4 papers · 1 filter
A Note on Computable Embeddings for Ordinals and Their Reverses
Nikolay Bazhenov, Stefan Vatev
We continue the study of computable embeddings for pairs of structures, i.e. for classes containing precisely two non-isomorphic structures. Surprisingly, even for some pairs of si…
Coding in graphs and linear orderings
Julia Knight, Alexandra Soskova, Stefan Vatev
There is a Turing computable embedding of directed graphs in undirected graphs. Moreover, there is a fixed tuple of formulas that give a uniform interpretation; i.e., for a…
Cohesive Powers of Linear Orders
Rumen Dimitrov, Valentina Harizanov, Andrey Morozov +3
Cohesive powers of computable structures can be viewed as effective ultraproducts over effectively indecomposable sets called cohesive sets. We investigate the isomorphism types of…
Strong Jump Inversion
W. Calvert, A. Frolov, V. Harizanov +4
We say that a structure admits \emph{strong jump inversion} provided that for every oracle , if computes for some $\mathcal{C}\cong\mathcal{…