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Graphs

cdixon.org

44 pointsjmillerinc15 comments

I'm a computer scientist, and I call the (very old) study of graphs "graph theory". How is "network theory" different?

And is it just me, or is it painful to read this? It has the feel of a student taking an intro course on optimization, then exclaiming, "everything is an optimization problem!" I mean, sure, this is true, but it's tautological and feels forced to me.

And sorry, but Twitter's main innovation was discarding symmetry? People have been subscribing (an asymmetric relation) to things on the internet and otherwise for ages.

...(an asymmetric relation) to things on the internet

You mean a link? ;)

With regards to your other points, I do think the general premise of the post is correct that the pendulum is swinging back (?) towards more flexible data structures (e.g. graphs).

The writing does come across as though the author just had an epiphany ... hey... these things are all graphs...

Yeah, and so are lots of other things.

Social Graph is (or graphs in general are) the buzzword of the day, or perhaps year. It's not surprising that everything is being phrased in terms of it.

> Twitter's main innovation was discarding symmetry?

This is a common statement that benefits from explicit context: Twitter's innovation specifically was importing the "asymmetric follow" into a social network, a graph in which nodes represent individual people and in which relations are generally public.

What was the social network with public relations between people that failed because the "follow" was symmetric?

Symmetric follow doesn't have to fail for asymmetric follow to succeed. Twitter's innovation allowed them to create and serve new use-cases. That's all

I agree. It was about building the structure of a social network around the "asymmetric follow," and doing it in a way that facilitated the curated transitivity that Chris talks about.

My experience is that mathematicians and computer scientists use "graph," and engineers use "network." I specifically took a course in an engineering faculty called "network theory."

'Graph' is the next hottest buzzword on the internet, thanks to Facebook.

I down voted you by accident! My bad.

Yes, it was painful to read and I missed the whole point of the post unless it is just listing of where we find and use "graphs." I think this is a post out of his comfirt zone; I like his VC and startup posts better.

>"One of Twitter’s central innovations was to discard symmetry: you can follow someone without them following you."

Apparently Twitter rebranded the concept of a hyperlink.

>"I expect we’ll look back on the next few years as the golden age of graph innovation."

I would say that the 'golden age of graph innovation' began much before this. Which is why in Computer Science, as he describes, we have a special edition of graph theory named 'network theory'. I wonder what that's for!

I've definitely noticed a trend towards graph based thinking in recent computer science publications. My half baked theory on this is as follows:

Graph based thinking is a result of the rise of social networking. The term "social network" wasn't common until I was a senior in college. Back then most computer scientists thought of things in terms of matrices - rows and columns. After 2004 when facebook became the most popular software in the college universe, people became much more interested in graphs (social and otherwise). I believe this lead many young computer scientists to start thinking in terms of graphs - vertices and edges. If you read comp sci papers written by people over the age of 30, many of them still express things in terms of matrices.

In my understanding, graphs can be faster to process and in many cases easier to traverse. But I believe that the shift in thinking has more to do with popular trends in software than it does any technical advantage of graphs over other ways of thinking.

No, your premise is wrong. Graphs are ancient within CS.

Linear algebra and graph theory do have some deep connections though.

Perhaps people stopped talking about matrices because social graphs are sparse. Also, most of the time papers (esp. system papers) are written to solve a problem and if the paper proposes a solution to solving a social graph related problem then that's what the author will use because it's easier for readers to relate.

The idea of graphs is a very old and very interesting topic for mathematicians too. See http://en.wikipedia.org/wiki/Seven_Bridges_of_K%C3%B6nigsber...

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