[HN Gopher] Alonzo Church: Architect of computer intelligence
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Alonzo Church: Architect of computer intelligence
Author : drcwpl
Score : 191 points
Date : 2024-11-04 14:51 UTC (8 hours ago)
(HTM) web link (onepercentrule.substack.com)
(TXT) w3m dump (onepercentrule.substack.com)
| cubefox wrote:
| Especially his philosophy of logic and sense/reference (a
| continuation of the work of Frege and Russell) is mostly
| forgotten. He published many papers on this topic, yet they
| aren't discussed e.g. in Wikipedia. At least the SEP entry is
| better:
|
| https://plato.stanford.edu/entries/church/
|
| Though I heard that it also neglects some major parts of his
| work. I assume it was too philosophical for mathematicians and
| too technical for philosophers.
| gpderetta wrote:
| "Church's lambda calculus and the Turing machine are equally
| powerful but differ in the fact that Turing machines use mutable
| state. To this day, there is a rift between functional and
| imperative programming languages, because of the separation of
| Church and state."
|
| [I have known the above quote forever, but I can't find an
| original source]
|
| edit: might be from Guy Steele: "And some people prefer not to
| commingle the functional, lambda-calculus part of a language with
| the parts that do side effects. It seems they believe in the
| separation of Church and state"
| drcwpl wrote:
| That is such a great quote - classic programming humor, but no
| idea of the original
| rbonvall wrote:
| Just like Niklaus Wirth's quote about how people used to call
| him, or the joke about there being 10 kinds of people.
|
| Those are the ones that make me wish people knew just enough
| Computer Science to get them :)
| tialaramex wrote:
| "There's two hard problems in computer science: we only
| have one joke and it's not funny" which I've seen credited
| to Phillip Scott Bowden
|
| Which is a reference to the "two hard problems" jokes, the
| most used is "There are two hard problems in Computer
| Science: Cache invalidation, naming things, and off-by-one
| errors"
|
| But there is also "Two hard problems in distributed
| systems: Exactly-once delivery, guaranteed order of
| messages, and exactly-once delivery".
| f1shy wrote:
| I think it is from Peter Norvig, look the sister comment.
| tjr wrote:
| Guy's quote there came from a mailing list at MIT that was
| formed out of the 2001 Lightweight Languages Workshop. Archive
| of the original post here:
|
| https://people.csail.mit.edu/gregs/ll1-discuss-archive-html/...
| gpderetta wrote:
| Perfect! Thanks for the source.
| sourcepluck wrote:
| A historical tidbit which I loved in Paradigms of Artificial
| Intelligence Programming (available in PDF and EPUB here -
| https://github.com/norvig/paip-lisp):
|
| > The name lambda comes from the mathematician Alonzo Church's
| notation for functions (Church 1941). Lisp usually prefers
| expressive names over terse Greek letters, but lambda is an
| exception. A better name would be make-function. Lambda derives
| from the notation in Russell and Whitehead's Principia
| Mathematica, which used a caret over bound variables: x(x + x).
| Church wanted a one-dimensional string, so he moved the caret in
| front: ^x(x + x). The caret looked funny with nothing below it,
| so Church switched to the closest thing, an uppercase lambda,
| Lx(x + x) . The L was easily confused with other symbols, so
| eventually the lowercase lambda was substituted: lx(x + x). John
| McCarthy was a student of Church's at Princeton, so when McCarthy
| invented Lisp in 1958, he adopted the lambda notation. There were
| no Greek letters on the keypunches of that era, so McCarthy used
| (lambda (x) (+ x x)), and it has survived to this day.
|
| So, yes, on the topic of this post - Church pops up in loads of
| Lisp retrospectives. Maybe he's "forgotten" by people with very
| little engagement in the history of computing.
| drcwpl wrote:
| Great tidbit, (thanks for the Paradigms share) - in the
| footnote I mention about CS folks awareness.
| agumonkey wrote:
| But wait, who ever first coined the term 'lambda calculus' ?
| was it before or after McCarthy started lisp ?
| seanhunter wrote:
| Well before. The original paper[1] introducing the lambda
| calculus was in the 1930s, but it wasn't called "lambda
| calculus" until a bit later.
|
| [1] https://raw.githubusercontent.com/emintham/Papers/master/
| Chu...
| agumonkey wrote:
| Yeah indeed no trace of the term 'lambda'.
|
| But this https://www.classes.cs.uchicago.edu/archive/2007/s
| pring/3200... mentions "THE CALCULI OF LAMBDA-CONVERSION"
| linked here https://compcalc.github.io/public/church/church
| _calculi_1941...
