Ad Hoc, Self-Supervising Peer-to-Peer Search Networks – nice paper on a proposed architecture for p2p networks, built on primitives which are so simple they’re obviously right. :-) Abstract:
Peer-to-peer search networks are a popular and widely deployed means of searching massively distributed digital object repositories. Unfortunately, as such networks grow, they place an increasingly overwhelming load on some or all of the participating nodes. We examine how to reduce the load on nodes by allowing them to self-organize into a relatively efficient network, and then self-tune to make the network even more efficient. Unlike previously studied architectures, our “ad hoc, self-supervising” networks avoid restrictions on who a node can connect to or what information can be exchanged. This makes the network topology quite flexible and tuneable. Our results indicate that our ad hoc networks are more efficient than popular supernode topologies for several important scenarios.
Thirty years of research on query languages can be summarized by “we have moved from SQL to XQuery.” At best, we have moved from one declarative language to a second declarative language with roughly the same level of expressiveness.
From The Lowell Database Research Self-Assessment [spotted in Communications of the ACM]
As promised, though I’m still working on the shiny LaTeX article which actually explains all this stuff…
From the README:
This is an investigative/learning exercise in transforming process algebraic expressions into labelled transition systems according to their operational semantics, using Python and Haskell.
It started out just as an exercise in operational semantics, using Python because it’s the language I get things done fastest in. That proved interesting enough that I wanted to re-do it in Haskell, which I’m learning and which arguably handles this sort of thing better.
The Python version is more advanced. It includes mu-recursion, which the Haskell doesn’t, and is quite tidy IMHO. OTOH the Haskell is less developed, and in particular the functions for actually creating the graphs could, I’m sure, be improved. Always nice to have some future work to do…
I’m publishing this in case anyone is interested in the code. In particular, it is perhaps useful as an example of:
I’m working on a paper describing the problem, the semantics, and the approaches taken in the two languages, but it’s very much an ongoing WIP and isn’t ready to publish yet.
Homepage for this work: http://www.cs.swan.ac.uk/~csandy/research/op_sem_py_hs/
I’ve got two books on the go at the moment (Potter can wait): Neal Stephenson‘s Quicksilver, and Charlie Stross‘ Accelerando. I’ve just about finished the former, and according to Plucker, I’m 46% of the way through the latter – so perhaps some of the opinions expressed below will change…
These are both science fiction works. The first is unusual for sci-fi in that it’s set (mainly) in the seventeenth century; Newton and Liebniz are key (though secondary) characters, and it seems mainly to be about religious tensions (as you’d expect from the setting), the nascent scientific movement, the nature of money and markets, and a very nascent anti-slavery movement, though I’m not sure where that’s going to go. The second is based around the futurism idea of the Singularity, a supposed point in the future where the rate of change of scientific knowledge and human ability goes nonlinear, basically.
Read the rest of this entry »
More Robot Wisdom goodies: Feynman/von Neumann US postage stamps, future windfarms (“twelve [offshore] wind farms of 100 units would meet the UK government’s 10% target for renewable sources” – so let’s build 120?), and finally short excerpts from Rwanda genocide accounts book, eg:
Saving the babies, that was not practical. They were whacked against walls and trees or they were cut right away. They were killed more quickly, because of their small size and because their suffering was of no use. The babies could not understand the why of the suffering; it was not worth lingering over them.
Chilling. We saw Hotel Rwanda last week, and I gotta say, it was one of the hardest films I’ve ever watched – up there with Threads in terms of visceral human horror, made worse by its reality. Highly recommended.
Oh my yummy yum yum yummy… [bash]
About time somebody did this. I will, of course, wait for the split/ergonomic version, if only because it confuses and annoys people who try to use my computer.
There’s a bit in Brian Eno’s A Year With Swollen Appendices where he’s in Egypt, and a boy rides past on a bike shouting “I am here! I am here!” repeatedly, and Eno dubs this “perhaps the single and central message of humanity”. I’ve always really liked that.
