We give a detailed comparison between the notion of a weak Hopf algebra (also called a quantum groupoid by Nikshych and Vainerman), and that of a -bialgebra due to Takeuchi (and also called a bialgebroid or quantum (semi)groupoid by Lu and Xu). A weak bialgebra is the same thing as a -bialgebra in which R is separable. We extend the comparison to cover module and comodule theory, duality, and the question when a bialgebroid should be called a Hopf algebroid.
@article{bwmeta1.element.bwnjournal-article-doi-10_4064-bc61-0-12, author = {P. Schauenburg}, title = {Weak Hopf algebras and quantum groupoids}, journal = {Banach Center Publications}, volume = {60}, year = {2003}, pages = {171-188}, zbl = {1064.16041}, language = {en}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-bc61-0-12} }
P. Schauenburg. Weak Hopf algebras and quantum groupoids. Banach Center Publications, Tome 60 (2003) pp. 171-188. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-bc61-0-12/