The HLF Portraits: Leslie Lamport

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The HLF Portraits: Leslie Lamport
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The Heidelberg Laureate Forum Foundation presents the HLF Portraits: Leslie Lamport; ACM A.M. Turing Award, 2013 Recipients of the the Abel Prize, the ACM A.M. Turing Award, the ACM Prize in Computing, the Fields Medal and the Nevanlinna Prize in discussion with Marc Pachter, Director Emeritus National Portrait Gallery, Smithsonian Institute, about their lives, their research, their careers and the circumstances that led to the awards. Video interviews produced for the Heidelberg Laureate Forum Foundation by the Berlin photographer Peter Badge. The opinions expressed in this video do not necessarily reflect the views of the Heidelberg Laureate Forum Foundation or any other person or associated institution involved in the making and distribution of the video. Background: The Heidelberg Laureate Forum Foundation (HLFF) annually organizes the Heidelberg Laureate Forum (HLF), which is a networking event for mathematicians and computer scientists from all over the world. The HLFF was established and is funded by the German foundation the Klaus Tschira Stiftung (KTS), which promotes natural sciences, mathematics and computer science. The HLF is strongly supported by the award-granting institutions, the Association for Computing Machinery (ACM: ACM A.M. Turing Award, ACM Prize in Computing), the International Mathematical Union (IMU: Fields Medal, Nevanlinna Prize), and the Norwegian Academy of Science and Letters (DNVA: Abel Prize). The Scientific Partners of the HLFF are the Heidelberg Institute for Theoretical Studies (HITS) and Heidelberg University.
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[Music] you Leslie but may call you that you're by your first name most of this is going to be a discussion about your career but it's the becoming that computer analysts that I'm interested in to start so can I place you in your childhood I'm gonna choose the year 10 years old just arbitrarily but you can pick another year but who are your parents were you living oh my parents are I guess there would be called Jewish immigrants but they came when there were children so spoke English with no accent my mother was a housewife but she had been a milliner before she got married and what may be relevant is my father although we worked in a dry cleaning establishment he had studied to be a doctor in the sense of having taken a pre-med course in college but since that was the depression he for economic reasons he was enabled to I presume if we there were economic reasons but that probably influenced me in the sense of he may have been responsible for my being interested in science or that may have been just innate I have no idea I think you would have more of a certain sense of that if he had pushed you in any way towards science and I'm getting a sense that that wasn't happening I'm not to my memory mm-hmm if they pushed me to anything it might have been slightly to wanting to me to be a doctor yes but that was just in the sense that at some point I decided I wanted a microscope because looked through a neighbor's microscope and they were supportive and let me buy one with money from Bar Mitzvah gifts and I think the reason was they had hopes that that would lead me into wanting to become a doctor but they never I thought but not it wasn't in the air this is what we want for you know are you an only child no I had an older brother and was he perhaps influential you know I'm without pushing too hard I'm just wondering about intellectual influences or whatever they may not have been strong or apparent what were what was he like he was probably my exact opposite he event he had artistic ability and became a commercial artist and did some you know really lovely stuff and I am totally capable of drawing anything yeah and on hit on the other hand I think he would have been terrible he probably was terrible in mathematics and and in foreign languages and I was good in those so when were you beginning to notice again a child lives his life doesn't necessarily judge it along the way but when are you beginning to find your aptitudes in school is there a a good program I mean you're in New York City where the teaching might have been very good but you can tell me about that too what is the environment outside the home that is shaping you or leading you to recognize what you're good at well I'm not sure that I recognized it but other people did I was clearly you know one of the best or the best student in in my classes and from early on trees grow yes yeah and in junior high school I went into a program of doing three years and two already yes and I learned later in life that my parents were approached by I think with the opportunity of enrolling me in a special course for at Columbia University who or gifted children and that would have been while I was still in elementary school really and my mother didn't want me to do it because she wanted me to have a more normal childhood right and so you didn't do it right oh I didn't even know about it right so this is the opposite of pushing you in one direction and yes she wanted a happy childhood for you and that wasn't going to be part of it in her but I presume again this is something this is time assuming what she's thinking and but that being said in junior high even before you've been marked or recognized as able certainly able abled particularly in science and mathematics or in general are you a good student in most subjects except drawing well I think I would be getting A's or what if the grades we're given then yeah yeah after school I don't remember and in all the subjects I well I remember I an uncle who taught history and I remember asking them well what's the point of history I hope you've got an answer I probably did I don't remember what it is but so it was clear that in in some sense my interests were not in the humanities but there are in the sciences right now I'm looking for he or she may not exist a particularly significant teacher maybe in junior high maybe by the time you're in high school and I know you go to Bronx Science so you're