As I sat in the lobby of our hotel in London last week, I mused on the feeling of obscelescence and redundancy. There’s a moment in Accelerando where one of the central characters loses all the computational stuff that augments his senses and mental faculties – he’s reduced to bare meat and a comparatively sluggish consciousness. This leads him (even after he’s fully restored to bright shining augmented posthumanism) to worry a lot about how long he can remain on the bleeding edge. Now, everyone feels this at some point, I believe: the horror (or at least angst) of realising that What Once Was has passed, never to be surpassed or even attained again. The loss of the intellect, the passing of the peak, the fading of the beauty, whatever it is. The fear that all that lies ahead is swimming ever harder, if one can even manage that, only to drift inexorably downstream.
So, a fundamental question is how to deal with this? If all my best lies behind, then what of the future? Naturally, having hit my early thirties, I have somewhat irrationally started to worry at this question myself. It’s absurd I know, but there you go.
The answer, it seems, is just this: to have hope and not worry about it. Nothing more that. For one thing, your best days may actually lie ahead. However, a stronger statement is the following: now is what matters – the past is gone and cannot be changed, and the future is yet to arrive, if at all. The question is not “what have you done?” or even “what would you do?”, but simply “what are you doing?“
As such, I contend that just as “I am here” is the single and central message of humanity, so is “What are you doing?” the single and central question. (Not “where are you?”, I note.)
Of course, the real question is what do I have to do to discuss this with Brian over a glass of wine some time? ;-)
(Aside: it’s so hard to find anything specific in Eno’s book, because you just keep getting distracted – there’s an interesting idea or fact or insight on every page. Given that I’m reading Quicksilver at the mo, this one particularly caught my eye: 16 October. I also asked Anthea how many mature oaks she thought it would have taken to build a top-of-the-line ship in Nelson’s day. She guessed ten. The anstonishing answer (from Brewer’s) is about 3,500 – 900 acres of oak forest. She said, “I wonder what we’re doing now that’s as wasteful as that”. I said it’s still called Defence.)
50 Eno Moments, which I don’t have time to read right now.
I’m still here, I’ve just been too busy to blog. However, while I’m waiting for ghc-6.4 to compile (that’s my excuse anyway), I thought I’d do a quick blogdump…
I was going to write about my week in London, and a bit about what I’ve been reading lately, but I started by writing the stuff below instead, and now I think that’s enough for one post, so I’ll publish this and follow up with the rest maybe tomorrow or Sunday. (Short version: London fun except bombs, Quicksilver OK, Accelerando completely barmy but getting a bit dull at 40%). Colin, I should warn you that the rest of this post is of the kind you don’t like. The London diary thing might be better. Sorry!
Work’s been truly excellent this week. No students so no teaching, and also no admin for a while too. Some time I need to do some preparation for next year’s teaching, but for the next two months I’m mainly going to be focussing on research at last, aiming to break the back of my MPhil. I made a breakthrough on the parsing side last Sunday (or rather, I cleared up a misconception I’d been harbouring), but have spent this week on a different tack, learning about operational semantics through the magical medium of Python. Specifically, Markus gave me a toy process algebra and its semantics, and outlined the algorithm for turning expressions in the PA into their labelled transition systems, then I went away and programmed it.
It’s been excellent fun, and I got it basically done in no time at all, mainly because I chose to do it in Python. It’s quite remarkable, in fact… For months I’ve been struggling to get anywhere with my research, and it’s been very depressing and making me feel like I can’t hack this stuff. Now I realise it’s just that I’m a complete Haskell newbie. If I was doing my research in Python, I’d probably have finished by now. Alas, I have to do it in Haskell, because of the system we’re interacting with, but it’s encouraging to realise my problems relate to the language/paradigm I’m working in, not some basic failing on my part to understand what the heck I’m trying to do.
Anyway, I’m writing up an article explaining what I’ve done, and either later today or early next week I’ll publish it and my code, so anyone who reads the above and says “huh?” can take a look if they want. (JOn? You reading this? ;-))
Next week is graduation week at Swansea University and I’m acting as a marshall on Monday, which is Science day. So I get to see all this year’s third years do their stuff. With luck and effort, I should be there myself this time next year.
