the old and the new

I’m just back from a 2 day residential Theo Murphy scientific workshop held in the Royal Society’s Kavli Centre at Chicheley Hall.  It’s my first visit there, and I can certainly recommend it as a marvellous venue for a workshop: great facilities, marvelous food, and friendly, efficient staff.  The science was great fun: I learned lots of new things, discovered links between seemingly diverse areas, and had interesting discussions over food and coffee.  I’m buzzing with ideas, which is the whole point!

I did the usual “photograph from my bedroom window” thing, which had a somewhat different from usual view:

first day of the workshop, view due east, into the rising sun

Oh, and then I took a photo from the other window in my bedroom:

first day of the workshop, view due south

Blissful.  I found an amusing view from the window half way down the main stairs:

A lovely formal garden, with lawns, paths, clipped bushes and trees, and, just visible at the vanishing point of the path … a wind farm!  The old and the new collide.

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the power of abstraction

Prof Karen Spärk Jones

Prof Barbara Liskov

Last week I popped down to London to attend this year's annual Karen Spärk Jones lecture, sponsored by the BCS and IBM.  This year's speaker was Professor Barbara Liskov, from MIT, winner of the 2008 ACM A.M. Turing award.  Her talk was titled "The power of abstraction", and she gave us an historical overview of her work.

The excellent talk was videoed, and should be online at some point.  Here I just want to pick up on the points that particularly resonated for me.

She started off talking about the software crisis of the early 1970s.  There have been several software crises: this was probably the first named one.  People didn't know how to write large pieces of software, there was no methodology, and the programming languages of the day didn't help.  Dijkstra had published his classic paper, Go To Statement Considered Harmful, in Comms ACM in 1968, calling attention to one aspect of the problem.  Nowadays everyone has heard of this paper;  "considered harmful" in a title has become a CS trope.

What I didn't realise about his paper, however, was the reaction to it.  Liskov explained that many programmers were insulted: of course they could write understandable programs with gotos.  But more interestingly, there was a doubt about whether it was even possible to write all programs without gotos.  Today, of course, this problem is solved; we deride "spaghetti programming", and instead use languages that incorporate structured gotos encapsulated in commands such as if, for, while, break, continue, and try. (Although OO allows the possibility of spaghetti messaging.)

Liskov went on to talk about her own contributions to teasing out what was needed to structure code: the abstract data type.  She and her team designed and implemented the influential language CLU (short for "cluster", the name of its abstraction mechanism), which included ADTs, static type checking, separate compilation, polymorphism, iterators, and exception handling --- but no goto statement.

For this and subsequent work, Liskov won the prestigious Turing Award in 2008.  She said that when the award was announced, some student commented: "What did she get this award for? Everyone knows this, anyway!"  Precisely: everyone does, now.

Liskov finished off by talking about the present. We have seen Moore's Law take a right-angled turn recently: instead of chips getting small and faster, they have gone multi-core.  In the past, we have not had to worry too much about parallel processing, except in certain specialised domains, because Moore's Law would provide a single processor with the required power in a few years.  Now, for the first time, we have to bite the bullet of parallelism in everyday computing.  Liskov is now working on methodologies and language support for parallel computing, not for systems with just 4 or 8 cores, but with hundreds or thousands of cores.

In my mind, this folded neatly back to the beginning of her talk, and a relevant quote from Dijkstra's paper:

Our powers to visualize processes evolving in time are relatively poorly developed.  For this reason we should do ... our utmost to shorten the conceptual gap between the static program and the dynamic process, to make the correspondence between the program (spread out in text space) and the process (spread out in time) as trivial as possible. ...
    The unbridled use of the go to statement has an immediate consequence that it becomes terribly hard to find a meaningful set of coordinated in which to describe the process progress.

Back in the 1980s I was using occam, a parallel programming language.  One thing that struck me forcibly at the time was that the traditional linear textual form of occam code was completely divorced from the underlying static parallel structure (let alone the parallel temporal execution structure).  It was very easy to get lost in a spaghetti of communication channels.  I was so irritated, I even developed a 2D visualisation of the program structure.