already people are noticing that you're good at this and you're going to an excellent high school somebody is encouraging you
somebody is saying go to Bronx Science
what what is happening oh well first of
all at Bronx Science you know I was not I don't think you know an outstanding genius in the sense that there were there were two students who I'm not sure if they were better at math in math than I was but there was the math team and there were certainly much better than I really had that but math team is measuring not just intelligence but we're quickness this response though and I've never been that quick on my feet ah and my recollection is at Bronx Science and overall ranking I was something like in the 20s mm-hmm which is I mean pretty good at Bronx Science yes yes but a few several hundred people in the class but but nevertheless not a stars and I think again I'm still searching for that teacher even though you may not be a star or on the math team or the best on it who's who's noticing you because and you and maybe only you developing your own
intellectual curiosity I actually do not remember having mentors okay in school at any point and the I can remember in one of my memories is of a teacher who was clearly not fit to be my mentor and wasn't that it was in elementary algebra and we were studying factoring quadratic equations and I asked him how do you know that there's only one way to factor an algebraic equation now this I mean if a child asks that it was just such an an a doorway to teaching them about prime numbers and you know unique factorization and stuff but holy did was say well that's just the way it is oh the worst kind of young for a teacher to do so but again I the one teacher I've had a formal teacher that is who I remember as having really taught me something was in graduate school it was a professor Richard dick pal a yes so it's important to say the name yes who later became my de jour a thesis adviser yeah and we've become friends since then and well actually let me explain what he taught me by going back to I forget whether it was junior high or high school but when people learn geometry or when people are taught geometry they're thought that they're they're really learning to do rigorous reasoning and everything it's really precise and rigorous and when I was again either in high school or junior high school I became across the proof quote proof that all triangles are isosceles have you heard that yes I'm aware of that okay so people who aren't aware of it should look it up on the web and the fallacy in the proof is that it comes because we depend on the pictures that we draw in the ordinary plain geometry proofs yes and proof by pricked picture is not rigorous and that proof of that all triangles are isosceles is the clear demonstration of that so that led me to an interest or a predilection for algebra both you know Elementary and I guess it was called advanced algebra and in high school and algebra group theory stuff like that and in college because I knew that every proof in algebra or at least in group things like group theory couldn't be made completely precise and everything reduced to axioms and I really like that yes and what dick Palais showed me was that everything in analysis analysis is the generalization of calculus and he showed that that could be done completely rigorously and knowing that that could be done completely rigorously made me realize that all of mathematics could be done completely rigorously and that has influenced his enormous li influenced my career wonderful I'm gonna dial back just a bit in time to the graduation period from high school not after the graduation but the decision about the next step and where to go are you already in your mind a mathematician but by the time you're finished bronc science well actually when I was in high school I had sort of assumed that I would become an engineer because that's what people did you know to make money right and I remember at some point why mention that to a classmate he said to me you're too bright to be an engineer and I thought about her and said oh so then I decided that I would become the physicist oh and I saw when I went to MIT I was the intent of becoming a physics major a physics major yes and I'm not sure why I can't remember how I slid from physics into mathematics I remember or ascended depending everything interesting that I but I thought they'd have the direction it happened and early enough for you to then focus on mathematics and MIT or was that going to be later were you essentially studying physics at your whole time at MIT well I think the situation was that I was taking required physics courses but I'll be taking math electives ah I mean that's my recollection yeah and I thought sure how many electives there were yes but well I guess also that yeah I guess I was taking math courses that a physics major would not normally take yes but that was partly because since I taken advanced placement exam got me out of elementary calculus that gave me at least one elective extra elective that I was able to do taking math and the thing that if I actually switched me from a physics major to a math major is that in those days physics majors had to write an undergraduate thesis and math majors didn't of such circumstances many life decisions are made so you know but by the time I graduated from MIT it was clear that I want them to be a mathematician which meant becoming a math professor why didn't you stay at MIT for the next stage did you search the world for the right kind of department how calculating so to speak it's a pun but how calculating were you about the next step and which graduate program to enter well I entered Brandeis probably for two reasons first I was told that it had a bright young math faculty well so there was no problem getting in but because it wasn't in the top tier University yes on the other hand I think that the only University that well the only University I didn't get into and probably the only major one that I wouldn't have gotten into was Princeton as they had a very they were very selective and and you weren't yet a star well my grades weren't that good but that was mostly personal reasons and not involving math or this courses but humanities courses and the other reason for choosing Brandeis is that I felt that there will be less pressure there and it was a time in my life that I thought I would I was getting doubtful about somewhat doubtful about mathematics and so I felt that that would be a better place for me and
