Title
Search for the end of a path in the d-dimensional grid and in other graphs
Abstract
We consider the worst-case query complexity of some variants of certain P P A D complete search problems. Suppose we are given a graph G and a vertex s is an element of V (G). We denote the directed graph obtained from G by directing all edges in both directions by G'. D is a directed subgraph of G' which is unknown to us, except that it consists of vertex-disjoint directed paths and cycles and one of the paths originates in s. Our goal is to find an endvertex of a path by using as few queries as possible. A query specifies a vertex v is an element of V (G), and the answer is the set of the edges of D incident to v, together with their directions. We also show lower bounds for the special case when D consists of a single path. Our proofs use the theory of graph separators. Finally, we consider the case when the graph G is a grid graph. In this case, using the connection with separators, we give asymptotically tight bounds as a function of the size of the grid, if the dimension of the grid is considered as fixed. In order to do this, we prove a separator theorem about grid graphs, which is interesting on its own right.
Year
DOI
Venue
2012
10.26493/1855-3974.788.89a
ARS MATHEMATICA CONTEMPORANEA
Keywords
Field
DocType
Separator,graph,search,grid
Graph,Combinatorics,Vertex (geometry),Directed graph,Mathematical proof,Lattice graph,Grid,Mathematics,PPAD,Special case
Journal
Volume
Issue
ISSN
12
2
1855-3966
Citations 
PageRank 
References 
0
0.34
3
Authors
5
Name
Order
Citations
PageRank
Dániel Gerbner14621.61
Balázs Keszegh215624.36
Dömötör Pálvölgyi320229.14
Günter Rote41181129.29
Gábor Wiener56410.65