So, what are the right static structures and abstraction principles to help us build dynamic parallel programs?  There are already many languages with parallelism, but I suspect that in 40 years time we will look back on them with the same pity we today reserve for the humble go to.  Let's hope Liskov and her successors can find the answer.

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the rise and fall of Ctrl-S

I first used a computer back in the late 1970s, when I was an undergraduate physics student. In those days, we wrote programs on punched cards. To lose your program, you had to lose the cards (or, actually, just shuffle them).  To prove we never throw anything away, here is a program from the 1970s:

a program statement from yesteryear: 12  MAG(J,K) = 0

a whole program; no idea what it does

By the time I was a research student, punched cards had given way to text editors through VT100 terminal sessions.  I wrote my thesis in troff (one of my fellow students was writing his in this new-fangled thing called TeX), using the ZED line editor.  In order to save your changes, you had to exit the editor, save, and restart the editor, a non-trivial sequence of operations that interrupted the writing flow.  However, by the time I was writing up, the IBM 370 mainframe was on its last legs, about to be replaced by a new IBM 3081, and crashing frequently.  So I got in the habit of exiting the editor every 5-10 minutes, saving, and re-entering.

Frequent saving was ingrained in my workflow by the time applications came uniformly equipped with Ctrl-S.  (Saving without exiting.  Luxury!)  Every time I would pause to think what to write next, in word processor, spreadsheet, or text editor, I would automatically hit Ctrl-S.  It's now an automatic behaviour.

But modern applications no longer use Ctrl-S.  They just continually save, automatically. There's no need to keep saving explicitly.  Most applications that have an auto-save feature also let you do your own saves in between.  But some applications no longer have a user save command at all.  I noticed this first with Evernote, and then with Google Docs.

Fortunately, these applications haven't mapped Ctrl-S to any other function (mail programs where Ctrl-S means "send" are a real nightmare), so nothing bad happens if I do reflexively hit Ctrl-S.  Which I do sometimes, because it feels really weird not to keep saving after all these years.

Three generations of saving technology: manual-slow-and-clunky, manual-easy, automatic. That's probably progress.

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interesting use of the present tense

I was surfing an on-line TV channel guide, to find when a particular episode of Wizards v Aliens  that we had missed was being repeated.  I came across:

TV channel guide. See what you can watch today, yesterday and tomorrow.

"See what you can watch yesterday".  This really is living in the future (but watching the present)!

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still here

Guardian item on Mayan apocalypse

I see the world didn't end after all, only the Mayan calendar did.

I suppose that means I still have to do my Christmas shopping, and mark all those exam scripts....

Ah, well.

So, of course, the next end of the world is Monday 31 December 2012, when the Western calendar ends.

What do you mean, that calendar starts again on Tuesday 1 January 2013?

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oh, I do so hope not

40 years ago today, 14 December 1972, Eugene Cernan was the last man to walk on the Moon.

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retrospective holiday diary day 4: archaeology

Sunday 23 September was still fine, so we finished off the planned archaeology.

The Maelmin Heritage trial was, frankly, a bit of a disappointment (the free booklet available from the nearby information centre in Milfield village is much better). The trail starts with the best bit: a full scale reconstruction of the nearby Milfield North henge (the “henge” being the ditch and bank earthwork, not the wooden posts).

A reconstruction of Milfield North henge.  

 My shot unfortunately just clips the right hand entry post and its carvings: 

a feature of using a smart phone in bright sunlight and 

not being able to see the screen well enough.

Then came a rather short walk round a field containing a reconstructed Dark Ages house, and (the remains of) a reconstructed mesolithic sunken round hut.

The traffic noise from the nearby road during this walk made the silence of the previous day’s Neolithic rock art even more precious.