in fact it was so you got in as you did most places you went to Brandeis at what point I mean a graduate student has to be more directed than an undergraduate joining a school so what are you deciding which direction in mathematics or what is being decided with a mentor or professor well the first couple of years there was pretty much a set curriculum and afterwards I went through a period which I didn't know what I wanted to do and Brandeis was very good about just letting me drift I'm still keeping behind as a student fellowship real I realized afterwards that because they must have realized that I was really smart yeah so one thing is that I didn't realize until quite recently how smart I was yes that's important and the actually there's a paper that hits at that the I don't know if you're aware they it's the dunning-kruger effect a couple of psychologists wrote a paper that purported to show that people who aren't good at something think they're better than they are ah the people who know my Trent my translation of that is that give me stupid people think they're smart because they're too stupid to know that they're not yes yeah but they also suggested that didn't do any experiments about that there might be a different effect that people who are very good at something don't realize how good they are because they think everybody finds it that easy and that was the case definitely the case with me it was not that I thought that I was unusually smart right it was that I was really would be really puzzled by how other people had so much trouble understanding some things got it got it my version of what you just said it may not be the exact point but it supports it is the famous statement or assumption that people have which is that if you're really smart you know what you don't know mmm and that would lead to it again a kind of uncertainty but in any case you were not yet aware of what your capabilities were is that a way that will say it well I think I was aware of my capabilities I would think we more accurate to say that I wasn't aware that other people didn't have those capabilities God God no as in a professional level of study you have to do a thesis you can't get out of the thesis now you're incorrect it's going who is directing you how are you choosing okay well a little bit more background please at some polat's some point I left Brandeis and went off to teach math for four years at a small college in Vermont all borough college I'm supposed to give names and at about that time I thought that I wanted to do physics and basically what I did is I I think I was encouraged by somebody oh I don't remember whom I would walk into physics professors office and say you know what should I read you know I want to learn this and they were very you know very polite and very helpful and so I did some of that and and I went back to Brandeis it was with an intention of writing a thesis in mathematical physics okay and I came the crime across and that's a problem or I somewhere read about something that wasn't known and I thought that's an interesting problem and I'll try to do it do something about it and there was nobody at Brandeis who was a who is a specialist in the area that was required and required party differential equations and so by some mechanism that I don't remember I was put in touch with a professor at MIT and I have to admit that my failing memory is not sure but I think it was Professor kotake I would have to look at my thesis too but I started working with him and it quickly became apparent that what I the idea that I had wasn't going to pan out but he had a problem in his back pocket and suggested I work on it and I did and came up with a theory a thesis and I came up with some resultant partial differential equations and I think it was a probably a quite minor result oh I'm sure it was they're certainly not earth-shaking and i'm suspect bryce you know quite minor but sufficient for a thesis and right so I wrote my thesis on partial differential equation all your future work and direction is not really the result of the problem you look at it thesis right in fact I know absolutely nothing about partial differential equations except what was in my thesis really very interesting so many others really built on that okay you you got your PhD yeah but now I should then rewind yes you go back to my high school days yes and when I was probably a junior in high school possibly a senior got interested in computers I read a book on what was about well it involved boolean logic and and I think also circuits so you know basically elementary digital circuits and I got interested in computers from that end and even with a with a friend built a little 4-bit counter I think it was the and I remember a with and those were the days with vacuum tubes and it was built with vacuum tubes that I got from IBM because I had for some reason or how I did it I have no longer remember but I walked into IBM probably the they had a like a showroom in with in downtown Manhattan or with computers that you know in big glass windows open to the street and I walked in there and in those days they they didn't wait for it they wouldn't wait for tubes to burn out they would just replace all the tubes in the computer on some schedule and so they were available right and so I got the those tubes so that you know there were no that was still good but no longer being used and that's what I built that they were probably Charmin but this young fellow walking in and asking for them so how good okay so I mean that can that was just a little digital site you know of no interest but it did get me started interested in computers and when I graduated through some program of run by New York City I wound up getting a summer job at con Edison the electric utility in New York and they put me in some office that was doing something totally you sleep oaring but they had a computer and I managed to get myself
