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Interviews: Bram Cohen

Author:China Magic Cube Time:2010/11/15

Bram Cohen is not only the creator of BitTorrent, the protocol responsible for between 25% and 55% of all internet traffic, but also the creator and co-creator of a number of great puzzles that he sells on his Shapeways Shop. Intrigued by yet another Shapeways Community Member with their own wikipedia article (5 and counting) and the obvious dichotomy between someone that has done more than almost anyone else to make Intellectual Property immediately and widely available for free while whilst now selling his own IP online, I decided to interview Bram.
You can find out more about Bram by checking out his Livejournal(yes, replete with Evony ad), his website or by following him on Twitter(insightful and fun).

Bram is above with two of the puzzles he has created. The white one is called Looseness Burr and can be found on his Shapeways Shop.
Joris: Bit Torrent makes it possible for anyone to download content from the web. People critical of it say that it is a tool for infringing Intellectual Property. At the same time you have a Shapeways Shop where you basically sell models based on your own intellectual property? Do you see the duality?
Continued below.

Bram: I have a lot less interesting in the subject of intellectual property than most people seem to expect. I have an interest in networking protocols, and also one in puzzles, both of which happen to bring up intellectual property issues, but I deal with such issues of necessity, not because I particularly care about them. There is the interesting question of how to get puzzles produced, and also how to try to make money off of their production, which ideally I'd like to do, but that's a secondary issue, since obviously it's impossible to make money off a puzzle which people aren't very interested in even if it's free.
I know you're not really interested in the intellectual property issue but...How would you feel if there was a "The Shapeways Bay" that offered your designs as a free download?

In some sense that already exists and I post my own stuff to it - the 'Puzzle will be played' burr site has a huge collection of burr puzzles, and most of my experience with burr puzzles comes from rebuilding most of the puzzles from that site in Burrtools. Only a tiny fraction of all puzzles have any commercial value whatsoever, so piracy isn't really an issue for them. Among the puzzles with a little bit of commercial value, the few people and companies who make them are generally quite strict about only producing things with permission, because the community is small enough that there's little gain and a lot of potential ostracism from doing otherwise. For the rare puzzle which has so much commercial potential that it might attract real knockoffs, the two approaches are to either make a brand-based premium version, as the Rubik's Cube does these days, or to ramp up supply ahead of the knockoffs while the fad moves along, as the Rubik's Cube completely failed to do when it was first introduced. Patents don't in practice help all that much. All of that is in the 'good problem to have' category though - most mechanical puzzles simply fail commercially, and it's unusual for one to succeed enough for knockoffs to be a concern.
So how did you come to make a tool that is responsible for 35% of all the internet traffic in the world?
BitTorrent is a tool for file distribution which I wrote. It's allows people who are downloading something to automatically upload it at the same time, so a very large piece of content can be delivered to a lot of people without costing a huge amount of money to whoever made it available initially. It works very well, so it's wound up using a lot of bandwidth.
How did you get people to use it in the beginning?

I made a useful tool and gave it away for free. It was handy enough to become popular.

Make any money off of it?

The company raised some investment money, and I'm currently employed working there.

How long have you been interested in puzzles?

I got obsessed with the Rubik's Cube when I was in high school, and figured out a solution to it on my own back then. It wasn't a good solution, and it took me several months of constant playing with it to find, but for a pre-teen to find a solution without any help is pretty good.

For the Rubik's cube aficionado's out there how does your solution work?

I solve the bottom edges, then three of the bottom corners, then use the missing bottom corner to quickly solve three of the middle layer pieces, then do the last bottom corner, then use F-U2FU2RUR- to finish the middle layer. Then I orient the top edges using FURU-R-F-, then orient the top corners using RUR-URUUR-, then position the top edges using R2B-RL-U2R-LF2BR2 and finally position the top corners by keyholing using F-BF and its inverse. (When I teach people I show them using FB2F, because there's no inverse and alternating to learn with that one).

How fast can you solve a Rubik's cube?

A bit less than a minute and a half. I'm not particularly fast - I'm very bad at spotting the positions of pieces.

