A new spectrum of computable models

In the paper we prove that there exist models $\mathfrak A$ and $\mathfrak B$ of an Ehrenfeucht theory such that $\mathfrak A$ is elementary embeddable into $\mathfrak B$, $\mathfrak B$ is elementary embeddable into $\mathfrak A$, model $\mathfrak A$ has a computable presentation, model $\mathfrak B$ has no computable presentation. This theorem together with the work [6] is the key result for the theorem describing co