transferred to the computer department where I would was running tapes that is in those days you ran a program you would you first need to mount magnetic tapes that were used for input or output and then you would load the punch cards and a hopper and run the program and so you know that was my job but in my spare time and in the computer spare time and in those days when people went out to lunch the computer was sitting idle and so in its spare time I learned to program that computer and then for the next and it was clear to the people around there you know how smart I was it and so the next I forget it was two or three summers I worked as a programmer in the summer at Canada so college and in the summer you worked as a computer as a program right and it never occurred to me that I mean there was about rear in it well it was clear that there would be a career in programming but there was no such thing as computer science in those days it never even occurred to me that computers would be a subject of academic interest right but when I went back to Brandeis after teaching in Marlborough right oh I should say that in also while I was at Brandeis I guess like maybe I was wrong to say that they kept supporting me as you know with fellowships I think that for a couple of years they didn't support me at the fellowship but I was got a part-time job working at the mitre corporation and there was initially programming but it was programming on a new computer that was being built and I started doing what these days would be considered you know system building or villages considered a a computer science discipline well though to me it was just programming right and then when I came back to to go to Brandeis yes we're from depends on degree I also supported myself by working part-time it's time at Massachusetts Computer Associates or compasses of the school and in the course of that and a compass was a company that their main source of income was building Fortran compilers but they also did some but I guess you know was what's called research at the time for ARPA they now later DARPA the Defense Army Research Program associations the people who started the internet and in fact we're starting the internet at that time although I didn't know it and the course of that at some point I well I did some work which was actually when you will be called research and produced I produce a publishable paper and at which point they first published a paper on that but at any rate the I did some work for them it was actually connected to a Fortran compiler about executing instructions in parallel yes and what I did was it seemed pretty trivial but it was basically a simple application of linear algebra but since the people working there nothing about linear algebra you know it seemed miraculous to them and so at some point well after I got my degree yes I had always assumed that I would go and become a professor in this case saying that male professor since that was what would you were training for yeah well though I'm not sure whether I thought that computing would be of interest yeah I thought there might be a relationship between mathematics and computing because I had discovered something which had been discovered already about you know something yes it was actually some property of differential equations that made a certain way of doing the computation more efficient than another right and so I didn't have any clear idea of what kind of math I would do but any rate I had an offer from University of Colorado to teach math and at that just that was you know right about to accepted excuse me of course compass said we're gonna start an office in the Bay Area how would you like to work in our office in the Bay Area doing computer computer stuff yeah and because it was Colorado Springs rather than Oh aphasia sets in the town where the main a Boulder the West Was Colorado Springs rather than the Boulder I decided to go to Bay Area excuse me okay well almost you know about you know a few weeks after I had you know it said no to Colorado compass decided that though they were not ready to open their Jolla California office but why don't I go ahead and out in California and work by myself until they come out there you really made that decision this is such academic heresy to turn down a position at the University and go to what isn't even a job in the end yet and well now it was a job a new hood but they you said well the day they would they then pulled the pulsar Exodus well well obviously if they would have let me you know we happy to have him to work for them and in Boston yes but but they said that since well I mean I probably knew that you know there was the Bay Area that was an attraction for me they said okay we'll let you go out there and work by yourself until we open the office and the reason they were willing to do that is that it I want to know that work I told you I did about doing about parallelizing things based on linear algebra right I had actually convinced them to let me spend a month I forget whether it was one month or two probably one month in New Mexico at a friend's place and work on it there and since you know I had done that and actually work them came back with something useful this they had enough confidence that they figured I can work my myself well the upshot was that they never did open that office in in California but for let's see from 72 to 77 I was there California branching out and you were supported by the company Yeah right but you were working by yourself yes and it pretty much turned out to be on whatever you know what I felt like sorta yes and I mean there it was paid for by research grants on the government but it's still taking a chance and giving you free rein it's like a dream it's like a Research Institute way before one got these position well except it was being myself and that that's not a great way to be especially in the or starting researcher but I did
