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Obviously a logic, such as classical propositional logic (or the modal logic S5), is not a structure, but a class of equivalent or identical structures, since it can be presented in many different ways (choice of primitive connectives, consequence relation vs tautologies, etc.) .
The problem is to find a good definition of equivalence or identity between logics which is reasonable and applies to a wide range of particular cases.
The standard definition, "to have a common expansion by definition up to isomorphism", does not apply straightforwardly, as pointed by Béziau et al. (2001). Proposals such that one of Pollard (1998) or Pelletier and Urquhart (2003) apply only to some special situations.
So this fundamental problem is still open and we hope that someone will present a satisfactory solution in Montreux.

References
*J.-Y. Béziau, R.P. de Freitas, J.P. Viana. What is Classical Propositional Logic? (A Study in Universal Logic), Logica Studies 7, 2001.
*F.J. Pelletier & A. Urquhart. Synonymous Logics , Journal of Philosophical Logic, 32, 2003, pp. 259-285.
*Stephen Pollard. Homeomorphism and the Equivalence of Logical Systems , Notre Dame Journal of Formal Logic, 39, 1998, pp.422-435.


			How to take part in the contest? All participants of the school and the congress are welcome to take part in the contest. Short papers (up to 10 pages) can be submitted before October 30, 2004. The best ones will be selected for presentation at a special session during the congress and a jury will then decide which, if any, is the winner. The members of the Jury are Gerhard Jaeger, Vladimir Vasyukov and Hermann Hauesler. The prize will be offered by
	Contest: How to define identity between logics? Obviously a logic, such as classical propositional logic (or the modal logic S5), is not a structure, but a class of equivalent or identical structures, since it can be presented in many different ways (choice of primitive connectives, consequence relation vs tautologies, etc.) . The problem is to find a good definition of equivalence or identity between logics which is reasonable and applies to a wide range of particular cases. The standard definition, "to have a common expansion by definition up to isomorphism", does not apply straightforwardly, as pointed by Béziau et al. (2001). Proposals such that one of Pollard (1998) or Pelletier and Urquhart (2003) apply only to some special situations. So this fundamental problem is still open and we hope that someone will present a satisfactory solution in Montreux. References J.-Y. Béziau, R.P. de Freitas, J.P. Viana. What is Classical Propositional Logic? (A Study in Universal Logic), Logica Studies 7, 2001. F.J. Pelletier & A. Urquhart. Synonymous Logics , Journal of Philosophical Logic, 32, 2003, pp. 259-285. *Stephen Pollard. Homeomorphism and the Equivalence of Logical Systems , Notre Dame Journal of Formal Logic, 39, 1998, pp.422-435.