Linear expanded xanthines

Expansion of the xanthine ring system has been accomplished by linear formation of a benzo, pyrido or pyrazino ring between the pyrimidine and imidazole portions.

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Linear expandierte Xanthine (Kurze Mitteilung)

Zusammenfassung Durch Einbau eines Benzo-, Pyrido- oder Pyrazino-Ringes zwischen den Pyrimidin- und Imidazoleinheiten wurde die lineare Expansion des Xanthin-Ringsystems erreicht.

     

A property of the lattice of equational theories

It had been conjectured that any algebraic lattice having a compact one could be represented as the lattice of equational theories extending some theory. However, we show that each lattice having such a representation satisfies a nontrivial quasidistributivity condition. In particular,M ₃ has no such representation.To the memory of András HuhnPresented by Walter Taylor.     

Blei

Ohne Zusammenfassung