make some connections with people in the Bay Area and not a bad time Stanford yes and Berkeley to her Stanford principally probably Berkeley and at Xerox PARC I don't remember the I don't remember the well okay let me continue that at 1977 the campus decided or some bean counter at compass or something decided that you know they couldn't cope with me working in the West Coast and so I had to move to the East Coast and so I left campus and it's good started working at SR I oh it's a big question maybe too big but what is the general state of computational thinking at this point or analysis what what do we know in the world at the point where you are gravitating more and more to computer analysis is it as you look back a very second period questions in the air ambitions for the field any any broad sense of that well I can read the history books as well as you can say what was going on but in your head well it's a question of what I was aware of what were you aware of and okay so it was aware of some things even while I was working at compass I remember I got a paper that was written by a couple of guys at BBN which led to my time clocks paper which is the paper that I'm most known for no question and what I don't remember is how much of my contact with other people in the Bay Area was when I was working in compass and how much was after I start like this all right after I started an SSRI I would then it was plugged into a community I know we had contracts where gun and and all of that stuff and I was not I would not it's not completely free to work on what I wanted right but was that paper the Dijkstra I'm probably mispronouncing that what was the paper you said that started you in the path of thinking that led to the time clock no no but was a paper by two people Paul Johnson and Bob Thomas at BBN okay and you know hardly anybody who's heard of them now but it led to quite an interesting series of thoughts in your case so what was the paper approaching or what was the problem it was suggesting or well okay the problem they were suggest thinking about yes is they had in the database world I presume people know what a database is right it holds people's data and they were probably one of the first people to if not the first people to think about distributed databases namely where you had copies of the data were kept in multiple locations yes and what they were looking at is the the problem of synchronizing those different copies of the data and there was they had an algorithm that did it and I realized that their algorithm wasn't quite right not in the sense that it was you know formally and correct but that it was lacking a it had the property or the lack of property that two different operations that should have appeared and have been done in one order wound up being done in the reverse order and I was able to correct their algorithm so that that didn't happen and also even more importantly is I realized that that solution was not just for distributed databases but could provide a solution for an arbitrary distributed system yes I understand so that's one of the product that's the type of problem that was going around and yeah I think it was in 1976 oh god no I don't remember for 76 or 77 but I attended a workshop at there's not a SIL amar oh where was it at any rate the I Triple E had a Lake Arrowhead I think it was an annual workshop and there I met I well I remember Jim Gray giving a talk about a particular problem involving distributed systems and I'm not sure if that was when I met Jim Gray or if I'd already known Jim Gray from the Bay Area but so that's the sort of problem and also the stuff that was going on in Sirach spark which is people Marta where they were they invented you know the Macintosh and yes the whole idea of personal computing and also not just personal computing but personal distributed computing right which is your your the focus of your interest and in fact it's the little footnote that the at the time when compass was letting me go I applied both well I applied to to Berkeley well I talked to both to Berkeley Stanford Xerox PARC and SR I and when I first talked to Stanford they didn't seem to be interested in me people at Berkeley were quite interested in me but that was I was not really serious seriously applying and because I really preferred working in industry can we talk about that for a moment because this decision particularly in computer analysis of what everyone chooses to work in industry or academia or both is it quite important what is the difference in the circumstance of the research oh I'm not gonna say I can't say anything in general also I can assure me for you that at that point I still didn't really consider Computers Computers hey an academic discipline and so I couldn't imagine I mean to me it would mean you know my image of it was teaching programming right and that Jen did law and I didn't even say you know it just didn't seem appropriate that programming is something that you know you know should be taught at a university any more than I mean any manual trade right right understood so that's that was the main reason why I wasn't seriously considering Berkeley perhaps if I had I don't I don't know if they I I can't say whether there's anything they could have done that would have convinced me that you know computer science was a real life was the write us a play no it was just something you know I was in my head but at any rate the interesting part is that a Xerox PARC didn't make me an offer right and the number said eight years later I wound up working for a deck Cirque the system Research Center of Digital Equipment Corporation which was basically the people the refugees from Xerox PARC who had moved there and you know when I'd asked him about why they didn't make me an offer the official reason was that they thought that they would be able to get the benefit of my results by reading my papers they didn't have to hire me and I never believed that and I think there was a I think there was a feeling probably that I just wouldn't fit into the Ciroc spark culture which may have been a good good for both both sides you you certainly found a happy situation to be in
