M.J. Fischer, Et Al

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M.J. Fischer -- mid 60’s to mid 70’s M.J. Fischer -- mid 60’s to mid 70’s Division of Engineering and Applied Physics, Harvard, 1965 M.J. Fischer, et al., I was TA & Mike was 1st year student in Applied Math (206?), The First Decade: taught by Oettinger mid-60's to 70's Wow, was Mike smart! – and experienced:

M.J. Fischer -- mid 60’s to mid 70’s M.J. Fischer -- mid 60’s to mid 70’s Parsing Already (at Michigan) Already (at Michigan) An important theme for Mike: • equivalence (union/find) • paper on precedence parsing algorithms (1969 STOC) • thesis on Macro-grammars (1968, • MAD compiler & parsing Greibach) • LINGOL with Pratt

M.J. Fischer -- mid 60’s to mid 70’s M.J. Fischer -- mid 60’s to mid 70’s Parsing Harvard DEAP ’63 — ’68 …This is an area in which I have not worked, but I can relay the comment of Harrison at A romantic time -- Berkeley who told me shortly after reading pioneering a new discipline of theoretical Fischer’s paper on the subject that he was Computer Science: convinced that he and Fischer were the only Wang (& Cobham) two people who really understood on logic & computational complexity precedence grammars. -- students Aanderaa, Cook --letter from Meyer, Jan. 2 1975, Pat Fischer on Recursive Functions, to EECS Dept. Head supporting Automata, “real-time” automata Mike’s promotion to tenure. -- students Cole, Meyer, Ritchie, Rosenberg

1 M.J. Fischer -- mid 60’s to mid 70’s M.J. Fischer -- mid 60’s to mid 70’s Harvard DEAP ’63 — ’68 Harvard DEAP ’63 — ’68: people Stol Aanderaa G. Birkhoff Even & Greibach on automata & languages Ron Book Steve Cook -- students Mike Fischer, Book Shimon Even Pat Fischer Sheila Greibach Albert R. Meyer And nearby: Tony Oettinger Dennis Ritchie Rabin, Blum: time-bounded complexity Arny Rosenberg Hao Wang Alan Cobham Michael Rabin McNaughton/Papert, Krohn/Rhodes: Ed Moore Krohn-Rhodes Algebraic automata theory Manuel Blum McNaughton-Papert

M.J. Fischer -- mid 60’s to mid 70’s M.J. Fischer -- mid 60’s to mid 70’s Harvard DEAP ’63 — ’68 Harvard DEAP ’63 — ’68 …influenced Mike’s future work: -- string-matching • complexity of multiplication (w/ Wagner, JACM 1974; w/Paterson, SIAM-AMS Proc., 1974) -- improved “overlap” argument, following -- converting off-line to online losing Cook/Aanderaa, gave O(n log n) lower only a log n factor bound for online multiplication (w/Stockmeyer, STOC 1973), leading to (w/ Paterson/Meyer, SIAM-AMS -- fast parallel prefix circuits Proc. 1974) -- fast parallel prefix circuits (w/Ladner, JACM 1980)

M.J. Fischer -- mid 60’s to mid 70’s M.J. Fischer -- mid 60’s to mid 70’s Harvard DEAP ’63 — ’68 Mike & me: • translational argument, following P.Fischer/Ruby & Cook, for • Meyer to Carnegie Tech in ’67 nondeterministic time hierarchy • Fischer joins at CMU in ’68 (just (w/Meyer, Seiferas, JACM 1978) missing Floyd) • bounds on formula size • bounds on formula size • both to MIT Math/CS ’69-75 (w/ Meyer, Paterson, Vilfan)

2 M.J. Fischer -- mid 60’s to mid 70’s M.J. Fischer -- mid 60’s to mid 70’s Fischer-Meyer at MIT Fischer-Meyer at MIT Influential contributions: Less influential: • fast transitive closure • priority arguments in complexity • economy of description (w/Lynch, TransAMS, 1976) – “sets • λ-calculus schemata – CPS that don’t help” transform -- but connected Nancy & Mike (Only the last ever got refereed – • Ω(n log n) bounds on formula size 20 years later – but 100’s of (w/Paterson, SICOMP, 1982) citations) Copyright © Albert R. Meyer , 2003. All rights reserved. Fischer Fest, July 13, 2003 13. Copyright © Albert R. Meyer , 2003. All rights reserved. Fischer Fest, July 13, 2003 14.

M.J. Fischer -- mid 60’s to mid 70’s M.J. Fischer -- mid 60’s to mid 70’s Fischer-Meyer at MIT Fischer-Meyer at MIT Less influential: •Think-a-dot February 6, 1974 • failed mutual exclusion (w/Rivest, February 6, 1974 Pratt) MIT 6.045: Intro to Theory of Computation A. Meyer notes by M. Fischer -- but insightful, fixed later 1. THINK-A-DOT The mini-theory of the Think-a-Dot game which we develop in this section will serve as a paradigm of the kinds of questions we will investigate and the style of mathematics we will use in our studies of abstract machines.

M.J. Fischer -- mid 60’s to mid 70’s M.J. Fischer -- mid 60’s to mid 70’s Fischer-Meyer at MIT Fischer-Meyer at MIT •Think-a-dot – original implementation Lasting important contributions: • exponential complexity of decidable theories (w/ lots of students & Rabin) • Dynamic Logic (w/ Pratt, later Ladner at UW) • and of course …

3 M.J. Fischer -- mid 60’s to mid 70’s M.J. Fischer -- mid 60’s to mid 70’s Fischer-Meyer: PhD. students Open Problem Peter Bloniarz Jean Ferrante The complexity of multiplication Mike Hammer D.S. Johnson was a significant focus of Nancy Lynch Ed McCreight Mike’s work. Robbie Moll Nick Pippenger Can integer multiplication be Charles Rackoff Joel Seiferas computed in linear-time? Larry Stockmeyer Bostjan Vilfan Mitch Wand Frances Yao

M.J. Fischer -- mid 60’s to mid 70’s M.J. Fischer -- mid 60’s to mid 70’s Final Perspective Final Perspective Theoretical Computer Science was a new field without most We worked as a team -- with Paterson and our of today’s distinct subdisciplines. With a small community of students -- for fun and romance. colleagues and now-prominent students, Mike made seminal We thought our ideas would be valuable, but had contributions in this period to that a theoretician could be an * automata and formal language theory no clue that a theoretician could be an * graph algorithms entrepreneur. * programming language theory We captivated students with our enthusiasm and * computational complexity engaging problems . * logic of programs Some of what we did dead-ended – rightly so – but as well as working on • compilers, • graphics, • parsing, much remains the influential basis for current and • process synchronization research.

M.J. Fischer -- mid 60’s to mid 70’s M.J. Fischer -- mid 60’s to mid 70’s Final Perspective Drumlin Farm, Concord MA, Fall 1970

And, by the way, we did it while raising infants, maintaining large gardens, and (Mike & Alice) Naomi Teddy learning to figure skate. (age ≈ 10 mos.)

Albert Mike

4 M.J. Fischer -- mid 60’s to mid 70’s Final Perspective Is this perspective helpful in the context of today’s richly developed field of computation theory? I leave that for you to consider.