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Mutual definability does not imply definitional equivalence, a simple example

✍ Scribed by Hajnal Andréka; Judit X. Madarász; István Németi


Publisher
John Wiley and Sons
Year
2005
Tongue
English
Weight
129 KB
Volume
51
Category
Article
ISSN
0044-3050

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✦ Synopsis


We give two theories, Th1 and Th2, which are explicitly definable over each other (i. e. the relation symbols of one theory are explicitly definable in the other, and vice versa), but are not definitionally equivalent. The languages of the two theories are disjoint.