yeah on the other hand you know maybe the world would be using latex rather than word had I been at Xerox PARC and you know I would be flying my own 737 and going on to the flying on the space station wonderful because we don't have so much time I'm gonna press what I would normally do which is ask for what I would call Eureka moments now the first Eureka moment I would ask for it it probably wasn't a moment it's a process it was weaker moment you know you Eureka Eureka Eureka moment so at what point you figure out and I understand that wasn't just one point that computer the inquiry into the computation was not just a programmers universe but one were the rich analytical possibility because you certainly there was there was no Eureka moment was no Eureka it just you know it came gradually and at some point I just sort of said to myself oh I'm a computer scientist okay that's ahead I can't even remember when that moment was but it wasn't Aminu I wouldn't I didn't think of it as a you Rica moment it's just oh so that's what I've been to the right answer I mean it's how you thought of it the other thing I want to ask before we really get to the timeclock moment again not a moment but a process of maybe Eureka maybe not is the broader question again I'll ask it it may be interesting or not and that is just this difference if there is one or borderline or blending of the computer analysis world and the world of so-called pure mathematics it's often discussed people often say I am this not that how do you think about that link between mathematical inquiry and computer analysis I think the best answer but not as very satisfactory one is that I don't in the sense that it's I don't think about philosophical questions like that understood and as a matter of fact I regard one of the secrets of my success plea has been not thinking of grand philosophical questions but in looking at little interesting problems okay very interesting actually so there you are not thinking about mathematics in the future computer science but doing the work tell me a little bit about the the work that led you to the time clock well actually I would rather not talk about that okay the point because take up that something it was not a question you asked but a question I would sort of like to answer these in the sense of the relationship like between mathematics and programming yes and something that I realized well something that I in some that as because of my background in mathematics I would do naturally which is to approach a problem for example the synchronization of two database right right not as a programming problem but either a mathematical problem or a physics problem the but they're not separated because we know in physics the way you should think about a physics problem is in terms of mathematics yes now math you know that you know physics is not a branch of mathematics because the difference between mathematics and physics is that mathematics in physics mathematics provides a model of the real world yes it is not the real world and the difference between a physicist and a mathematician is that a mathematician could look at models that he just thinks are interesting at least the pure mathematician whereas the physicist needs to find a model that accurately describes what he's looking at exactly and there is no single mathematical model of any real world system I mean models are created for a purpose so for example when you study celestial mechanics or usually you consider a planet a point mass and that works fine for predicting you know the orbits of the planets and if you want to weigh to point your telescope at a certain time to see one on the other hand it's not a very useful model if you want to talk about the weather on a planet right and what I've been doing all my life but becoming in some sense more aware and trying to make it more precise and formalize it is thinking about programming problems not in terms of code in terms of programming but in terms of mathematics yes and that well for example what I've realized and amazingly few people seem to is that an algorithm is not a program an algorithm it's a higher level abstraction it's that can then be implemented with lots of different programmers and what I've discovered is that the best way to get to think about algorithms and to describe algorithms is in terms of mathematics not in terms of programming language concepts things that and well I've developed the language called TL a-plus yes which is basically to allow engineers to write mathematical descriptions of the algorithms that they're writing now but by algorithms are also not necessarily the algorithms that you will find in a textbook but a high-level system design isn't a sense an algorithm because it's an abstract description of a lower-level program systems design is different from differ from the algorithms that you see in textbooks because they're very specific and they're not you know useful for much other than the particular system to describing but it's the same thing and therefore you should think about them in mathematics so TL I plus is the language that allows them to both think about their higher level designs in mathematics but also apply tools to check them at that higher level that's now that was the end of a thread that was coming from someplace and I forget where it was coming from but as then okay so another thing what I've realized and what I've observed is that thinking about algorithms or high-level designs of systems in programming languages rots your mind to say it impolitely it constrains your thinking and that learning to think in terms of mathematics rather than in terms of programming language concepts improves your thinking and improves your system designs yes and I will quote you know one thing that that I learned welcomed into details one case where people were designing a an operating
