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Ib Sorensen – In memoriam


It comes as a terrible shock to learn of the death of Ib Sorensen, who has been associated with the Department for over 30 years.   The following tribute was given at Ib’s funeral by the Head of the Computer Science Department, long-time colleague and friend, Bill Roscoe.


I have been asked to say a few words about Ib’s work. 

He was an inspiring person to work with and many have happy memories of him as a colleague.

I witnessed a lot of his working life since we both arrived as research students at the Programming Research Group, as the department then was, at the end of the 1970’s, he about 6 months after me.

I was a conventional doctoral student straight out of my undergraduate studies, while he moved from the start of an academic career in Aarhus.   I think he had much more idea what lay ahead than I did.

The department was very small then with two academics, a few visitors and research staff, and maybe a dozen students like us.   Its research had just been given a new dynamism by the arrival of Tony Hoare. Arriving at about the same time were Bernard Sufrin and Jean Raymond Abrial.  Ib joined them in the team that developed Abrial’s ideas for the specification language Z and started applying it to real problems.    Z was and is hugely influential in the world of “formal methods” or formally-based software engineering.  It led, for example to B – another development instigated by Abrial – to which Ib devoted a good deal of his subsequent career.

Z caused a good deal of confusion on the pronunciation stakes.  The English and even Scots and some French call it Zed.  The Americans call it Zee and get confused when we correct them Zed.  But Ib had his own distinctive pronunciation:  Zet.    I am sure many of us can hear him say that.

Ib was at home amongst real professional software engineers in a way that not many academic computer scientists are.  One thing that impressed me early on was his ability to talk the talk with managers and persuade them of the merits of what we were doing.   He managed to sound authoritative in any company.  He usually was.

The first really big application of Z was to the CICS system in IBM, software of truly global size and significance.  Ib was in at the start of this work and played a major role in it.  Its success – internationally recognised then and now as one of the major achievements of formal methods – owed a great deal to him.  It won the department one of its two Queen’s Awards for Technological Achievement – in 1992.

He became a lecturer – alongside Richard, Bernard and me—in 1983.  In an instant we trebled the department.   Of course being a lecturer he had to lecture, and much of this was concentrated on teaching industrialists such as those from IBM.  This laid the initial foundations for what led to the Software Engineering Programme subsequently set up by Jim Woodcock and now led by Jim Davies.

People remember the warmth of his lectures and his willingness to tell series of wise anecdotes to his audiences.

Before very long he was head-hunted into BP and worked there for a number of years, but never lost touch with us.  Eventually he took the entrepreneurial bull by the horns and set up B-core with Dave Nielsen, building the B-toolkit, promoting and consulting with it and continuing to promote the use of formal methods.   This was a brave move since formal methods has been a notoriously difficult area to turn into a successful business plan.  But B-core operated out of Harwell for many years.   

The ideas of B, in which a specification is developed into correct code, correspond to the modern label of “model driven development”, and it was under this label that Ib created a B-based technology with Jim Davies and the Crichtons.  This is called Booster, and develops web-based database systems from models.  

Developing this technology in the department led to it being used widely to create our admin systems and departmental web pages.  Ib spent a significant amount of time and effort improving the central university’s IT, a surreal experience indeed.

Gradually he became central to the existence, not only of the Software Engineering Programme, but also of the department as a whole. He was central to our public profile and smooth operations.

Having employed him through B-core for many years to lead the development of these systems, I decided to employ him properly a few years ago.  So his career, in a sense, came full circle.  He found himself in a department in which he was surrounded by a few people he had known for many years but by many more to whom he was new.  

He really was the perfect person to work with.  He has a unique place in my heart and I am sure that all his colleagues think the same.  Such a professional, open and friendly person, he would fix you with his friendly, steely gaze and smile.  Exceptional indeed for a computer scientist. 

Whether I came across him in a meeting, in the corridor, at a social gathering or somewhere like Waitrose, I would seek him out because I enjoyed talking to him so much.  He made me happy. He leaves not only a loving family but also a collection of workmates such as Jim and Ed to whom he was a special friend.   We in the department thought that we would soon have to face Ib’s retirement.  It is cruel that he was robbed of it like this.