What else is new? I recently made the shift from ion to ion3. Ion’s been by window manager of choice for about three years now, mainly because I can’t be bothered with all that tedious point-and-click move-and-resize nonsense you have to do with windows in most WMs. TR occasionally moans at me that it’s modal but I don’t see it as a problem, it works for me and is extremely keyboard friendly and fast, so I’m happy. But I’ve been feeling behind the curve, and in particular some apps (eg the Gimp) don’t play well with the tiled model – which is why ion3 is nice because it adds optional “float workspaces” which act more like a conventional tedious point-and-click point-and-resize window manager if and when that’s what you need. Making the move was non-trivial because my config files had to be ported to Lua, but now it’s done and I’m very happy with my window manager indeed. Once again, I’d recommend looking at Ion if you’re getting dissatisfied with your Gnome/KDE experience and want to strip things down.
Finally, a couple of Python goodies via the Python-URL: try/except vs if/else in terms of speed (an oldie but a goodie, especially when advocating Python to curmudgeons), and Sparklines, which are kinda weird and kinda cool, but I’ve no idea if they’d actually be useful.
Well, Bash and I are in London for her birthday – lovely day for it.
First we heard of the explosions was at about 10:15, waiting for the lift to arrive in the hotel, when my parents rang. “Are you OK?” “Er, yeah, fine thanks. Whhhyyyyy…?”
The hotel’s on The Strand. Five minutes walk to Trafalgar Square, strangely quiet (especially after yesterdays Olympic crowds), with sirens zooming past constantly. We’re now at the Royal Society, which was our intended first stop on a day to also include St Paul’s Cathedral, the Tate Modern, Tate Britain (via the Tate-2-Tate boat), maybe a shufti at Parliament, and then birthday dinner with London friends in Earl’s Court. Needless to say, most of these plans are on hold just now. St Paul’s to Tate to Tate is all do-able on foot/boat, but to get to St Paul’s we have to get to The City, which might not be a good idea assuming these explosions have an economically motivated component.
It’s been a good week, up to now, though. The show’s going very well and everybody loves the calculator. Having now used it quite a bit, I can definitely say it’s Way Cool and very impressive.
I went to the Science Museum for a bit on Tuesday, mainly checking out the Computer Science, Maths, and Telecoms Displays. I found it very disappointing. The best part is easily the Babbage stuff – difference engines, and his brain – but the rest seemed like it hadn’t been updated for 20 years. The CS stuff was also disappointingly focussed on machinery, but there’s so much more to computing than that, and increasingly so. The computers themselves are far less interesting than what you do with them and how (IMHO) but there was almost nothing on that. There was a fifteen-foot wide display on the history of the British Punched Card Calculator industry (not even general purpose computers!), but only a small card with about fifteen lines of text for Alan Turing! A travesty! Telecoms was not much better, and didn’t seem to have changed at all since I visited it with my eldest brother Mike back when I was eleven. Actually, that’s not true, it had changed: most of it had stopped working.
The bookshop was quite good, though.
Tuesday evening I headed to Greenwich to visit Rich and Em, and meet with a couple of the old Frontier possee, viz Jon and Mark F. This took place in a superb pub in Greenwich – The Union, with a microbrewery and some excellent excellent beers. The “chocolate beer” (stout) was particularly fine.
I spent yesterday afternoon planning what to do for the next three days (now out the window, it seems), then met Bash at Paddington at 7:30, and whisked her to the National Film Theatre for Antenna – a bi-monthly showcase of music videos. Some really good stuff, in particular “Sentimental Journey” by Yuki – very thoughtful and gentle. The place was, of course, full of achingly cool people. :-)
Anyway, think we’re going to have a look round the exhibition now, and I don’t know, maybe stay here all day. Hope everyone reading this is OK and your loved ones are accounted for…