G. Bergman. (2016)cite arxiv:1602.00034Comment: Comments: 50 pages. Main change from version 2: Lemma 26 strengthened to include contractibility statement which in previous version was noted as "likely" in paragraph following that result. Several small typoes also corrected.
S. Kuznetsov, S. Obiedkov, und C. Roth. Proceedings of the 15th International Conference on Conceptual Structures (ICCS 2007), Volume 4604 von Lecture Notes in Artificial Intelligence, Seite 241-254. Berlin, Heidelberg, Springer-Verlag, (Juli 2007)