Was it your fascination with mathematics that brought you to puzzles?

Not really, I'd say the same thing which makes me interested in math makes me interested in puzzles, although they aren't directly related. My familiarity with computational complexity gives some important insights into the fundamental nature of certain kinds of puzzles though, particularly burrs.

What kind of puzzles do you make?

My main interest started out being twisty puzzles, loosely defined as 'puzzles like the Rubik's Cube'. It generally includes puzzles in which there are a bunch of identical pieces and several operations which permute those pieces, and you scramble it and the puzzle is to unscramble it. Puzzles of this form have a number of nice properties: They're always physically one piece so parts don't get lost, they're much easier to unsolve than to solve, and it's possible to invent one without knowing how to solve it.

I've more recently gotten interested in burrs, since I learned how to use Burrtools. I'm too lazy to work on burrs unaided. I generally try to make my burrs be all identical pieces, for aesthetic reasons, and because it's a criterion which forces me to actually do some work on the puzzle myself instead of blindly giving Burrtools a set of constraints and using whatever result it spits out.

My other strange puzzle interest is puzzle rings. Almost all puzzle rings made for the last several hundred years have been the exact same design, which is a very good design but there are lots of other possibilities to explore. Puzzle rings turn out to be a very distinctive genre of puzzle, which most closely resemble packing puzzles in that they come apart easily and are hard to put back together again, but they don't come apart completely and have subtle aspects of how the rings interlock which are most of the interest of the puzzle and which there really isn't an analogue to in any other type of puzzle.

Occasionally I'll do a puzzle which is in a genre other than one of those, but my general approach is to take an interest in something and go very deep in studying that one thing.

Most of my twisty puzzle inventions wind up being collaborations with Oskar van Deventer, and he's done a bunch of work on instantiating my puzzle ring designs as well, which is why so many of my designs are on Oskar's shapeways shop. Burrtools is able to export directly to stl, which is where all the files in my shop came from.


When designing a puzzle do you start at the end? or at the beginning? Do you start with the solution or the problem?
Your question presupposes a process where the puzzle inventor comes up with a secret which is then hidden from the solver. Most of my designs are so simple that it would be impossible to follow such a process - the design constraints imposed by how it works make it challenging to come up with a puzzle at all, much less one which follows very preconceived notions of how it should work. It's an extreme version of form following function.

Explain the "form following function" issues behind puzzle design for us..

A lot of my interest in puzzles is in trying to explain to people that even very simple motions in 3-space are much more mathematically obscure than people think they are. Even Cartesian coordinates are a hack which happen to provide a simple construction of 3-space, but wind up making most of 3-space's fundamental properties appear to be spooky coincidences rather than being at the center of how it works. When I say this usually people have no idea what I'm talking about, but when people play with my puzzles the intuition gets across. Most of my puzzle ideas are based on some notion of movement, and that function almost entirely dictates the form of the puzzles, because 3d movement has very strong mathematical underpinning which it's impossible to make small stylistic variants of.
What software do you use to make your puzzles?
I generally use Burrtools for my burr puzzles. For our collaborations Oskar uses Solidworks, Rhino, and miscellaneous utilities. For specifying puzzle rings, I generally use ascii art 

 

Above is an image of the Ascii art, because our CMS is not equipped to handle it.
Could you recommend any of the tools you use?

Burrtools is an excellent tool for making burr puzzles, but it's extremely special purpose. Solidworks has a great history function, which allows you to parametrize your model so that individual dimensions can be altered and everything they interact with can be automatically adjusted to go along with it, which can make some changes be done in literally seconds which would otherwise require redoing the whole thing from scratch. Rhino is good for some transforms done on finished meshes which Solidworks is incapable of, like bending a helix. Ascii art I can't recommend in general

What brought you to Shapeways?

I think I first saw it when Oskar started posting things on it.

Why are you interested in 3D fabrication?

Many of my designs are so convoluted that it would be prohibitively difficult to make them with any process other than 3d printing, and even for ones which can be made in other ways, the amount of work necessary to do multiple revisions or even sometimes to make a single prototype is much less when done via 3d printing, and sometimes even cost competitive if the pieces are made small.

