@article {IOPORT.06005014, author = {Ivanov, Aleksander}, title = {Degrees of isomorphism types and countably categorical groups.}, year = {2012}, journal = {Archive for Mathematical Logic}, volume = {51}, number = {1-2}, issn = {0933-5846}, pages = {93-98}, publisher = {Springer-Verlag, Berlin}, doi = {10.1007/s00153-011-0255-6}, abstract = {A countable structure with the universe $\omega$ is said to be of (Turing) degree $\bold{d}$ iff its atomic diagram has degree $\bold{d}$. By the spectrum $\mathrm{Spec}(\mathcal{M})$ of a structure $\mathcal{M}$ we mean the set of degrees of structures isomorphic to $\mathcal{M}$. If $\mathrm{Spec}(\mathcal{M})$ has a least element $\bold{d}$ then $\mathcal{M}$ is said to have degree $\bold{d}$; otherwise, we say that $\mathcal{M}$ has no degree. The main result of the paper under review is following: Theorem. (i) For every Turing degree $\bold{d}$ there is a 2-step nilpotent group $\mathfrak{G}$ of exponent four so that $\mathfrak{G}$ has a countably categorical theory submodel complete (i.e., with quantifier elimination) theory and has degree $\bold{d}$. (ii) There is a 2-step nilpotent group $\mathfrak{G}$ of exponent four so that $\mathfrak{G}$ has a countably categorical theory submodel complete theory and has no degree. The author uses the Fra\"{\i}ss\'e method for constructing both series of examples.}, reviewer = {Vadim Puzarenko (Novosibirsk)}, identifier = {06005014}, }