Archive for the ‘Uncategorized’ Category

Alan Robinson

September 16, 2016

On August 5, 2016 John Alan Robinson died. In him, a great scientist departed, and I mourn a dear friend. His great discovery was the resolution principle in mathematical logic, a discovery that capped two decades of development. In its turn, it spawned a plethora of new developments in computer programming. It became important enough in Artificial Intelligence to become controversial. (more…)

Wildcat Crypto

May 13, 2016

With his “Pretty Good Privacy” (PGP), Phil Zimmermann launched the era of what I call Wildcat Crypto. Up to that point discussions on cryptology had focussed on whether DES, the US government standard, was secure and whether government involvement in its development might have jeopardized its security. To avoid government involvement, PGP used IDEA as alternative to DES for its bulk encryption. Yet IDEA is a close relative of DES and shares its weakness: small, constant-size blocks. True Wildcat Crypto calls for a radical departure in the form of blocks that are much larger, and moreover, vary in length under control of the key. In this article I trace the relevant history and outline my implementation of such a radical alternative.


IA or AI?

October 9, 2015

I’ve been reading a paper [1] written two decades ago, which itself is an account of events two decades before that. It is Alan Kay nominally writing about the history of a programming language called Smalltalk. I say “nominally” because already by Smalltalk 72, Kay was losing interest in language matters and wanted concentrate on what the language, as part of the computer-as-medium, could do for thought. Along with various other sources of inspiration that led to Smalltalk (Sutherland’s Sketchpad, the Burroughs B220, the Burroughs B5000, …) Kay mentions attending in 1968 the conference presentation by Douglas Engelbart [2] that has since become known as the “Mother of All Demos”.

In 1968, when timesharing by users behind teletype terminals was regarded as avant-garde, Engelbart gave a demo that featured a number of firsts: a screen display for both and text and graphics, interactive text-editing, a mouse. All that was integrated into a fluidly handled medium. Kay gives testimony to the huge impression this made on him: “Engelbart was a prophet of Biblical proportions”.


The H-bomb and birth of the computer, part III: triumph of brains and slide-rules

April 2, 2013

The question that led to von Neumann’s involvement with Edvac in 1944-1945 was whether Teller’s design (the “Super”) for a hydrogen bomb was feasible. The question that von Neumann wanted to settle was whether in Teller’s design a fission explosion causes a self-sustained propagation of fusion in fusible material.

When Eniac was ready for the first trials in December 1945, von Neumann had convinced its owner, the Ballistics Research Laboratory, to give the ultra-secret computation from Los Alamos priority. Only the researchers from Los Alamos, Metropolis and Frankel, had the requisite security clearance to know the subject of the computation. The necessary personnel to help operating the Eniac did not. The problem was finessed by ruling that the equations and the data only were demoted from their lofty top-secret classification. Eniac performed splendidly, all 18,000 tubes working in unison for a sufficient proportion of time to get the computation completed in six weeks.


The H-bomb and the computer, part II: the revolution that almost didn’t happen

April 2, 2013

In spite of the tumultuous development of computers, the architecture in the form of the fetch-execute cycle has remained the same from EDVAC design of 1945 to the present day. And we are used to call this basic architecture “von Neumann machine”. This makes John von Neumann a sort of patron saint of our field.

Not everyone accords this status to the great mathematician who lived from 1903 to 1957. One of my favourite architecture books refuses [5, page 32] to use the term because of the supposedly equal contributions by J. Presper Eckert and John Mauchly. Many of those who do accord full credit to von Neumann for the architecture invoke the name in the pejorative sense of “von Neumann bottleneck” and suggest that the architecture has hindered rather than helped the development of computers.

In this essay I review publications that shed light on the origin of the computer and conclude that it was von Neumann who made the critical contributions in 1944 and 1945. In addition I will argue that von Neumann’s was the basic architecture that propelled the computer along its miraculous trajectory covering three orders of magnitude in size and five in cost and processor speed. Finally I will reflect on the fact that von Neumann was not only an extraordinary genius, but also that he combined in his background a most unusual combination of disciplines — a combination that was essential to the birth of the computer. Without this fortuitous confluence of circumstances the development of computers in the period 1950 – 2000 would not have had the explosive character that we actually experienced. Hence “The Revolution That Almost Didn’t Happen.”