| f1shy wrote:
| BTW the PAIP book, independent of AI topics (where it did not
| age so good) is an excellent book overall, covering many
| programming topics, and opening some paradigms, that for people
| who had little exposure to FP might be unknown.
| CodeArtisan wrote:
| >There were no Greek letters on the keypunches of that era, so
| McCarthy used (lambda (x) (+ x x)), and it has survived to this
| day.
|
| I have a memory of a paper by McCarthy himself where he tells
| that the first implemented Lisp had a notation close to
| FORTRAN. S-expressions were only intended for the theory.
| trenchgun wrote:
| This does not seem correct. There was a vision of using
| M-expressions, (Metalanguage) but it never happened.
|
| >In computer programming, M-expressions (or meta-expressions)
| were an early proposed syntax for the Lisp programming
| language, inspired by contemporary languages such as Fortran
| and ALGOL. The notation was never implemented into the
| language and, as such, it was never finalized
| https://en.wikipedia.org/wiki/M-expression
| llm_trw wrote:
| https://en.wikipedia.org/wiki/M-expression
|
| It was never implemented.
|
| It was M-expressions which users were to interact with, and
| S-expressions were what the machine would use.
| Chinjut wrote:
| "Lisp usually prefers expressive names". In addition to the
| exception of "lambda", there are also "car" and "cdr", which,
| while not Greek, are hardly transparent.
| lispm wrote:
| "usually" probably means at the time of writing this book.
| lambda, car and cdr are from the 50s/60s when short names
| were preferred for various reasons (small memory, input on
| cards, output on paper, small screens, ...).
| Chinjut wrote:
| It's not clear that this oft-repeated story of the origin of
| Alonzo Church's lambda notation is true. See
| https://en.wikipedia.org/wiki/Lambda_calculus#Origin_of_the_...
| for other instances where Alonzo Church has suggested it was
| more of an arbitrary choice of Greek letter.
| tromp wrote:
| The Alonzo programming language named after him [1] has mostly
| been forgotten.
|
| [1] https://dl.acm.org/doi/pdf/10.1145/68127.68139
| dang wrote:
| [stub for offtopicness]
|
| Side remark: "Please don't take the bait" is a good analogue to
| "please don't feed the trolls".
|
| We've taken the bait out of the title now, but when a thread has
| already filled up with comments reacting to it, rather than
| anything interesting, that's bad for HN threads.
| seanhunter wrote:
| "Forgotten" in the sense that everyone who knows anything about
| CS knows who he is because of the Church-Turing hypothesis,
| Church numerals, lambda calculus etc, and anyone who reads "On
| Computable Numbers" (only the most famous paper in all of
| computer science) knows that Turing actually quotes and credits
| Church and his work in that paper.
|
| Here's a link to "On Computable Numbers" for easy reference for
| anyone who wants to read it/read it again. It's a cracker
| https://www.cs.virginia.edu/~robins/Turing_Paper_1936.pdf
| abstractbeliefs wrote:
| Forgotten not in the sense of lost knowledge, but more that
| the individual is not known proportionally to the importance
| of his work, or perhaps consistently when compared to his
| peers.
|
| While specialists in his field know his work and his name
| (but not even everyone in software does), the public do not.
|
| While your parents and friends see the dramatised exploits of
| Turing in films like The Imitation Game, or his face on the
| currency, the same is not said for Church.
|
| Every field has it's public heroes, usually related to the
| stature of their work - Fleming and Jenner, Marconi, Ford,
| Bell. Turing.
|
| Anyone will at least recognise these names, but not so for
| Church.
| gilleain wrote:
| Ok, and if I asked a random member of the public for the
| name of a mathematician (excepting Turing, for clarity)
| what name do you think they would come up with? Pythagoras?
| Euler? Erdos?
|
| I think the reality is that only a very small number of
| scientists, mathematicians, and similar are household
| names.
| ggm wrote:
| People's conception of Turing is massively skewed by the
| ending. His persona is now defined by his sexuality and
| treatment more than his contributions to maths and
| computer science. Andrew Hodges book is great. I had the
| fortune to go to his author tour the year it came out, he
| was doing the compsci departments of the UK and it was a
| really nice seminar.
|
| Benedic Cumbersome was a good actor, but it's important
| to remember Michelangelo actually didn't look like Kirk
| Douglas.
| gpderetta wrote:
| Also his contribution to the war might be one of the
| biggest reason he is well known.
| geodel wrote:
| I like that you called Benedict 'Cumbersome'. He is
| indeed cumbersome in so many roles.
