To congratulate Bengt for his contributions to computer science, and to commemorate the tradition in Gothenburg that he was instrumental in founding, we are organizing this symposium.
Second, two differences: (1) For a natural scientist, reality precedes the model, and in informatics the model comes first. (2) In informatics, probably more than in natural science, we have to create a tower of models at increasing levels of abstraction; these models can (and should) be rigorous entities, and we can (and should) rigorously verify that each abstracts correctly from the those below it.
The von Neumann machine is a low-level model that has been abstracted successfully, over half a century, to higher levels. It is a platform for higher-order sequential computing, as evidenced by the multitude of high-level languages that abstract from it.
The von Neumann machine is no good for ubiquitous computing, where we are concerned with interaction in populations of informatic entities, which also reconfigure their structural (spatial) relationship. These, and their space, can be physical or virtual. What is a platform model for ways to think abstractly about ubiquitous computing? I put forward bigraphs as a Ubiquitous Abstract Machine.
Robin Milner is professor emeritus at the University of Cambridge Computer Laboratory. He received the Turing award in 1991 for his work on "1) LCF, probably the first theoretically based yet practical tool for machine assisted proof construction; 2) ML, the first language to include polymorphic type inference together with a type-safe exception-handling mechanism; 3) CCS, a general theory of concurrency". Prior to that Robin Milner had been awarded an honorary doctorate at Chalmers for his role as a source of inspiration for the development of computer science at Chalmers.
Per Martin-Löf is professor of Mathematical Logic at the Department of Mathematics at University of Stockholm. He is the creator of Intuitionistic Type Theory, a foundational language for constructive mathematics which is simultaneously a functional programming language with dependent types. This language has been very influential both in the area of programming languages and in the area of interactive proof assistants. Per Martin-Löf has collaborated with Bengt Nordström and others in Gothenburg on the application of this theory to computer science.
In this talk I'll show some examples of how Haskell works out very well, but also where it falls short of doing the best job. The ugly will also make some appearances.
Lennart Augustsson works at Standard Chartered Bank, London, England. He was previously a lecturer in Computer Science at Chalmers, and one of the initial members of the Programming Methodology Group. Lennart Augustsson did ground breaking work on compilers for lazy functional programming languages. During recent years he has held numerous industrial appointments, where he has applied functional programming in areas ranging from banking to hardware description.
Thierry Coquand is professor of Programming Logic at the Department of Computer Science and Engineering, University of Gothenburg. He received the Kurt Gödel Centenary Research Prize Fellowship in 2008 "for his pioneering research into the foundations of mathematics". Thierry Coquand works at the boundary between mathematical logic and theoretical computer science, and has investigated the links between mathematical proof and computer programs. He is one of Bengt Nordström's colleagues in the Programming Logic group.
Robin Cooper is professor of Computational Linguistics at the University of Gothenburg and is known for his pioneering work on the semantics of natural language, in particular on quantifiers. Soon after coming to Gothenburg in 1995, he and Bengt Nordström started a cooperation, which led to the founding of the Language Technology group at the Department of Computer Science and eventually to the multidisciplinary Centre of Language Technology, one of the eight focus areas of research of the University of Gothenburg.