Optimal Data Reduction for Graph Coloring Using Low-Degree Polynomials
The theory of kernelization can be used to rigorously analyze data reduction for graph coloring problems. Here, the aim is to reduce a q - Coloring input to an equivalent but smaller input whose size is provably bounded in terms of structural properties, such as the size of a minimum vertex cover. I...
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| Vydané v: | Algorithmica Ročník 81; číslo 10; s. 3865 - 3889 |
|---|---|
| Hlavní autori: | , |
| Médium: | Journal Article |
| Jazyk: | English |
| Vydavateľské údaje: |
New York
Springer US
01.10.2019
Springer Nature B.V |
| Predmet: | |
| ISSN: | 0178-4617, 1432-0541 |
| On-line prístup: | Získať plný text |
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| Shrnutí: | The theory of kernelization can be used to rigorously analyze data reduction for graph coloring problems. Here, the aim is to reduce a
q
-
Coloring
input to an equivalent but smaller input whose size is provably bounded in terms of structural properties, such as the size of a minimum vertex cover. In this paper we settle two open problems about data reduction for
q
-
Coloring
. First, we obtain a kernel of bitsize
O
(
k
q
-
1
log
k
)
for
q
-
Coloring parameterized by Vertex Cover
for any
q
≥
3
. This size bound is optimal up to
k
o
(
1
)
factors assuming
NP
⊈
coNP
/
poly
, and improves on the previous-best kernel of size
O
(
k
q
)
. We generalize this result for deciding
q
-colorability of a graph
G
, to deciding the existence of a homomorphism from
G
to an arbitrary fixed graph
H
. Furthermore, we can replace the parameter vertex cover by the less restrictive parameter twin-cover. We prove that
H
-
Coloring parameterized by Twin-Cover
has a kernel of size
O
(
k
Δ
(
H
)
log
k
)
. Our second result shows that 3-
Coloring
does not admit non-trivial sparsification: assuming
NP
⊈
coNP
/
poly
, the parameterization by the number of vertices
n
admits no (generalized) kernel of size
O
(
n
2
-
ε
)
for any
ε
>
0
. Previously, such a lower bound was only known for coloring with
q
≥
4
colors. |
|---|---|
| Bibliografia: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 14 |
| ISSN: | 0178-4617 1432-0541 |
| DOI: | 10.1007/s00453-019-00578-5 |