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, и C. Roth. Proceedings of the 15th International Conference on Conceptual Structures (ICCS 2007), том 4604 из Lecture Notes in Artificial Intelligence, стр. 241-254. Berlin, Heidelberg, Springer-Verlag, (июля 2007)