Next we drove to Yeavering Bell hill fort (incorporating a scenic but unplanned detour, having turned the wrong way out of Milford, and not noticed for a few miles). After looking up at it and estimating it would probably take us about five hours to get to the top and back down again, and noting that we weren’t equipped for that (either in kit, or physically!), we admired it from the bottom.  Google maps have a great view from the air.

So we moved on to “Duddo Four Stones”, which involved just a one hour round-trip walking up from the road. Despite its name, it has five large stones (one stone was re-erected after the site had been named in the 19th Century, and some now use the newer name of "Duddo Five Stones", but that's boring), and there were originally seven.

The stones are easily visible on the horizon, but the path takes a detour around the edge of the fields.

The sign says “Please keep to the footpath”. That’s the footpath, ploughed up, under water. On the way to the circle I tried to keep off the field, along the fence, but it was very slippery, and I went ankle deep into the water (much to the disgust of my 3-day old shoes!). On the way back, I walked round the other, more accessible, side of the puddle.

Duddo Four Stones. Count 'em.

The afternoon was taken up with a pleasant drive around the edge of the Northumberland National Park, down to our final B&B. We stopped off to have a look at a bit of Hadrian’s Wall, with a plan to see more later.  (I am informed by the archaeologist in the party that Hadrian's Wall doesn't count as archaeology: it has a date from contemporary records, so it's history.)

Hadrian’s Wall, with sentry post

 Also, goodbye sunshine, for the next couple of days.

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unconventional identity

I'm just back from a wonderful week in Orleans, at the Unconventional Computation and Natural Computation conference, and associated specialist workshops. Interesting people, fascinating science, good weather, great food: what more could you want?

Here's the semi-obligatory photo from my hotel window, with the cathedral visible in the distance (oh, the bells! the bells!):

As well as the packed science programme, there was the customary conference event.  The conference organisers spoiled us with a choice: a visit to Chambord Castle, or kayaking on the Loire.  Unsurprisingly, I chose the castle.  Very impressive, with an excellent guided tour giving us all the history, from its original use as a hunting lodge, to the bullet holes from WWII.

It's difficult to know how much to believe on these tours.  We were told that eating with a fork was introduced, because it was needed to get past the ruff worn around the neck. It sounds no sillier than the reasons behind any other piece of etiquette, but I can find no evidence for the claim.  The web seems quite happy to credit Catherine de Medici with introducing both the table fork and the ruff to France, but doesn't connect the two, in fact claiming that the fork didn't catch on for a while. Ah well, it's a nice story.

My favourite bit of the castle was the four storey double helix staircase, allegedly designed by Leonardo da Vinci:

This trip was followed by a walking tour of Orleans itself, which seemed to involve a lot of different statues of Joan of Arc.

several statues, of varying size

Our guide told us that all these statues depict Joan of Arc wearing a dress, because it used to be thought wrong for a woman to wear "boys clothes", as she actually did.  Why revere someone for saving you, yet deny what they actually did?

One of the things on the tour that was not a statue of Joan of Arc was Joan of Arc's house.  Except that it wasn't actually her house, she only stayed there; also, the original was destroyed in WWII, and later reconstructed, but at a different size.  It reminded me of the story of "my grandfather's axe". Identity is a slippery concept.

The availability of cheap and plentiful smart-phone photography changes what I snap, too.  As well as the obvious statues, vases, furniture, stair cases, carvings, and other typical touristy shots, I also photographed the timetable at the tram stop:

I didn't snap it (only) because it's a nice example of a stem-and-leaf plot, but because I actually wanted a copy of the timetable, for my trips back-and-forth between the conference venue and the city centre. I was accused by my colleagues of taking the most boring tourist photograph ever.  And then one of them photographed our restaurant receipt, for their expenses claim...

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citation patterns

An academic's contribution to the community is made through publications.  And so we obsessively keep good records of what we have published, and neurotically check out if anyone has noticed.

To this end, I’ve been playing around with Google Scholar, tidying up my auto-generated publications list there. Although I still maintain my own publications page, this separate one is a useful resource, mainly because it includes citation counts and links.

