Solution
= Solution
For $\kappa=|N|$, <saturation> means that every complete type over a subset of $N$ of cardinality less than $\kappa$ is realized in $N$. The model $N$ is a <universal model> when every model of $T$ of cardinality less than $\kappa$ elementarily embeds into $N$, and it is a <homogeneous model> when every partial elementary map between subsets of $N$ of cardinality less than $\kappa$ extends to an automorphism of $N$.