Operating System Concepts says
when we add links, the tree structure is destroyed, resulting in a simple graph structure (Figure 11.13).
Could you create the cycle book->avi->book using symbolic links?
/avi/mail also appear under
/avi/book/count also appear under
/avi/? If both answers are no, can you make them happen?
If you have some problem understanding the figure just like I do, here is my guess: The root of the tree is a directory named "root" which contains three directory entries for subdirectory "avi", regular file "tc" and subdirectory "jim" respectively. Similar explanation for other parts.