Memoirs of the American Mathematical Society 2001; 127 pp; softcover Volume: 152 ISBN10: 0821827219 ISBN13: 9780821827215 List Price: US$54 Individual Members: US$32.40 Institutional Members: US$43.20 Order Code: MEMO/152/724
 Readership Graduate students and research mathematicians interested in group theory and generalizations. Table of Contents  Introduction
 Graphs of groups, tree actions and edgeindexed graphs
 \(Aut(X)\) and its discrete subgroups
 Existence of tree lattices
 Nonuniform coverings of indexed graphs with an arithmetic bridge
 Nonuniform coverings of indexed graphs with a separating edge
 Nonuniform coverings of indexed graphs with a ramified loop
 Eliminating multiple edges
 Existence of arithmetic bridges
 Bibliography