| ggm wrote:
| I read a review in the Guardian [1] which used a series
| of malapropisms for his name, and riffed on the concept.
|
| [1] https://www.theguardian.com/tv-and-
| radio/article/2024/may/29...
| seanhunter wrote:
| Right - For every Newton, who (rightly) gets credit for
| his immense contributions, there are people like Euler,
| who are relatively unknown outside the field in spite of
| significant contributions[1].
|
| [1] Massive in the case of Euler obviously.
| drcwpl wrote:
| Agreed - what I tried to highlight through a series about
| people that have contributed significantly, but are not
| so well known outside of the fields they impacted, there
| is always cooperation to a large extent and others
| involved - rarely a lone individual as the Turing movie
| and much of the press in the UK likes to portray. And
| many people, who should be known, get lost in the
| complexity of history. It's worth bringing the attention
| of this to a wider audience - people are genuinely
| inquisitive. Plus as another example, on an intro course
| to AI 45 out of 52 bachelor students had never heard of
| Church!
| mitthrowaway2 wrote:
| Isn't that just because they haven't made a blockbuster
| feature film about him yet?
| PittleyDunkin wrote:
| Oh so maybe 0.01% of the population will even recognize his
| name
| conductr wrote:
| As evidence, I've been programming for 25 years now but
| never actually studied CS. Yet throughout that duration I
| feel like I see/read Turing's name every week somewhere.
| I've never heard of Church until now.
| drcwpl wrote:
| Great point - thanks for that.
| kayo_20211030 wrote:
| Dammit! Did I forget to forget him? Seems pretty memorable to
| me, and I'm just a regular dev.
| drcwpl wrote:
| The main theme of the essay is his work which helped the
| foundation of AI, In their book Artificial Intelligence A
| Modern Approach (Third Edition), Russell and Norvig give
| limited (cursory) commentary about A. Church, but Turing
| gets the foundational credites, I think that is an
| oversight - and this book has sold in the hundreds of
| thousands and is used on AI courses extensively!
| cubefox wrote:
| It's ironic that you reference a paper by Turing here but not
| one by Church himself.
| drcwpl wrote:
| I also add the Turing one at the end of the post also
| because of the discussions at the beginning - especially
| "Church had certainly obtained the result before Turing"
| nesarkvechnep wrote:
| Forgotten by whom? Certainly not by me.
| drcwpl wrote:
| The point is about a wider audience - I believe it is good to
| highlight people that have contributed significantly, yet
| overlooked by society at large - agreed about the CS sector,
| but then again on my intro to AI course less than 7% of
| bachelor students have heard of him in this context!
| dang wrote:
| If you want to read something incredible about Church, read
| Rota's reminiscence. It's the first section of
| https://www34.homepage.villanova.edu/robert.jantzen/princeto....
|
| Related:
|
| _Alonzo Church, 92, Theorist of the Limits of Mathematics(1995)_
| - https://news.ycombinator.com/item?id=12240815 - Aug 2016 (1
| comment)
|
| _Gian-Carlo Rota on Alonzo Church (2008)_ -
| https://news.ycombinator.com/item?id=9073466 - Feb 2015 (2
| comments)
| drcwpl wrote:
| That is brilliant, thank you - I added the Rota one as an
| addendum under the further reading at the end.
| devindotcom wrote:
| This was entertaining, thanks for the link.
| svat wrote:
| Rota's reminiscence (not just the part about Church but the
| entire webpage, namely "Fine Hall in its golden age:
| Remembrances of Princeton in the early fifties") is, as the
| asterisked footnote alludes to, a chapter of his book
| _Indiscrete Thoughts_. The whole book is great reading.
| tomgp wrote:
| Not really the point BUT... I really wish people would refrain
| from using AI illustrations on blog posts. There are actual
| pictures of Church in the public domain, this illustration
| doesn't particularly look like him and is already appearing in
| image search results for the man thanks to the blog post's
| popularity. If the illustration has so little value that you
| can't be bothered to spend more than 5 minutes generating it then
| perhaps just leave it out?
|
| [edit] ... and if you really must use "AI" generated imagery then
| at least caption it as such.
| Robotenomics wrote:
| Thank you. Noted and sorry - I was loathe to take an online
| photo ... this one was actually 7th effort as I did not want
| the 'fake' likeness, I felt it captured a resemblance... I
| managed a good one of JvN but you are right to address this. I
| think in future I will use a symbol rather than a 'character
| (un) likeness '
| priprimer wrote:
| the real challenge of understanding lamba calculus is realizing
| its simplicity
|
| it is a sacred idea by the fact that executing it does not really
| help understand the fact that it is equivalent to any and all
| computation
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