Hi, The usual argument that not all tricategories can be strictified appeals to the existence of nontrivially braided monoidal categories. But this leaves open the possibility that a tricategory can be strictified completely aside from interchangors for endomorphisms of unit 1-morphisms, or something similar. Are results along these lines known? There are of course the results of Joyal and Kock that it is possible to put all the weak structure in the unitors. One could see this as mildly in support of the above proposal, where also the weak structure is closely related to unit morphisms. In the absence of hard facts, reasoned speculation would also be good to hear. Best wishes, Jamie [For admin and other information see: http://www.mta.ca/~cat-dist/ ]