Alternative Resources

Further open problems published elsewhere can be found in many places.

• Many related interesting problems are presented in the RTA List of Open Problems.

  http://www.lsv.ens-cachan.fr/rtaloop/ .

  In particular, look at problems 1,4,5,15,17,19,45,50,52-55,78,88,94,96,97.

• Some open problems collected by Henk Barendregt can be found in [Barendregt, 1975].
• A list of open problems collected at a 1993 Utrecht meeting of the Gentzen Working Group is available from http://www.mimuw.edu.pl/tlca/Gentzen93/ .
• A lot of open problems can be found in some papers of Chantal Berline , in particular [Berline, 2000, Berline, 2006].