},$$S(n_1,n_2))$ under certain conditions. For $n\ge 6$ let $T_n^3=S(n-5,3)$, $T_n^\{\prime \prime \}=(V,E_2)$ and $T_n^\{\prime \prime \prime \} =(V,E_3)$, where $V=\lbrace v_0,v_1,\ldots ,v_\{n-1\}\rbrace $, $E_2=\lbrace v_0v_1,\ldots ,v_0v_\{n-4\},v_1v_\{n-3\}$, $v_1v_\{n-2\}, v_2v_\{n-1\}\rbrace $ and $E_3=\lbrace v_0v_1,\ldots , v_0v_\{n-4\},v_1v_\{n-3\},$$v_2v_\{n-2\},v_3v_\{n-1\}\rbrace $. We also obtain explicit formulas for $r(K_\{1,m-1\},T_n)$, $r(T_m^\{\prime \},T_n)$$(n\ge m+3)$, $r(T_n,T_n)$, $r(T_n^\{\prime \},T_n)$ and $r(P_n,T_n)$, where $T_n\in \lbrace T_n^\{\prime \prime \},T_n^\{\prime \prime \prime \},T_n^3\rbrace $, $P_n$ is the path on $n$ vertices and $T_n^\{\prime \}$ is the unique tree with $n$ vertices and maximal degree $n-2$.},
author = {Sun, Zhi-Hong},
journal = {Czechoslovak Mathematical Journal},
keywords = {Ramsey number; tree; Turán's problem},
language = {eng},
number = {2},
pages = {351-372},
publisher = {Institute of Mathematics, Academy of Sciences of the Czech Republic},
title = {Ramsey numbers for trees II},
url = {http://eudml.org/doc/297748},
volume = {71},
year = {2021},
}

TY - JOUR
AU - Sun, Zhi-Hong
TI - Ramsey numbers for trees II
JO - Czechoslovak Mathematical Journal
PY - 2021
PB - Institute of Mathematics, Academy of Sciences of the Czech Republic
VL - 71
IS - 2
SP - 351
EP - 372
AB - Let $r(G_1, G_2)$ be the Ramsey number of the two graphs $G_1$ and $G_2$. For $n_1\ge n_2\ge 1$ let $S(n_1,n_2)$ be the double star given by $V(S(n_1,n_2))=\lbrace v_0,v_1,\ldots ,v_{n_1},w_0$, $w_1,\ldots ,w_{n_2}\rbrace $ and $E(S(n_1,n_2))=\lbrace v_0v_1,\ldots ,v_0v_{n_1},v_0w_0, w_0w_1,\ldots ,w_0w_{n_2}\rbrace $. We determine $r(K_{1,m-1},$$S(n_1,n_2))$ under certain conditions. For $n\ge 6$ let $T_n^3=S(n-5,3)$, $T_n^{\prime \prime }=(V,E_2)$ and $T_n^{\prime \prime \prime } =(V,E_3)$, where $V=\lbrace v_0,v_1,\ldots ,v_{n-1}\rbrace $, $E_2=\lbrace v_0v_1,\ldots ,v_0v_{n-4},v_1v_{n-3}$, $v_1v_{n-2}, v_2v_{n-1}\rbrace $ and $E_3=\lbrace v_0v_1,\ldots , v_0v_{n-4},v_1v_{n-3},$$v_2v_{n-2},v_3v_{n-1}\rbrace $. We also obtain explicit formulas for $r(K_{1,m-1},T_n)$, $r(T_m^{\prime },T_n)$$(n\ge m+3)$, $r(T_n,T_n)$, $r(T_n^{\prime },T_n)$ and $r(P_n,T_n)$, where $T_n\in \lbrace T_n^{\prime \prime },T_n^{\prime \prime \prime },T_n^3\rbrace $, $P_n$ is the path on $n$ vertices and $T_n^{\prime }$ is the unique tree with $n$ vertices and maximal degree $n-2$.
LA - eng
KW - Ramsey number; tree; Turán's problem
UR - http://eudml.org/doc/297748
ER -

References

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