Skip to main content

Once upon and Algorithm - Martin Erwig ***

I've been itching to start reading this book for some time, as the premise was so intriguing - to inform the reader about computer science and algorithms using stories as analogies to understand the process.

This is exactly what Martin Erwig does, starting (as the cover suggests) with Hansel and Gretel, and then bringing in Sherlock Holmes (and particularly The Hound of the Baskervilles), Indiana Jones, the song 'Over the Rainbow' (more on that in a moment), Groundhog Day, Back to the Future and Harry Potter.

The idea is to show how some aspect of the story - in the case of Hansel and Gretel, laying a trail of stones/breadcrumbs, then attempting to follow them home - can be seen as a kind of algorithm or computation and gradually adding in computing standards, such as searching, queues and lists, loops, recursion and more.

This really would have been a brilliant book if Erwig had got himself a co-author who knew how to write for the public, but sadly the style is mostly heavy academic, so the cleverness is rather wasted. Sometimes this comes across in labouring points and at others in spending a lot of effort on what is little more than defining labels for things, rather than providing useful information and context for the reader. It's not that there's not a lot of good material in there, just that it's hard work to dig it out, where I'm sure the whole idea of using the stories was to make it more approachable.

Part of the problem is that the stories themselves don't always work very well as an analogy for what's happening in the computation. So, for example, in the section dealing with sorting he comes up with the task of sorting the tasks and places that Indiana Jones needs to deal with to find the Lost Ark. The unsorted list includes the likes of: disc, sunbeam, Marion and Nepal. The algorithm used involves finding the 'smallest' element... which somehow we are supposed to instantly see is Nepal. Using numbers would not have been so well-linked to the story, but at least it would have made some sense to the reader.

Perhaps the low point is the section that uses a part of the song 'Over the Rainbow' (giving us a tenuous story connection to The Wizard of Oz) to examine language and meaning. If you aren't familiar with musical notation, I'm not sure it's a very helpful analogy... and if you are, some of the ways it's used (particular the assertion of what bars are for) doesn't entirely make sense.

I was a professional programmer for a number of years, but without a computer science background. So I was very familiar with how to do this stuff, but knew nothing of the theory behind it. As such, I found the content of the book really interesting - and the story idea should have made it doubly brilliant - but the execution meant that it didn't deliver anywhere near as well as it could have. Even so, there's a lot to savour, and it's definitely worth persevering to get a feel for why computer programs involve far more than just 'cutting code.'



Review by Brian Clegg


Popular posts from this blog

The Feed (SF) - Nick Clark Windo ****

Ever since The War of the Worlds, the post-apocalyptic disaster novel has been a firm fixture in the Science Fiction universe. What's more, such books are often among the few SF titles that are shown any interest by the literati, probably because many future disaster novels feature very little science. With a few exceptions, though (I'm thinking, for instance, The Chrysalids) they can make for pretty miserable reading unless you enjoy a diet of page after page of literary agonising.

The Feed is a real mixture. Large chunks of it are exactly that - page after page of self-examining misery with an occasional bit of action thrown in. But, there are parts where the writing really comes alive and shows its quality. This happens when we get the references back to pre-disaster, when we discover the Feed, which takes The Circle's premise to a whole new level with a mega-connected society where all human interaction is through directly-wired connections… until the whole thing fails …

Everything You Know About Space Is Wrong - Matt Brown ****

What we have here is a feast of assertions some people make about space that are satisfyingly incorrect, with pithy, entertaining explanations of what the true picture is. Matt Brown admits in his introduction that a lot of these incorrect facts are nitpicking - more on that in a moment - but it doesn't stop them being delightful. I particularly enjoyed the ones about animals in space and about the Moon.

Along the way, we take in space exploration, the Earth's place in space, the Moon, the solar system, the universe and a collection of random oddities, such as the fact that Mozart didn't write Twinkle, Twinkle Little Star. Sometimes the wrongness comes from a frequent misunderstanding. So, for example, Brown corrects the idea that Copernicus was the first to say that the Earth moves around the Sun. Sometimes there's some very careful wording. This is used when Brown challenges the idea that the Russian dog Laika was the first animal in space. What we discover is that, i…

Dark Matter and the Dinosaurs - Lisa Randall ****

I did my PhD in galactic dynamics - which is an awkward subject when people want to know what its relevance to the 'real world' is. So I was excited when Clube and Napier's book The Cosmic Serpent came out, around the same time, because it provided me with a ready-made answer. It argued that the comets which occasionally crash into Earth with disastrous results - such as the extinction of the dinosaurs - are perturbed from their normal orbits by interactions with the large-scale structure of the galaxy.

I was reminded of this idea a few years ago when there was a flurry of media interest in Lisa Randall's "dark matter and the dinosaurs" conjecture. I was sufficiently enthusiastic about it to write an article on the subject for Fortean Times - though my enthusiasm didn't quite extend to purchasing her hardback book at the time. However, now that it's out in paperback I've remedied the situation - and I'm glad I did.

Dark matter is believed to exi…