Editing Kenneth Appel (section)

===Group theory===
Kenneth Appel's other publications include an article with P.E. Schupp titled ''Artin Groups and Infinite Coxeter Groups''. In this article Appel and [[Schupp]] introduced four theorems that are true about [[Coxeter groups]] and then proved them to be true for [[Artin group]]s. The proofs of these four theorems used the "results and methods of small cancellation theory."<ref name="Artin">{{cite journal |last1=Appel |first1=Kenneth I. |first2=P. E. |last2=Schupp |title=Artin Groups and Infinite Coxeter Groups |journal=[[Inventiones Mathematicae]] |volume=72 |issue=2 |year=1983 |pages=201–220 |doi=10.1007/BF01389320 |bibcode=1983InMat..72..201A |s2cid=15886682 }}</ref>