Graph pebbling
Mathematical game played on a graph / From Wikipedia, the free encyclopedia
Dear Wikiwand AI, let's keep it short by simply answering these key questions:
Can you list the top facts and stats about Graph pebbling?
Summarize this article for a 10 year old
Graph pebbling is a mathematical game played on a graph with zero or more pebbles on each of its vertices. 'Game play' is composed of a series of pebbling moves. A pebbling move on a graph consists of choosing a vertex with at least two pebbles, removing two pebbles from it, and adding one to an adjacent vertex (the second removed pebble is discarded from play). π(G), the pebbling number of a graph G, is the lowest natural number n that satisfies the following condition:
Given any target or 'root' vertex in the graph and any initial configuration of n pebbles on the graph, it is possible, after a possibly-empty series of pebbling moves, to reach a new configuration in which the designated root vertex has one or more pebbles.
For example, on a graph with 2 vertices and 1 edge connecting them the pebbling number is 2. No matter how the two pebbles are placed on the vertices of the graph it is always possible to arrive at the desired result of the chosen vertex having a pebble; if the initial configuration is the configuration with one pebble per vertex, then the objective is trivially accomplished with zero pebbling moves. One of the central questions of graph pebbling is the value of π(G) for a given graph G.
Other topics in pebbling include cover pebbling, optimal pebbling, domination cover pebbling, bounds, and thresholds for pebbling numbers, as well as deep graphs.
One application of pebbling games is in the security analysis of memory-hard functions in cryptography.[1]