Re: [Roll] terminology

[Philip Levis <pal at cs.stanford.edu>]

On Oct 30, 2009, at 6:18 AM, Julien Abeille (jabeille) wrote:

> Hi all,
>
> I am getting headackes with up the tree, to a lower rank, inward vs  
> down the tree, to a higher rank, outwards.
> Could the text only use up and down (direction), higher node, lower  
> node (nodes/parents),  and mention rank only when needed.

This seems like an excellent simplification to me.

The one weird thing that occurs is that people often talk about going  
"up" the tree as towards the root, which is the opposite of a real  
world tree. E.g., depth first search. So I'd suggest we say

Up: towards the root, decreasing rank
Down: towards the leaves, increasing rank
Higher node: lower rank
Lower node: higher rank

I think it's important to define higher and lower in terms of Rank  
since Rank is what's actually used. Otherwise you get into a weird  
situation comparing disjoint subtrees.

Parent -> higher node.
Child -> lower node.

Thoughts?

Phil