You might find useful the kind of integer index tree I'd mentioned in the earlier discussion: it's a vector of integers where each element is the index of the parent node but with _1 for the root's parent. I use this for modeling directory trees and it works well for that. Also, what I'm usually doing is looking up an item and locating its parent, or joining sub-trees into a larger tree: this structure is good (simple to code and fast) for these sorts of things. The process of breaking out sub-trees is more cumbersome than adding them in with this structure, so it depends on what you're mostly doing.
I've started a page on the j-wiki - http://www.jsoftware.com/jwiki/DevonMcCormick/Trees - to explain this structure - it's still in a preliminary state. On Fri, Nov 16, 2012 at 1:01 PM, Alexander Mikhailov <[email protected]>wrote: > > Note that Context Free Grammars tend to be ambiguous, in traditional > > programming environments we typically want a Parsing Expression > > Grammar. And we probably need "cloud sized resources" to adequately > > tackle natural language parsing. > > I have only little familiarity with PEGs; I'm not sure what is the set > of recognizable languages for PEG, comparing to LL/LR/generalized LR. > Can you recommend good resources on that? > > > These are related issues -- we could imagine a transforming operation > > in J (analogous to f.) which lifts unnecessary conditionals out of > > loops, to make serial processing more efficient. [And we could also > > imagine a transforming operation for the purpose of deploying > > something written in J into a GPU, or whatever.] We do not currently > > have that, but it's doable -- the trick to getting started would be to > > start small. > > That would be very interesting - such a transforming operation... > > > There are also many different kinds of trees. > > I need only very basics - a tree is many elements, each having exactly > one parent, with singular exception of the root. > > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > -- Devon McCormick, CFA ^me^ at acm. org is my preferred e-mail ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
