文章基本信息

标题：Co-tabulations, Bicolimits and Van-Kampen Squares in Collagories
本地全文：下载
作者：Wolfram Kahl
期刊名称：Electronic Communications of the EASST
电子版ISSN：1863-2122
出版年度：2010
卷号：29
语种：English
出版社：European Association of Software Science and Technology (EASST)
摘要：We previously defined collagories essentially as “distributive allegories without zero morphisms”. Collagories are sufficient for accommodating the relation-algebraic approach to graph transformation, and closely correspond to the adhesive categories important for the categorical DPO approach to graph transformation. Heindel and Sobocinski have recently characterised the Van-Kampen colimits used in adhesive categories as bicolimits in span categories. In this paper, we study both bicolimits and lax colimits in collagories. We show that the relation-algebraic co-tabulation concept is equivalent to lax colimits of difunctional morphisms and to bipushouts, but much more concise and accessible. From this, we also obtain an interesting characterisation of Van-Kampen squares in collagories.