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Johannes Heidema (by proxy) and Dr Willem Labuschagne, Department of Computer Science (in the flesh)


In search of the lost consequence relation.


Archway 2

Brief Biography:

Professor Heidema of the University of South Africa has been a long-standing research partner of Willem's and visited the Department of Computer Science as William Evans Fellow in 2000.


Logic is basically about the following question: if these were the facts, then what consequences would follow?

Classical logic uses the consequence relation invented by Alfred Tarski, which provides a semantic basis for familiar notions of proof. Modern nonmonotonic logic uses a "defeasible" consequence relation obtained by generalising the classical consequence relation in a particular way. But there are TWO obvious ways to generalise the classical consequence relation, not just one. So why has the second generalisation never been considered?

This is an account of the trials and tribulations of two intrepid adventurers in the land of nonmonotonic logic, searching for the lost consequence relation. They pick their way through the jungle, bravely stumbling over tangled vines and hurling themselves upon the four-footed furry creatures they meet. Finally they realise that the beast they seek has feathers instead of fur and wings instead of feet.

Last modified: Wednesday, 25-May-2005 09:30:33 NZST

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