Dear All, I have been trying to compare the simplicially enriched category/Segal-category approach to weak categories and the dg-category/$A_\infty$-category approach coming from derived categories etc. It is clear that there is a cobar construction leading from a dg-cocategory to a dg-category and results on twisting cochains also go across with no difficulty. I am therefore surprised that I cannot find an explicit reference for this in the literature (probably I have not loked in the right place as it is in an `overlap' area!). Can anyone help with some good references? Also has anyone given a good interpretation of the twisting cochains and the twisted tensor of modules in this setting. I know of the usual interpretations. Perhaps someone who knows the string theoretic links may have an idea. Thanks, Tim Porter