Young Birds on Reading University Lakes

The young Egyptian goose has now got its adult plumage.  A week ago it was still looking rather scruffy with patches of brown adult feathers sprouting out of the grey fluffy down.  Now it looks very smart.

A coot nesting on the large lake had 6 tiny chicks yesterday afternoon.  They seemed to overflow the nest and whenever one of their parents came back to the nest one or two of them would swim out to meet them.  These more adventurous ones will surely get more food than the timid ones that stay at home, but they are also more likely to fall prey to the pike that lurk under the surface.  Adult coots are normally fairly territorial but Zoe and I were surprised to see one of the parents attacking a swan that drifted too close the nest.  The swan seemed to take heed of the warning and moved off, however, a bit later we saw the same swan chasing off some Canada geese for no apparent reason.

Coots and Swans on the Kennet

The coot nesting under the bridge at Gunter's Brook has one quite large chick; the one nearer to King's Point had two smaller chicks but now seems to have only one.  The swan nesting near HomeBase has two small fluffy grey cygnets.

Eric Hehner on Model-Checking

A year or so ago I came across the following passage which nicely highlights the limitations of using model-checking to verify that programs meet their specifications:

There is an approach to program proving that exhaustively tests all inputs, called model-checking. Its advantage over the theory in this book is that it is fully automated. With a clever representation of boolean expressions (see Exercise 6), model-checking currently boasts that it can explore up to about 10^60 states. That is more than the estimated number of atoms in the universe! It is an impressive number until we realize that 10^60 is about 2^200, which means we are talking about 200 bits. That is the state space of six 32-bit variables. To use model-checking on any program with more than six variables requires abstraction; each abstraction requires proof that it preserves the properties of interest, and these proofs are not automatic. To be practical, model-checking must be joined with other methods of proving, such as those in this book. (Eric C. R. Hehner, A Practical Theory of Programming, 2nd ed, 2002)

Incidentally, you can find an online copy of Hehner's ground-breaking book at http://www.cs.toronto.edu/~hehner/aPToP/.  Unfortunately, many people have not yet noticed that the ground has been broken and seem to be busy trampling it flat again!

The Adventure of English by Melvyn Bragg

Based on a series that Bragg made for television, this book is a history of the English language over the past 1500 years.  It starts in Friesland in north Holland, where the local language even now has many words that uncannily similar to their English equivalents.  Around 500AD, the Frieslanders as the Angles, crossed the north sea and colonized what became East Anglia, Mercia and Northumbria.  Over the next few hundred years their language gradually became the dominant language of 'Engalond'.  From about 800 onwards English faced challenges from the Danish and Viking invasions, but somehow the language survived, absorbing many new words in the process - a lot of northern dialect words date back to this time.

Then came the Norman invasion.  I had not realized how much England was really just a French colony for the 300 years following 1066:  all of the English ruling class and landowners were replaced by French speakers and English remained the language of the lower classes only re-emerging as a language fit for government after the Black death weakened the feudal system in 1349.  And it wasn't until Henry V that you again get a king whose first language was English.

The story goes on through Chaucer, Tyndale (and his subversive English bible) to Shakespeare.  Bragg paints a picture of Shakespeare and his contemporary writers competing with each other in inventing new words and phrases to express ideas: "mind's eye", "salad days", "dog them at the heels", "fast and loose".  I found this angle on WS new and refreshing.

From the 17th Century onwards, English spreads out across the world to America, India, Australasia, the West Indies and splits into many dialects which then feed back new words and phrases into UK English.  Sometimes words lasted longer in the colonies than they did at home: 'dinkum', apparently once Midlands dialect for 'work',  survived in Australia as 'fair dinkum': a fair day's work.

This view of a language as a fantastically detailed patchwork quilt is quite inspiring.  Bragg mentions that as a child he spoke with a heavy accent that was unintelligible to his teachers.  In such cases it was, and still is, common for teachers to denigrate dialects and encourage the children to speak 'proper' English.  Maybe knowledge of the history of the dialect would change the teachers' attitude.  In Bragg's case his dialect contained words from Old Norse, the language spoken by viking settlers over a thousand years ago, and from Romany, the language of horse dealers who have held horse fairs in his home town for hundreds of years.

A Dead Goldcrest

As I was walking along Frimley Road on my way to work I noticed a small greenish lump, no bigger than 2 inches long, lying on the path.  I had walked past it before I realised what it was - a tiny bird.  I stopped, picked it up and immediately recognised it as a goldcrest.  Turning it over showed the characteristic yellow stripe along the top of its head.  It was dead, having probably been hit by a car on that busy stretch of road.  There were no visible injuries to it, but it left some small darkish brown spots, probably dried blood, on my hands.  The feathers on its body were incredibly soft, the slightest breath of air being enough to ruffle them.  I put it down gently under the hedge, so it wouldn't get trodden on.