Uses of self referencing lists

Question

Hello,

I know it is possible to create a self referencing list in languages like Python:

>>> my_list = [1,2]
>>> my_list.append(my_list)
>>> print my_list
[1,2,[...]]
>>> print my_list[0]
1
>>> print my_list[2]
[1,2,[...]]

What algorithms benefit from self referencing lists? I cannot think of one.

Thanks.

Answer 1

Most recursive problem definition uses some kind of self refrential objects or a data with self-referential definition.

I would add the wikipedia link as it provides a good readup:

• http://en.wikipedia.org/wiki/Recursion_(computer_science)

Others on SO

• http://stackoverflow.com/questions/3021/what-is-recursion-and-when-should-i-use-it
• http://stackoverflow.com/questions/1853409/recursive-sets-vs-recursive-functions
• http://stackoverflow.com/questions/717725/understanding-recursion
• http://stackoverflow.com/questions/2374006/recursive-splay-tree
• http://stackoverflow.com/questions/2085834/how-did-you-practically-use-recursion

Answer 2

If you are asking just about lists, then I can't think of something right now, except for maybe recursively creating/searching in a data structure modeled as list.

But one application of a self-referencing could be this http://stackoverflow.com/questions/1020279/self-referencing-class-definition-in-python

Answer 3

Self-referencing lists, and, generally speaking, circular data structures, can be caused when representing a graph using data structures.

For example, consider this naive representation of a graph: Each node is either an atomic value, or a list of nodes that it is linked to. A circle may cause a list to contain another list that contains the list. A self-circle, i.e., an edge from a node to itself, will cause a self-referencing list.