@InProceedings{alti:tlca01b, author = {Thorsten Altenkirch and Thierry Coquand}, title = {A Finitary Subsystem of the Polymorphic $\lambda$-calculus}, booktitle = {Typed Lambda Calculi and Applications, TLCA 2001}, pages = {22 - 28}, year = {2001}, number = {2044}, series = {Lecture Notes in Computer Science} }