On Limitations of the Ehrenfeucht-Fraı̈ssé-method in Descriptive Complexity
نویسندگان
چکیده
Ehrenfeucht-Fraı̈ssé games and their generalizations have been quite successful in finite model theory and yield various inexpressibility results. However, for key problems such as P 6= NP or NP 6= co-NP no progress has been achieved using the games. We show that for these problems it is already hard to get the board for the corresponding Ehrenfeucht-Fraı̈ssé game. We obtain similar results for the so-called Ajtai-Fagin games and for a variant where the structures are obtained randomly.
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