Tech Reports


On Pointed Enrichments and Illegal Compositions

Mark W. Johnson


This note gives a brief and relatively basic description of "adding an illegal point" to deal with forbidden compositions. The main result is Theorem 4.2, although Lemma 5.2 seems to have very broad applications. The point of the theorem is that 2-categories are not necessary to study reasonable examples of "precategories" with standard categorical techniques, despite this being the most common approach in the literature.

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