منابع مشابه
Searching and Pebbling
We relate the search number of an undirected graph G with the minimum and maximum of the progressive pebble demands of the directed acyclic graphs obtained by orienting (7. Towards this end, we introduce node-searching, a slight variant of searching, in which an edge is cleared by placing searchers on both of its endpoints. We also show that the minimum number of searchers necessary to node-sea...
متن کاملThe Complexity of Pebbling and Cover Pebbling
This paper discusses the complexity of graph pebbling, dealing with both traditional pebbling and the recently introduced game of cover pebbling. Determining whether a configuration is solvable according to either the traditional definition or the cover pebbling definition is shown to be NP -complete. The problem of determining the cover pebbling number for an arbitrary demand configuration is ...
متن کاملPebbling and optimal pebbling in graphs
Given a distribution of pebbles on the vertices of a graph G, a pebbling move takes two pebbles from one vertex and puts one on a neighboring vertex. The pebbling number Π(G) is the least k such that for every distribution of k pebbles and every vertex r, a pebble can be moved to r. The optimal pebbling number ΠOPT (G) is the least k such that some distribution of k pebbles permits reaching eac...
متن کاملResolution and Pebbling Games
We define a collection of Prover-Delayer games to characterise some subsystems of propositional resolution. We give some natural criteria for the games which guarantee lower bounds on the resolution width. By an adaptation of the size-width tradeoff for resolution of [10] this result also gives lower bounds on proof size. We also use games to give upper bounds on proof size, and in particular d...
متن کاملCircuits, Pebbling and Expressibility
We give characterizations of nondeterministic complexity classes such as NP and PSPACE and the classes in the polynomial time hierarchy in the two-person pebble game model [VT89]. These characterizations motivate the definitions of these classes using firstorder sentences extending the results in [Im82]. It is shown that the role-switches resource in the pebble games closely model the levels of...
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ژورنال
عنوان ژورنال: Theoretical Computer Science
سال: 1986
ISSN: 0304-3975
DOI: 10.1016/0304-3975(86)90146-5