Local Algorithms for Sparse Spanning Graphs
Constructing a spanning tree of a graph is one of the most basic tasks in graph theory. We consider a relaxed version of this problem in the setting of local algorithms. The relaxation is that the constructed subgraph is a sparse spanning subgraph containing at most ( 1 + ϵ ) n edges (where n is the...
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| Vydané v: | Algorithmica Ročník 82; číslo 4; s. 747 - 786 |
|---|---|
| Hlavní autori: | , , |
| Médium: | Journal Article |
| Jazyk: | English |
| Vydavateľské údaje: |
New York
Springer US
01.04.2020
Springer Nature B.V |
| Predmet: | |
| ISSN: | 0178-4617, 1432-0541 |
| On-line prístup: | Získať plný text |
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| Shrnutí: | Constructing a spanning tree of a graph is one of the most basic tasks in graph theory. We consider a relaxed version of this problem in the setting of local algorithms. The relaxation is that the constructed subgraph is a
sparse spanning subgraph
containing at most
(
1
+
ϵ
)
n
edges (where
n
is the number of vertices and
ϵ
is a given approximation/sparsity parameter). In the local setting, the goal is to quickly determine whether a given edge
e
belongs to such a subgraph, without constructing the whole subgraph, but rather by inspecting (querying) the local neighborhood of
e
. The challenge is to maintain consistency. That is, to provide answers concerning different edges according to the
same
spanning subgraph. We first show that for general bounded-degree graphs, the query complexity of any such algorithm must be
Ω
(
n
)
. This lower bound holds for constant-degree graphs that have high expansion. Next we design an algorithm for (bounded-degree) graphs with high expansion, obtaining a result that roughly matches the lower bound. We then turn to study graphs that exclude a fixed minor (and are hence non-expanding). We design an algorithm for such graphs, which may have an unbounded maximum degree. The query complexity of this algorithm is
poly
(
1
/
ϵ
,
h
)
(independent of
n
and the maximum degree), where
h
is the number of vertices in the excluded minor. Though our two algorithms are designed for very different types of graphs (and have very different complexities), on a high-level there are several similarities, and we highlight both the similarities and the differences. |
|---|---|
| Bibliografia: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 14 |
| ISSN: | 0178-4617 1432-0541 |
| DOI: | 10.1007/s00453-019-00612-6 |