(data structure)

**Definition:**
A theoretical data structure for n items. It starts with a *balanced binary search tree* of about √(n) nodes. The *leaf* nodes lead to "tentacles" or *linked lists*, each of about √(n) nodes.

**Aggregate child** (... is a part of or used in me.)

*balanced binary search tree*, *linked list*.

*Note:
It is described to prove a theorem, not as a useful data structure. *

Synder says the tentacles may be ordered, unordered, or semi-ordered. For faster access to the end of the tentacle for updates, there can be links from the beginning (*head*) to the end (*tail*).

* This note gives more details to justify the counts above. The body consists of about √(n) nodes, of which about √(n)/2 would otherwise be considered leaf nodes. Since each node has two subtrees, there are about 2 × √(n)/2 = √(n) tentacles. Therefore each tentacle has about (n - √(n)) / √(n) = √(n)-1 nodes.*

Author: PEB

**Lawrence Snyder**, *On Uniquely Represented Data Structures*, Proc. 18th Annual Symposium on Foundations of Computer Science (FOCS), pp 142-146, 1977.

Go to the Dictionary of Algorithms and Data Structures home page.

If you have suggestions, corrections, or comments, please get in touch with Paul Black.

Entry modified 29 August 2014.

HTML page formatted Fri Feb 23 10:06:07 2018.

Cite this as:

Paul E. Black, "jelly-fish", in
*Dictionary of Algorithms and Data Structures* [online], Vreda Pieterse and Paul E. Black, eds. 29 August 2014. (accessed TODAY)
Available from: https://www.nist.gov/dads/HTML/jellyfish.html