Ramsey Numbers for Trees II
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...
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Veröffentlicht in: | Czechoslovak Mathematical Journal 2021-06, Vol.71 (2), p.351-372 |
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Format: | Artikel |
Sprache: | eng |
Schlagworte: | |
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Zusammenfassung: | 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. |
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ISSN: | 0011-4642 1572-9141 |
DOI: | 10.21136/CMJ.2021.0328-19 |