+17. [Phil/ling application] Expletives
+
+18. Some references:
+ * [de Groote on the lambda-mu calculus in linguistics](http://www.loria.fr/%7Edegroote/papers/amsterdam01.pdf)
+ * [on donkey anaphora and continuations](http://dx.doi.org/10.3765/sp.1.1)
+ * [Wadler on symmetric sequent calculi](http://homepages.inf.ed.ac.uk/wadler/papers/dual-reloaded/dual-reloaded.pdf)