Mathematician of the week Alan Turing

Alan Turing: 1912 – 1952

Alan Turing was a highly talented mathematician who was born in London in 1912 and by all accounts he was average when he was at school (all the best people are). He was criticized for his poor handwriting and for following his own ideas and methods rather than that of his teachers. How often do we hear that old chestnut from teachers? However whilst he was at his school he managed to win all the prizes in mathematics. (1926).

Now what the teachers did not know that Turing was partaking in a little outside reading and this is where he gained his knowledge at an early age. I think this is evidence of the power of just taking a chair and having a read every now and again.

Let us move forward to 1931 and the young Turing went to Cambridge to study mathematics. He graduated in 1934 and was elected as a fellow of King’s College for work, which helped to prove results in probability theory (central limit theory). So far Turing had just been working in the area of probability. It was 1936 that Turing moved into what would be he foundations of what we now call computer science and he published On Computable Numbers, with an application to the Entscheidungsproblem. It was this paper that Turing introduced us to the “Turing Machine”, (he obviously didn’t call it this) essentially the machine could write or delete a symbol on a tape. In doing so it would be following an algorithm and so change state (start with one result and end up with a different result).

It is now 1939 and with the outbreak of the war Turing moved to Bletchley Park where he was involved in code breaking of the Germans. In doing so he received the O.B.E for his contributions.

1948 and Turing is now in Manchester where he had been invited by Newman. It was here that Turing produced work into computing and decidability. He was elected to the Royal Society of London in 1951 for his early work with Turing Machines.

We can’t have a Biography of the gentleman without a mention of his arrest in 1952 for a homosexual affair he was having. He actually handed himself into the police as has was threatened with blackmail. He offered no defense as he said he was doing nothing wrong (how times have changed for the good).

He was also at this point working for GCHQ. Who due to the circumstances of his arrest stopped his security clearance. We are now in the cold war and the strange circumstances of his death. Turing was conducting an electrolysis experiment and eating an apple (you can see where this is going). He ate half of his apple and died. Upon inspection potassium cyanide was fond on the apple. It was said he knew it was there.

Well that was Turing the father of modern computer science. Apparently he was also a bit of a runner! Good man.

All the usual apologies for mistakes and things like that.

Problem 3

Problem 3: This one is all about counting and choosing

You are trying to escape from a prison (you where framed of a crime you didn’t commit)

A security system uses passwords of the following form.

Two letters followed by two digits. (Letters are a,......, z and Digits are 0, 1, 2,..., 9)

How many different passwords are there?

i). Assume you could have repeats e.g. aa22

ii). Assume no repeats

Problem 2

Mathematician of the week

Pierre-Simon Laplace

1749 -1827

Laplace was born Normandy to a family who were relatively well off for their situation. Father was a merchant and his mother was from a well off farming family. Initially Laplace went to a priory school till the age of 16. He then enrolled at Caen University to study theology (this is becoming a recurring theme in our mathematicians) however during his time there he discovered his talent for mathematics (this keeps on happening too). Credit for this discovery partially goes to his teachers there.

As soon as this talent was discovered he left the university and went to Paris at this point he was only 19. When he arrived in Paris he was introduced to d’Alembert (he is well known for studying differential equations). Laplace was then tutored by d’Alembert and he assisted him in finding work.

 His early work in Paris during the early 1770’s was into difference equations and maxima and minima. He also read papers on these two topics to the Academy during this time. He also tried to gain a position into the Academy and he eventually succeeded in 1773. It was also around this time where he would begin the study of planetary motion, differential equations and probability.

In the next stage of his career during the 1780’s Laplace increased the depth of his results and gained his reputation. However he also considered himself the best mathematician in France which didn’t go down well with his colleagues (even though he was probably correct!) He was also appointed a position in the French army examining cadets and he actually examined a young Napoleon!

A point of note is that in the mid 1780’s Lagrange came to Paris to work with Laplace and although there was a rivalry the two men seemed to get along (obviously for the love of mathematics).

This now brings us to the 1790’s (yeh the French revolution!) and the time when the Academy was suppressed. Laplace then left Paris with his family and he gained a position training school teachers however this position didn’t last for long (his courses were a little advanced). Laplace then returned to the reopened Academy where he presented his nebular hypothesis. This was a modern view of the evolution of the solar system (a large cooling, rotating cloud of gas into what we see now).

In and around 1799 Laplace published some of his greatest work in planetary motion. He was able to prove that he planetary orbits are stable and self correcting. Moving into the 1800’s Laplace began work in probability and again published papers in applications of probability and errors to name a few.

So in summary:

·         Laplace was a very savvy politician and this enabled him to reach some of the positions had during his life.

·         The Laplace equation is named after him (highly important partial differential equation)

·          He was a little arrogant (and why not? He was good!).