Turing centenary

The Alan Turing Year was celebrated worldwide in 2012. Multiple Turing events were held in several cities. I attended quite a few of those events myself and audio recorded the speeches. My objective here is to compare and contrast claims that computer professionals, historians, and others have made about Turing and our field.

Reading Assignments at Siegen University


30 November 2017


Dear Media Students,

Thank you for attending my class today. Please prepare the following two assignments for 14 December 2017. You will be asked to actively participate.



Read James Somers's `The Coming Software Apocalypse,' which appeared in The Atlantic on 26 September 2017.


Hopcroft and Ullman


24 October 2017

Is the history of computer science solely a history of progress? I don't think so. Judge for yourself by reading the present post in which I scrutinize the famous textbooks of John E. Hopcroft and Jeffrey D. Ullman.

Quotes from 1969 and 2007

I start by comparing the following two quotes. The first quote comes from Hopcroft & Ullman, 1969:


Jos Baeten


June 2015

On June 3rd, 2015, Jos Baeten and Liesbeth De Mol each gave a lecture for my Master class "Logic and Computation." I requested my students to write a one-page summary on either Baeten's or De Mol's talk. Baeten talked about reactive Turing machines, De Mol gave a presentation on the history of the Church-Turing thesis.

My student Bobby Vos wrote the best summary, which was on Jos Baeten's talk. I am happy to reproduce it below with Bobby's permission. Enjoy!


Knuth and P = NP


December 2014

New book: Algorithmic Barriers Falling: P=NP?  Just appeared!

From the preface:

The official site of ACM Turing Award winners describes Donald E. Knuth as the rare theoretician who writes many lines of code every day. His main life goal from the 1960s onwards is, in a nutshell, to nail the costs of computation down to the last penny.


A Turing Tale


21 August 2014

This post contains extra information about my CACM article `A Turing Tale' (October issue, 2014), specifically regarding particular book chapters and page numbers for the source citations appearing in my article.

Below, I present fragments of my article along with precise source citations which were omitted due to editorial styling conventions.

In my section entitled "Hodges":


Towards The Origins of Computational Complexity

One of my students at Utrecht University reflected during the spring of 2014 on the origins of computational complexity. She has given me permission to publish her beautiful essay here (anonymously).

Her chosen research topic is a difficult one to address. But, by presenting a pluralistic account in which she lets her historical actors tell the story (Cobham, Hartmanis, Rabin, Blum), she has succeeded in conveying technical information to an audience that need not be versed in complexity theory per se.

Prime Numbers and Turing


October 2012

In his beautifully written book The Music of the Primes [1], Marcus du Sautoy presented a history of mathematical investigations into the behavior of the prime numbers. Can one predict when the next prime number will occur? Is there a formula that could generate prime numbers? Du Sautoy entertained such questions by discussing the work of several great mathematicians of the past, including Gauss, Riemann, and Turing.


Difficulties of Writing About Turing's Legacy


3 September 2013

My mentor, the historian Gerard Alberts, has advised me repeatedly during the past four years not to use technological concepts, like `program', `compiler', and `universal Turing machine', as subjects of my sentences. Instead, I should use historical actors. For example, I should not write

During the 1950s, a universal Turing machine became widely accepted as a conceptual abstraction of a computer.

Instead, I should write

By 1955, Saul Gorn viewed a universal Turing machine as a conceptual abstraction of his computer.



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