The Category Seminar in Sydney

There has been a continuous series of category theory seminars in Sydney since 1970, and the 40th birthday is coming up. It was a crucial seminar in my scientific career, though I haven't been a part of it since around 1998. I owe much, in particular, to Max Kelly and Ross Street, and to the many visitors we had to Sydney.

I have not been able to determine the exact date of the first seminar, held at Macquarie University, but it was probably 23rd September 1970. The first date for which I have notes of a lecture in 7th October 1970:

Mathematics and computer science

I haven't written much lately since we have been travelling. Now I am working on a paper and I am faced once more with the difficulties of working between two fields with different cultures, mathematics and computer science. As I have mentioned elsewhere I worked as a mathematician for 20+ years and then as a computer scientist for 20 years. Perhaps it would be more accurate to say as a mathematician working on computer science for the last 20 years, since the first years have a more profound effect. However my direction really changed around 1990 and I see mathematics differently now.

I want to make a series of observations about this experience as they occur to me, not in any particular order. I will collect them all in this post even though I write them over time.


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Clive Selwyn Davis, 15 April 1916 – 29 October 2009

I am rather out of touch with Australian mathematics and so I have just found out by chance that my MSc supervisor Clive Davis died in October last year. There is an obituary in the Australian Mathematical Society Gazette.
I learnt number theory from him, and remember well "the clarity, vigour and high standard of his lectures. His handwriting on the board was immaculate, and his brief
dictated final summary of each lecture was much appreciated." (quote from the obituary)
I wrote a Master's thesis on continued fractions in 1966 with him, and eventually even wrote a small book on number theory.
At that time, if I remember correctly, the first PhD in mathematics at the University of Queensland had yet to be awarded, so I went to Bernard Neumann's department at the ANU in Canberra, and changed direction, with Hanna Neumann as my supervisor. I had considered continuing number theory with Kurl Mahler, but my impression was that he was not very keen on having students.