Frank Pfenning Invited talk: Tri-Directional Type Checking. 2002 70 Electr. Notes Theor. Comput. Sci. 1 http://www1.elsevier.com/gej-ng/31/29/23/125/51/show/Products/notes/index.htt#012 db/journals/entcs/entcs70.html#Pfenning02a