PG: What's your current take on reddit's comment system?

Y'know how in a typical CS datastructures course you'll have to build a heap, and then reimplement with an array? A heap is conceptually a balanced binary tree where every leaf is filled, while there's nothing tree-like about an array. However, your CS profs were trying to get across that any binary tree can be stored as an array, with the root in position 0, its leaves in positions 1 and 2, their leaves in positions 3, 4, 5, 6, etc. If a node doesn't have a leaf, that position in the array is empty.

Normally this is very inefficient - a totally-unbalanced (linked list) binary tree of length 20 would require a 1MB array to hold it. However, heaps are always perfectly balanced, so an array really is the most efficient implementation for them.

By restricting users to a certain number of replies to each comment (65,536), I'm effectively constraining an arbitrary tree structure to a 65,536-ary tree. Which can then be represented by an array. If held in memory, it'd be a very sparse and inefficient array.

But databases are excellent at storing sparse arrays. If I don't store a potential key, it doesn't take up any space in the DB. And with a good indexing system, I can reference any element in constant time (well, O(logN), but the log base for B-trees is so huge that it might as well be constants).

So, I'm really just applying some of the meta-principles of CS coursework to basic data structures. (Actually, I got the idea off a Slashdot posting and had to figure very little of this out on my own, but it's still really cool.)

Incidentally, there's apparently a deep connection between number systems and tree structures. You can read more about it in Chris Okasaki's Purely Functional Data Structures. Apparently, every number system corresponds to a data structure. For example, Peano arithmetic = linked lists, binary numbers = binary trees, fibonacci numbers = binomial heaps, etc. There's a short presentation on it here: http://www.informatik.uni-bonn.de/~ralf/talks/BCTCS.pdf, and I'd strongly recommend the book.

http://www.shirky.com/writings/group_enemy.html http://shirky.com/writings/broadcast_and_community.html

I agree with most of his points. Better technology can not substitute for better people, although I observe a strong correlation between mental acuity and humility and, hence, 133t hacker skills.

One of the unfortunate things about communities (reddit included) is that they tend to gravitate towards a certain conformity of opinion which then rewards people who parrot the standard opinions and stifles innovation.

I was reading a blog post recently on how someone creeped to the top of Y-Combinator karma by observing karma-award patterns and posting articles which he thought people would award karma for.

This, obviously, is an effective way of winning prestige, but prestige has rarely been a very good correlate for anything. In fact, as Pg stated in his talk at Rails Conf, even at the individual level an increase in prestige frequently has a negative impact on innovation.

Redditors have been observing the same pattern in their own community. As more people have become aware of the community (the prestige has increased), the quality of the postings and karma system has declined to the point where inane 'Bush resembles Chimpanzee'-type postings dominate the main page.

There is ultimately only one solution to this problem - the creation of walls. The last online community I participated in went through a similar phase of evolution. The content was progressively diluted until a number of core members went and created their own community. This new forum/community now has a application for membership which requires applicants demonstrate writing proficiency prior to entry.

Tie-ins to current political machinations could be articulated, but seem unnecessary at time.now

1) Small groups have higher numbers of core users

2) Private and semi-public groups have higher numbers of core users than public groups

3) People in private groups remain in the core for longer

4) A user who is in the core of one group is more likely to become a member of the core when joining another group

5) New members who eventually become part of the core are more likely to receive messages from other users who have been long-time core users

6) New members who eventually become light users are more likely to receive messages from other light users, if they receive replies at all.

This suggests some strategies for building a strong group of core users to transmit social norms. For example, having an idea of who the core users are in other similar communities and making a special effort to reach out to them if they visit your site.

Unhappily I lost the original paper and all I have are my notes, so I don't know exactly how they defined the core users offhand.