Relation algebras: Concept of points and representability

AbstractIn the axiomatization of relation algebras by Chin and Tarski certain elements are called right ideals. Aiming at applications in the relational theory of graphs and programs, we call such ideals ‘points’ and investigate an additional point axiom. First we prove a point insertion theorem. Then a representation theorem for such relation algebras is deduced by inherently relational methods, simplifying the proof of a similar result from Jónsson, Maddux and Tarski. Some historical remarks are inserted and an extended bibliography is added

The iBeetle large-scale RNAi screen reveals gene functions for insect development and physiology

Genetic screens are powerful tools to identify the genes required for a given biological process. However, for technical reasons, comprehensive screens have been restricted to very few model organisms. Therefore, although deep sequencing is revealing the genes of ever more insect species, the functional studies predominantly focus on candidate genes previously identified in Drosophila, which is biasing research towards conserved gene functions. RNAi screens in other organisms promise to reduce this bias. Here we present the results of the iBeetle screen, a large-scale, unbiased RNAi screen in the red flour beetle, Tribolium castaneum, which identifies gene functions in embryonic and postembryonic development, physiology and cell biology. The utility of Tribolium as a screening platform is demonstrated by the identification of genes involved in insect epithelial adhesion. This work transcends the restrictions of the candidate gene approach and opens fields of research not accessible in Drosophila