A Generalization of AVL Trees
A generalization of AVL trees is proposed in
which imbalances up to (triangle shape) is a small 
integer.  An experiment is performed to compare these
trees with standard AVL trees and with balanced 
trees on the basis of mean retrieval time, of amount
of restructuring expected, and on the worst case 
of retrieval time.  It is shown that, by permitting
imbalances of up to five units, the retrieval time 
is increased a small amount while the amount of restructuring
required is decreased by a factor of ten. 
 A few theoretical results are derived, including the correction
of an earlier paper, and are duly compared 
with the experimental data.  Reasonably good correspondence is found.
CACM August, 1973
Foster, C. C.