The H-bomb and the birth of the computer, Part I: Edward Teller’s obsession

April 2, 2013

In 1945 the stored-program computer was invented; by 1950 every country wanted computers. None were for sale, so every country was trying to build them. Not just the big players, like the US and Britain; by 1955 computers had also been built in Switzerland, Russia, the Netherlands, Sweden, and Belgium. At the origin of this wave of enthousiasm was J. von Neumann’s prestige and advocacy. In 1945 he had not only been the first to describe how to build a computer in the modern sense, but he was also infused with the conviction that this was nothing less than a new, universal research instrument with the potential of revolutionizing science. As a result he wanted his design to become as widely known as possible, as soon as possible.

How von Neumann got involved in electronic computing will be the topic of the next instalment. Here I first want to recount why he got involved. It had to do with the unholy alliance of science and war.


Scruffies and Neats in Artificial Intelligence

September 11, 2011

In a previous essay [0] I traced the Lighthill Affair to the tension between the scruffies and the neats in Artificial Intelligence. As a reminder the official [1] definition of these terms:

” … the neats — those who think that AI theories should be grounded in mathematical rigor — versus the scruffies — those who would rather try out lots of ideas, write some programs, and then assess what seems to be working.”

For a few lines this is a pretty good characterization. But I think it only scratches the surface. In this essay I will explore the contrast in temperament and attitude that exists along several dimensions and is found elsewhere in science.


From the Chronicles of Scruffy Versus Neat: the Lighthill Affair

February 18, 2011

The 1973 Lighthill Affair was an Affair in the sense of the Dreyfus and Profumo Affairs. And although it was scaled down to teacup size, it was big enough to make it into a textbook published twenty years later:

… the Lighthill Report, which formed the basis for the decision by the British government to end support of AI research in all but two universities. (Oral tradition paints a somewhat different and more colorful picture, with political ambitions and personal animosities that cannot be put into print.) [1]

In this article I will put in print some of the things hinted at here, and elaborate on the issues that have remained topical.


Who Killed Prolog?

August 21, 2010

There are a thousand programming languages out there (Literally, it seems, according to people who actually count such things.) A classification of so many species is bound to be complex and subject to much debate. However messy and controversial things get low down in the classification, let’s have just four branches at the top level. I attach to the name of the class of programming language what I consider to be the first exemplar of the class, in chronological order:

— imperative (1956, Fortran)
— functional (1959, Lisp)
— object-oriented (1972, Smalltalk)
— logic (1974, Prolog)

I take as starting point the fact that three of the four branches are doing well in the sense of having a vigorous following. Compared to these three, Prolog has fallen far behind. This was not the case in the early 1980’s, when Prolog had caught up with Lisp in capturing mindshare of what you could call non-IBM computing (to avoid the vexed term “AI”). Hence the title of this article. As culprit (or benefactor, depending on how you look at it) I identify the Japanese “Fifth-Generation Computer System” project, which existed from 1982 to 1992.


I remember Donald Michie (1923 – 2007)

June 12, 2009

On July 7, 2007 Dame Anne McLaren and Donald Michie died in a car accident. Last time I had met Anne was in the 1970s when I stayed at their house in Edinburgh. Both were launched on scientific careers that were to lead them to positions rivalling each others’ eminence in their respective fields.

The last time I met Donald (henceforth “DM”) was when my wife and I visited him in Oxford in November 2004. He demo’ed the Sophie chatbot system, asking us what we thought of his choice of accent for the speech-generating software. He was intrigued by the way his current choice, labeled “Southern California Trash”, blended with the other personality attributes of Sophie. The stereo was playing DM’s current favourite, “Harper Valley PTA” sung by Jeannie C. Riley, another sassy American female.

Although excited by his current project, DM was depressed by the gloomy British weather; he would depart shortly to spend the winter in Gibraltar. “Gibraltar??”. “Yes, Gibraltar. I trust it will be sunny, and it is British.” In the following pages I have noted, roughly in chronological order, some experiences with this extraordinary man, one of the great pioneers in Artificial Intelligence.