Citation links are good for more than justegoboo and feeding neuroses, honestly! Citations indicate other authors who find my work relevant to them, so it's very likely that their work is interesting and relevant to my own research. It makes sense for me to check them out, and then also check out the other papers they reference, and also their citations, to see if there’s something interesting and relevant to me. Although it is a bit easy to get sucked into a never-ending death-spiral of link following: there’s just too much interesting stuff.

That's the beauty of Google Scholar.  it doesn't just have a list of my papers (a task I can do myself with relatively little effort); it also auto-generates links to citing papers (a task that would be ridiculously time-consuming to do myself).

More than that, it also provides neat little graphs of citations per year. These are quite interesting for publications that are several years old, where patterns have had time to emerge.

The typical pattern shows a peak a few years after publication, then a tail off into obscurity.

Slightly more gratifying is the pattern of a peak, followed by a drop, but then carrying on bumping along at about the same rate.

But the weirdest citation pattern must be to a paper written during my PhD, published nearly 30 years ago. It caused barely a ripple when published (I comfort myself that there was no Web in those days, and hence restricted access to it). But then there was a second (modest) peak of citations after about 15 years, followed by a drop-off. And then there was a third peak, starting more than two decades after publication.

Clearly, a paper ahead of its time!

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tracking down mad dancers, eventually

So, I was looking for the source of the quotation “Those who dance appear insane to those who cannot hear the music”. Googling, everyone says it's Nietzsche, but of course, hardly anyone gives a source. One suggestion I did find was that it comes from The Birth of Tragedy (originally written in 1872), and helpfully included a fairly substantial quotation.  I couldn’t find a source that exactly matched the provided snippet, but I did find one very close:

In the German Middle Ages under the same power of Dionysus constantly growing hordes waltzed from place to place, singing and dancing. In that St. John's and St. Vitus's dancing we recognize the Bacchic chorus of the Greeks once again, and its precursors in Asia Minor, right back to Babylon and the orgiastic Sacaea.
     There are men who, from a lack of experience or out of apathy, turn mockingly away from such phenomena as from a "sickness of the people," with a sense of their own health and filled with pity. These poor people naturally do not have any sense of how deathly and ghost-like this very "Health" of theirs sounds, when the glowing life of the Dionysian throng roars past them.

Friedrich Wilhelm Nietzsche: The Birth of Tragedy, NuVision ebook, 2004

However, while tracking this down, I found a different translation:

So also in the German Middle Ages singing and dancing crowds, ever increasing in number, were whirled from place to place under this same Dionysian impulse. In these dancers of St. John and St. Vitus, we rediscover the Bacchic choruses of the Greeks, with their early history in Asia Minor, as far back as Babylon and the orgiastic Sacaea. There are some, who, from obtuseness, or lack of experience, will deprecate such phenomena as "folk-diseases," with contempt or pity born of the consciousness of their own "healthy-mindedness." But, of course, such poor wretches can not imagine how anemic and ghastly their so-called "healthy-mindedness" seems in contrast to the glowing life of the Dionysian revellers rushing past them.

Friedrich Wilhelm Nietzsche, The Birth of Tragedy. In Albert Hofstadter, Richard Kuhns, Philosophies of Art and Beauty: Selected Readings in Aesthetics from Plato to Heidegger, University of Chicago Press, 1964 (p501) (translation, Clifton P. Fadiman, 1927)

And yet another one:

In the German Middle ages, too, ever-growing throngs roamed from place to place, impelled by the same Dionysiac power, singing and dancing as they went; in these St John's and St Vitus' dancers we recognize the Bacchic choruses of the Greeks, with their pre-history in Asia Minor, extending to Babylon and the orgiastic Sacaea. There are those who, whether from lack of experience or from dullness of spirit, turn away in scorn or pity from such phenomena, regarding them as `popular diseases' while believing in their own good health; of course, these poor creatures have not the slightest inkling of how spectral and deathly pale their 'health' seems when the glowing life of Dionysiac enthusiasts storms past them.

