I need to thank Gord Wait for putting this idea back in my head in an actionable way. If you're a buzz user, you may feel beset by noise. You're following a lot of interesting people, but some of them post infrequently such that their posts are hard to discern in the flow.
There have been many calls for twitter-like buzz lists to solve this problem. Essentially, you would create lists of people whose updates you wanted to track, and then by clicking on the lists, you would see only the updates from those people.
Such lists have not been forthcoming from the buzz team. However, as Gord reminded me, you can simulate such a list by using the atom representation of the person's public activity stream, and then grouping all of the people you want to follow into a folder in reader.
The question is: What is the url to that atom stream representation? Well, it turns out it has a canonical form that looks like so:
For instance, if you wanted to follow me this way, the following URL with my user name would suffice:
Some people don't want to reveal their user name, so you're only able to get their numeric ID. It's the exact same format. Here's me via numeric ID:
In each of these URLs, the part in green represents the service you are calling, and it never changes. The part in red is a modifier indicating that you only want what the poster chooses to share with everybody. That also never changes (You can't track private posts in Google Reader because it does not support the authentication required).
This is how I'll track the 70 students I'll have using buzz in two weeks.
So, why is this called Laporte's lemma?
The title is meant as a humorous take on Leo Laporte's abandonment of buzz this past weekend because he felt people didn't notice his stuff anyhow and Louis Gray's response that that might be because he, Louis, had so much other stuff in his stream. As a result, Leo's absence went unnoticed by Louis.
In the world of mathematics, a lemma is a little side proof one does in getting to the main event or it is an easy to derive consequence of a proof that has practical import. It's in this latter sense that I meant the word in the title.