Computably Categorical Structures and Expansions by Constants

Effective model theory is the subject that analyzes the typical notions and results of model theory to determine their effective content and counterparts. The subject has been developed both in the former Soviet Union and in the west with various names (recursive model theory, constructive model theory, etc.) and divergent terminology. (We use “effective model theory” as the ∗Partially supported by a Mathematical Sciences Postdoctoral Research Fellowship and ARO through MSI, Cornell University, DALL03-91-C0027 †Partially supported by ISF, NQ6000 and NQ6300, and by ARO through MSI, Cornell University, DAAL03-91-C0027. ‡Partially supported by ARO through MSI, Cornell University, DAAL03-91-C0027. §Partially supported by NSF Grant DMS-9204308, DMS-9503503 and ARO through MSI, Cornell University, DAAL-03-C-0027.