Friedrich Wilhelm Nietzsche: The Birth of Tragedy and Other Writings, Cambridge University Press, 1999 (translation, Ronald Spiers), pp17-18 

One thing that struck me was the sheer variety in these translations. Just pulling our a single phrase (let's take one that has something to do with the original search), shows the great variety of translations possible:

1. under the same power of Dionysus constantly growing hordes waltzed from place to place, singing and dancing 
2. singing and dancing crowds, ever increasing in number, were whirled from place to place under this same Dionysian impulse 
3. ever-growing throngs roamed from place to place, impelled by the same Dionysiac power, singing and dancing as they went 

While we have hordes waltzing, crowds whirling, and throngs roaming, they are all nevertheless uniformly “singing and dancing”. Similarly with the final phrase:

1. when the glowing life of the Dionysian throng roars past them 
2. the glowing life of the Dionysian revellers rushing past them 
3. when the glowing life of Dionysiac enthusiasts storms past them 

Throngs roar, revellers rush, and enthusiasts storm, but all with “glowing life”. It makes one wonder – how much do translators read earlier translations, how much do they consciously decide to change certain phrases and orderings, and why they leave other phrases the same?

But another thing struck me, which was more relevant to my original quest: although close, none of these passages seem to capture the full spirit of the original search topic: “Those who dance appear insane to those who cannot hear the music”.

A link from that original helpful site took me to a discussion about the source being Henri Bergson. The Bergson quote is given in the original French, and in translation, as

• Il suffit que nous bouchions nos oreilles au son de la musique, dans un salon où l'on danse pour que les danseurs nous paraissent aussitôt ridicules
• “It is enough for us to stop up our ears to the sound of music, in a room where people are dancing, in order for the dancers to at once appear ridiculous.” 

Henri Bergson, Le Rire. Essai sur la signification du comique, 1900
Henri Bergson, “Laughter, an essay on the meaning of the comic”, 1900 

Note Bergson says “ridicule” (ridiculous), not “fou” (mad, crazy, wild, foolish).   Nevertheless, this looks closer to the quote than the Nietzsche passage.  So I felt satisfied.

However, whilst searching around for an image of "mad dancers" to enliven this large wodge of text, I came across a website containing a copy of Meyer Levin’s The Golden Mountain (1932), which is “a collection of tales of the Eastern European Hassidic Jews”. It includes the tale of “The Mad Dancers”:

a deaf man passed outside the house; he looked in through the window and saw the people whirling about the room, leaping, and throwing about their arms. 'See how they fling themselves about!' he cried, 'it is a house filled with madmen!' For he could not hear the music to which they danced. 

Now, this seems much closer, and I suspect may be the "true" source. I wonder how much each might have been influenced, directly or indirectly, by the earlier publications?

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narrating complexity

Our new interdisciplinary network on Narrative and Complex Systems is having its first workshop, in York.  Yesterday we had a great time explaining to each other what we did, from narrative in fiction, in films, in computer games, to the narrative of complexity and emergence, and trying to discover common concepts.  We finished the day by brainstorming a mindmap:

This process was amazingly helpful in distilling our ideas.  The result, however, is pretty incomprehensible to anyone who wasn't there!

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The Motherland Calls

Scalzi’s latest post on his Whatever blog is a competition result: someone had to guess what monument he was thinking of in order to win a copy of his latest book.

One reader from Norway correctly guessed it was "The Motherland Calls", a statue in Volgograd.

Scalzi provides a picture, and a link to the wikipedia page about the statue.  I looked at the picture, and thought, that’s a cool statue – great pose, lovely and dynamic, and with a sword, too.

But how on earth did anyone guess this answer from all the possible monuments Scalzi could have been thinking of?

I clicked through to the wikipedia page to find out more about it. 

commemorating the Battle of Stalingrad … blah .... Declared the largest statue in the world in 1967 … blah .... prestressed concrete blah …

It wasn’t until I scrolled down the page and saw the plot of “Approximate heights of various notable statues” that I realised what I was seeing, and the significance of "largest statue in the world", however.

