# Alan Turing: life, intuitions and works of the genius and father of AI

Madras, early 20th century. The British Empire dominates India. Julius, an Oxford History graduate, served as a colonial administrative clerk in the Indian Civil Service. Together with his wife Sara, born in Madras and daughter of an engineer, they are expecting their second child. Given the political instability of the period, they decide to return to England and have their baby born in London. On June 23, 1912 in the Maida Vale district of north London, the newborn makes its first cry. **Julius Turing and Ethel Sara baptize their baby with the name of: Alan Mathison Turing** . Subsequently, after moving to the South of England, on the southern coasts of East Sussex, a few months apart from each other, Julius and Sara return to India, but given the precarious health conditions of little Alan the parents decide to leave the two little brothers, John and Alan, in London, in foster care.

## Custody of Alan Turing

**Alan suffers from rickets, a childhood-onset skeletal disease** . So his parents prefer to avoid a long and stressful journey to India, leaving him in the care of an elderly couple from Hastings in East Sussex. But not only that, later, back in England, the mother discovers that Alan also suffers from mental disorders. Managing to suddenly switch from tears to anger and vice versa. But despite these personality disorders, he describes him as a sociable, intelligent and somewhat likable child.

## Alan Turing personality

**From an early age, even before learning to read, he showed an interest in numbers and a lively mind** . His passion for science, but also for geography, push him to experiment and invent. But he didn't just love studying, Alan also enjoyed cycling and running. This passion for physical activity will remain for the rest of his life. Alan had a childlike personality even as an adult. He wasn't vain and didn't pay much attention to his appearance almost to the point of appearing scruffy. At twenty-two she had a teddy bear gift as a gift and curiously she knew the spell of the evil witch of Snow White by heart. Among the many extravagant behaviors, there was that of hiding his teacup or chaining it with a padlock to prevent it from being stolen.

## Alan Turing Studies

After returning to live with his mother, at the age of thirteen he enrolled at Sherborne School (a school which later also had the actor Jeremy Irons and the writer John le Carré as students). **During his studies he will immediately demonstrate a propensity for mathematics and also a great ability to perform mental calculations.** And it is precisely here, in the last years of the course that Turing falls in love with another collegiate, who died prematurely of tuberculosis. Thanks to a scholarship in 1931 he enrolled at King's College, Cambridge to study mathematics and where in 1934 he graduated with honors.

In April 1936 he published an article "On computable numbers", in which he introduced the Turing algorithm and concept of machine. **In this article he demonstrates that there is a class of problems with no algorithmic solution and that it plays a fundamental role in the theory of computation** . In 1936 Turing entered Princeton University (USA) where in 1938 he obtained a doctorate in mathematics. His article was noticed by one of the leading scientists of the time, John von Neumann.

## The Turing Machine

The Turing machine is a mathematical model used to study the foundations of theoretical computer science. **A Turing machine is an abstract executor capable of performing only elementary operations** , and is called abstract because it is imagined with an infinite memory and without execution times, computation times. This makes it possible to abstract from the physical executor (computer).

This ideal performer is what is technically called a computational model. This abstraction from the computer allows us to move from a physical to a mathematical environment. The Turing machine is a classic computational model but not the only one, perhaps the best known. It goes without saying that this abstraction does not possess the same characteristics that one might expect from a modern computer.

### Complexity and Calculability

Although it may seem like an excessive simplification, this classic model of theoretical computer science is used to describe concepts and properties of the theory of complexity and of the theory of computability. Theories that study which problems can be solved automatically and which cannot. In summary, while the theory of computability **tells us which problems are worth trying to solve and which are not because they are unsolvable** and if there are solving algorithms. The Theory of Complexity is useful for understanding the intrinsic complexity of problems. That is, given a problem, how complicated is it to solve? And how many computational resources are needed for a specific solution of a problem?

### What is the Turing machine and how is it made?

A Turing Machine consists of an unlimited tape divided into cells that we can basically define as memory. In each single cell it is possible to write symbols belonging to an alphabet of that machine. The information contained in each cell must be finite, a single symbol, letter or number, but not a string of arbitrary length. The magnetic tape is therefore the place where our executor receives the input data and writes the intermediate calculation data.

A mobile head whose task is to read, write or erase symbols of the cell on which it is positioned. This head can be compared to a processor and is governed by a program (a series of instructions) which tells the machine how to behave according to the configuration it is in and the symbol it finds, i.e. it can: read, write, erase or move one position to the right or left at a time.

In summary, a Turing machine consists of an unbounded tape, a head, and a sequence of instructions. Perhaps surprising to know that such a simple conceptual model is, in theory, capable of performing any kind of mathematical operation. **The latest or fastest computer, in theory, fails to do anything more than this simple conceptual object. It just manages to do it faster.**

## Theoretical computer science is born

**Turing is responsible for the creation of a formalism capable of structuring the concept of algorithm** . By using the machines he defines. Algorithms were nothing new, but their rigorous formalization was. In this way he demonstrates the power and limitations of the algorithm concept. Turing worked on the decidability problem of arithmetic, simultaneously but independently, by another American mathematician, Alonzo Church. The two introduce two different concepts of computability. (Lambda) ʎ-calculus a formalism, later, widely used to study the semantics of programming languages. Turing immediately realizes that Church's ʎ-calculus is completely equivalent to the formalism of his machines.

Hence the Church-Turing thesis. It supposes the possibility of developing an algorithm concept also with methods other than the Turing machine and ʎ-calculus or any other formalism. But this new concept of algorithm will have to have at most the same computing power as abstract machines. It is surprising to note how such elementary theoretical structures hide such strong calculating power. Among the many formalisms there are all the programming languages developed in the 1900s. Thanks to the computing power of his machines, Turing also answers the question of decidability posed by David Hilbert. In short, it asks: **Is it possible to write an algorithm that by examining another algorithm with its input is able to determine whether it will terminate without ending up in an infinite loop and a termination point?**

## Dark times. War

1939, the beginning of the Second World War, Turing is recruited by the British army at Bletchley Park as a cryptanalyst to decipher German codes. With the help of the first electronic computer, which is given the name Colossus, built under the supervision of Turing, and which enters service in 1943. In 1944, Turing was commissioned to develop a computer, the Automatic Computing Engine ( ACE), able to compete with von Neumann's American EDVAC project. In 1947, Turing conceived the idea of computer networks, the concept of software subroutines and also described the basic ideas of neural networks.

## The end of the war and the last years of Alan Turing

Alan Turing continued to design computers according to von Neumann's architecture. The Mark I was finished in 1948 before EDVAC. Also designing its programming language. Another of Turing's fields of research was artificial intelligence, a discipline born from the article entitled "Computing Machinery and Intelligence" published by Turing in 1950.

The first sentence of this article is very famous: "I propose to consider the following question: Can machines think?" Turing later proposed a method called the Turing test for determining whether a machine can be intelligent. Turing's career came to a sudden halt after he was indicted and convicted of unethical behavior at the time.

**Two years after Turing's conviction, he committed suicide by eating an apple spilled with cyanide** . Apple found next to his corpse and what if he crosses the path of that verse that as a boy he knew by heart: the spell of the evil witch of Snow White.

The article Alan Turing: life, intuitions and works of the genius and father of AI was written on: Tech CuE | Close-up Engineering .