The subdirect decomposition theorem for classes of structures closed under direct limits

investigating the feasibility of a proposed model for geometric design of deployable arch structures

deployable scissor type structures are composed of the so-called scissor-like elements (sles), which are connected to each other at an intermediate point through a pivotal connection and allow them to be folded into a compact bundle for storage or transport. several sles are connected to each other in order to form units with regular polygonal plan views. the sides and radii of the polygons are...

On Arithmetical Classes Not Closed under Direct Union1

Constrained classes closed under unions and ne.c. structures

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.

Decomposition Theorem for Abstract Elementary Classes

elementary classes (AEC) were introduced by Shelah to generate a common framework to treat those classes of models that, in spite of being non-elementary, behave similarly to elementary classes. Part of the motivation was the study of classes of models for theories in infinitary languages. As stated in the introduction, Rami Grossberg and Olivier Lessmann presented an axiomatic framework which ...

nano-rods zno as an efficient catalyst for the synthesis of chromene phosphonates, direct amidation and formylation of amines

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