It’s as big as the Statue of Liberty including its plinth!  

So I looked back at the main photo and realised that the noise around the base of the statue, which I had barely registered on my first look, is people.

ZOMG!!!  The statue is over 80m tall.  The sword is over 30m long.  It’s amazing.  How is it that I have never come across this before?

And now it’s a little more understandable that someone guessed it.

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Malaga meals

I'm just back from Malaga in Spain, where I was a member of a PhD thesis defence panel.  It was a very interesting thesis, which I enjoyed reading, and I got to meet up with several colleagues, and have lots on good conversation.

And good food, of course. On the Thursday evening, the supervisors and I went out for a "tapas crawl" -- ham and cheese in the first place, anchovies, cod, and tuna in the next, then finishing up at a Moroccan tea shop.  Along the way we passed the Moorish Alcazaba Fortress and Roman Theatre.




Friday breakfast was churros (fried dough) which are eaten after being dipped in thick hot chocolate -- very more-ish.







Lunch was paella and grilled swordfish on the beach, "serenaded" by green parakeets in the palm trees.  The warm sunshine made a pleasant change from the grey and raining England I had left 24 hours earlier, but I did make sure to sit in the shade.




Dinner, after the defence, was a kind of "up market" tapas, in that there was lots of (relatively) small, varied, delicious and ... different ... courses.

1. Pear draped in salmon covered with blue cheese, accompanied by blackberries
2. Ham and honey crepes
3. Cod in a tomato sauce (okay, quite tame in comparison, really)
4. Lamb, goats cheese, and sweet onion chutney
5. Pork and pate rounds with strawberry sauce

There were several of us dining: the panel, the supervisors, and the successful candidate.  Although we cleared the early courses, it just so happened that we all left some of the final one.  And it was the final main course: next was delivered the sweet course.  So, was it coincidence that we all faltered at the planned final fence -- or would they have continued serving new courses for as long as we continued eating?

Oh, and in between all the meals, as well as the defence there were meetings, presentations, discussions ... and coffee.

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The Puppet of Dorian Gray

Puppet Cliff Richard

I was reminded of this by Jo Walton’s marvellous Oscar! post, and in particular her inspired casting of Cliff Richard as "Dorian Grey".

Several years ago we worked out just why Cliff Richard, the “Peter Pan of Pop”, doesn’t age.  Made back in 1966, the film Thunderbirds are Go included a sequence with Cliff Richard and the Shadows, played, of course, by puppets.

To the right we see what the Thunderbirds puppet of Cliff Richard looked like in 1966.

Today, stored in Cliff Richard’s attic, that puppet is now terribly wizened and aged.

Or maybe not.

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Did Twitter Save Bletchley Park?

I've just come out of a fascinating talk by Dr Sue Black and a couple of guys from Bletchley Park, talking about the campaign to save it from terminal decay, and how social media helped.  I'd heard about Bletchley Park, of course (and a visit is on my to do list), and knew of the crucial role it played in WWII, but I wasn't aware of the true scale -- 10,000 people working there during the war, and over half of them women.

One point that fascinated me.  Sue talked of meeting one of the people who broke the code on some of Hitler's personal communications -- and how talking to him about this made the hairs on the back of her neck stand up.  I think we forget how (relatively) recent much important history actually is, how much of it is in living memory, or only one remove. We talk of the "six degrees of separation" between co-existing people.  But it's often a similarly surprisingly small number of links to what we tend to think of as the fairly remote past. Patrick Moore talks of having met Orville Wright and Neil Armstrong.  I've shaken hands with someone who worked for Marie Curie. 

But back to the talk.  We were asked at the end, do we think Twitter saved Bletchley Park?  Well, as Sue said, it's not Twitter, it's all the people on Twitter, who tweeted and retweeted, signed petitions, and raised funds and awareness.  It wouldn't have happened without them.  Twitter is just ("just") the technology that enabled them to do this.  Crowdsourcing is powerful, but I think it's safe to say that without Sue's input specifically, Bletchley Park would not be where it is today.  Kudos.

