1. Three pebble games on graphs are considered: the well-known computational pebble game, the “progressive” (i.e., no recomputation allowed) version of the computational pebble game, both of which are played on directed acyclic graphs, and the quite different “breadth-first” pebble game, that is played on undirected graphs.

Es werden drei Pebble Games auf Graphen betrachtet: das wohlbekannte „computational” Pebble Game, die „progressive” (d. h. keine Wiederberechnung erlaubt) Version des computational Pebble Game, von denen beide auf directed acyclic Graphen gespielt werden, und das ziemlich verschiedene „breadth-first” Pebble Game, das auf undirected Graphen gespielt wird.