Constrained classes closed under unions and ne.c. structures
نویسنده
چکیده
We discuss those classes K of relational structures closed under unions that are de ned by excluding certain nite structures. We characterize such classes and show they contain an in nite family of pair-wise non-embeddable members. We investigate structures in K satisfying extension conditions and construct universal structures in K satisfying only nitely many of the extension conditions.
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ورودعنوان ژورنال:
- Ars Comb.
دوره 59 شماره
صفحات -
تاریخ انتشار 2001