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modelling reality

I first came across the difficulty of modelling reality when I designed a database for my books. This was back on the early 1980s when I was a physicist, and had barely even heard the word "database" before I got ViewStore for my BBC Micro. What's a book? Easy, you might think. But what about Ace Doubles? (two novels in one binding). Or a novel in three volumes? Or the same book with a variant title? Or a new edition? Or a translation? Or an abridgement? Or a book published over several editions of a magazine? Or...

The next big realisation was alphabets. In the 1990s I was involved in the international standardisation of the Z formal specification language. We needed to standardise the character set, which included lots of mathematical symbols. And our Japanese collegues wanted non-Latin alphabets. How hard could it be to allow different alphabets? So I went off to read the Unicode Standard. Oh.

I was remined of these issues when I saw a post by Charlie Stross discussing the post "Falsehoods Programmers Believe About Names" by Patrick McKenzie. People's names are difficult to model.

So is time. Different calendars. Calenders with negative and positive years, but no year zero (which is why some people ended up celebrating the 2500th anniversary of the Battle of Marathon a year too early). Changing calenders from Julian to Gregorian -- give us back our 11 days (of tax payments, that is). Changing calenders at different times in different countries. Leap years. The algorithm for leap years (and the difference between the Julian and Gregorian algorithms). The argument about whether the year 2000 should be a leap year. Time Zones. Changing time zones. Summer time (aka daylight savings time). Summer time coming and going at different days in different countries. Double summer time. Leap seconds. And so on.

One of the comments in Charlie's post references "Gay marriage: the database engineering perspective", a post with an interesting analysis of marriage database design (ignoring the name problem), and how some designs make changes harder than they need to be.

Notice the continual use of "ids" in that post. Names (even if we decide how to model them adequately) are not unique, and so are not suitable for an identifier. What properties might make a good unique identifier? I recall hearing of a new police database that used "Surname, initial, date of birth" as a unique id. The story goes that this database was installed a few days before the Kray twins were arrested...

In fact, no attribute is immutable, and so should not be used in such an identifier. The same person who told me the Kary twins story also told me of the problems a hospital had in assuming that the "sex" entry was immutable when they did their first sex-change operation.

Wait a minute. No attribute is immutable? What about "date of birth" (dob)? How can that change? Well, remember this database information is a model of reality, not reality itself. Models can have errors. The dob might have been mis-entered, or been lied about (when my maternal grandmother died, the family discovered from her birth certificate that she was 10 years older than she had let on to her children), or it might simply be unknown.

So ... if modelling designed (social) reality is this hard, why are we surprised that it is hard to model the natural world? If our own names, dates, whatever, refuse to fit some neat classification system, why should biology, geology, astronomy? Is a virus alive or not? Is something a separate species or not? Is Pluto a planet or not? When reality doesn't fit our classification, the fault lies not with reality, but with the classification system.

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A History of Celtic

BBC4 (the new BBC2) is currently showing a four part series "A History of Celtic Britain", presented by Neil Oliver, he of the delicious Scottish accent, and of the permanent crick in his neck as he strides along addressing comments to the camera just behind his left shoulder. I love the awe and excitement with which he fondles prehistoric artefacts; I love somewhat less the Just So Story feel to the "wholesale returns of conjecture out of such a trifling investment of fact" that follows discovery of some fragment of bone juxtaposed with some fragment of rust. (We play the game of coming up with different "plausible" explanations of why someone was buried with three spears, or curled up with a mirror, or whatever.)

We record this series so that we can watch it at the weekend. Our PVR truncates the title to "A History of Celtic". This might not seem so odd, except that "Celtic" by itself refers to a football team, and is pronounced with a soft C ("Seltick"), whereas in "Celtic Britain" it is pronounced with a hard C ("Keltick"). Hmm.

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