Equivalence Relations on Classes of Computable Structures

@inproceedings{Fokina2009EquivalenceRO,
  title={Equivalence Relations on Classes of Computable Structures},
  author={Ekaterina B. Fokina and Sy-David Friedman},
  booktitle={CiE},
  year={2009}
}
If $\mathcal{L}$ is a finite relational language then all computable $\mathcal{L}$-structures can be effectively enumerated in a sequence in such a way that for every computable $\mathcal{L}$-structure $\mathcal{B}$ an index n of its isomorphic copy can be found effectively and uniformly. Having such a universal computable numbering, we can identify computable structures with their indices in this numbering. If K is a class of $\mathcal{L}$-structures closed under isomorphism we denote by K c… 
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