Do you think that 3D printing will become mainstream or be for a niche?

3D printing as already fairly mainstream, in that it's a common practice to 3d print a master which is then cast afterwards for commercial parts. If prices get down to somewhere around a fifth to a tenth where they are now you'll start seeing 3d printed parts as a normal process for making consumer items, particularly if the Z axis resolution is improved a lot.
The improvement of Z axis resolution(in layer resolution) is a good point. Do you see 3D printing moving forward with everyone having their own printer? Or would limitations such as this hold back such a development?
3d printers are expensive enough that it doesn't make sense for people to own them individually, since they mostly sit around unused and the amortized expenses are going up in smoke in that case (this is actually true of 2d printers as well - those things are a such a ripoff). Moving towards a person or company owning a printer and taking orders from other people to do on it has been a huge improvement in how 3d printing is done, so no, I don't see anyone owning their own 3d printer any time soon. If anything we'll see an extension to the outsource model, where companies own geographically distributed printers and are able to print something physically close to you to have it ship faster.

If 3D printing does become a process to make consumer items which items do you see it being used for? Do you see it changing society, manufacturing etc. or will the impact be more limited?
I think 3d printing is likely to result in a wider variety of products, made in shorter runs than they have been to date. There might also start being customization of shapes as well as colors like we have today, and possibly a lot of shapes in products which cause serious difficulties for traditional manufacturing processes, although the technical limitations of traditional methods aren't all that onerous, so I expect that to be a smaller phenomenon than one might hope.

Oskar informs me that you said the puzzle ring designs are all printable in metal, and the price of the 6-banded design is about $20, which is comparable to the cheapest puzzle rings bade with traditional techniques and simpler designs, so it appears that there is now at least one product for which 3d printing is just plain better and cheaper. Puzzle rings are a bit exceptional though, as they involve very little material, very precise workmanship, and have shapes which are uniquely challenging. Any chance that white gold and platinum will become available as printing materials? 

Gold maybe, white gold less sure, platinum not in the near term.
What do you think of Shapeways what should we change, what should stay the same?

The process for people to order a piece  if they aren't uploading anything needs to be streamlined a lot. Individual sellers need more control over how their shops look and are organised, for example right now if Oskar were to upload multiple sizes of one of the ring designs they'd all be displayed on the top level and completely clutter up his shop. There are also needs to be better SEO. For example, right now if you make an improved version of a model you have to upload it separately and take down the old version, completely breaking all hyperlinks to the old one. Finally, Shapeways is currently very unforgiving about requiring absolutely watertight models for printing, and it would be nice if it did a reasonable job of accepting things which were almost, but not quite, watertight.

We should be providing you guys with significant improvements to the organization of Shops and the multiple sizes in two weeks or so. The "versioning" issue is rather complex for us to solve but we are working on it. The watertight issue is also something we're trying to improve.


You've said that "my general approach is to take an interest in something and go very deep in studying that one thing." Do you think that this way of doing things is typical of an inventor? a coder? A puzzle person?

I think you have to do that to some extent to come up with an original invention. It's hard to come up with an original idea about something if you just give it a cursory examination while other people have thought about it deeply for a long time. The hardcore puzzle enthusiast community tends to have broader interests, but I suppose that's a bit misleading since they're vastly outnumbered by, for example, people who are only interested in crosswords. Programmers used to all be widely diversified, but that's becoming less so since we now have clear specialties in programming and languages which have meaningful differences instead of just being worse versions of C.

Why is no one implementing IPv6?

There isn't much clear benefit from it. What I'd really like to see is for wireless router manufacturers to have UPnP port forwarding turned on by default. Most of them have it built but turned off by default, for no apparent reason.

With HTML5 will it be possible to use a code snippet that you can put on any web page to turn that page into its own tracker, magnet URI, p2p client, player the whole shebang? 

Trackers need to have some persistent state, which I don't think HTML5 provides. The embedded video functionality is interesting though, I guess will soon find out if flash is more than just a video-playing gimmick.