system for something that had designed an operating system that or something that flew on a spacecraft and they were redesigning it and for reasons that are not completely certain they decided they wanted to write a high-level specification of of them to operate new of the new version before they implemented it's something that's seldom done and they decided to write in ante la plus and the end result was that their second version of the system now you build second versions you know that they expand you know they grow well the second version of the system had 1/10 the code of the original system that had been float and the original system was flowing on a spacecraft so they were not you know profligate Wistar who you know with code right of course and they credit that to having written their high-level design and they say in TLA plus but I will say it's because they were thinking mathematically it's wonderful um we're close to the end but I'm going to ask another version because it's another period at the moment now what are the interesting problems issues that you're addressing or you think the field is addressing that may result from some of your insights I there may be a lot there may be nothing that you want to talk about but I here's the opportunity and well first of all these days I do very little thinking about problems in the sense that you know I don't I do very little research occasionally I come out with little pieces of things that are interesting that I would you consider worth publishing a paper and yes they will usually appear on my publications page on the web because I don't want to go through the hassle of you know putting them in print somewhere and Journal that won't be seeing this by as many people as go to my website right but my primary occupation is trying to get people to think mathematically about programming but that's not the question you ask the question you want to know about the problems that other people are thinking yes that that you are noticing or interested in and well what clearly these days is the big problem that is everybody who's interested in in his AI and what I see is the as a major problem is that well AI solves problems that people were never able to solve because they didn't understand how to solve them and what AI does is gets around that problem by basically writing programs that we don't understand right now you can't reason mathematically understand you can't understand you know reason reason about something if you don't understand it yes so for example we would like to be able to gain to be able to write some mathematical model that will allow us to prove a theorem which can be interpreted as saying that this autumn of automobile is not going to run down a child right but we can't do that because we don't understand the program that's driving that car yes and the that's worrying me well there's the obvious well obvious problem for people designing you know building cars but I see a more generic problem there most of the work people do well you know when I say you should think mathematically about something and I say you shouldn't you know write a mathematical specification before you start well I say you should and I always say that you should write a description of what a program is going to do before you write the program because it's only when you write something do you know if you really understand what you're talking about okay but for most of the programs that people write that's that specification is is really simple you know it takes this piece of data and moves it over there and does this to it right and but it's a very small fraction of the program of the programs that get written that require a real mathematical specification for example run written in ela plus now but that large amount of dull programming is I think it's inevitable that it's not going to be done by people any longer it's going to be done by programs and there are two ways that that might happen one is we will develop better techniques from go for going from a precise description of something to the code yes and the other possibility is that we will build AI programs that allow people with and that requires that people be able to write precise descriptions even of those trivial things that yes doing this and the second approach is going to use AI to take imprecise specifications that people write and produce code from them yes and then we're going to be in this situation that we're going to rewriting programs that we'd have no idea what they do yes and that's a scary prospect I mean I understand that driving a car there's you know we cannot write a mathematical model for it and gonna have to live with that but I would hate to be in a world in which we don't I don't know what my bank is going to do into something because no bank has no idea what the rooms are doing yes and and that seems to be the world were well approaching and the only way I think to avoid it yes is to get people to be able to specify things precisely yes and that is not being taught anywhere basically yes the I think you know people say that they should be teaching programming in junior high school or something I think that's a great idea but they're but people are not teaching programming in junior high school they're teaching coding and coding the actual writing of code should be the trivial part of programming yes the hard part of programming should be understanding having this mathematical model of what it is that your program is supposed to do and that's not the taught and that's what needs to be taught and that's because people in academia have to understand that programming is more than just coding and they don't the people who teaching programming don't understand the difference between programming and coding that is a wonderful last word thank you very much thank you [Music]