Aho on inventing indexed grammars and the nested stack automaton for his Ph.D. thesis. 

Alfred Vaino Aho, winner of the Association for Computing Machinery's A.M. Turing Award, explains how in invented indexed grammars and the nested stack automaton to recognize them while working on his Ph.D. thesis at Princeton under the direction of John Hopcroft. This clip is taken from an interview conducted with Aho by Hansen Hsu for the ACM and Computer History Museum on June 13, 2022. Video of the full interview is available as part of Aho’s ACM profile at amturing.acm.o....