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  • >> Sean: We have had some questions in from some of the fans, some of the viewers of Computerphile

  • And we thought it would be a be nice idea to have a

  • chat and you tell us what you think. So, I've picked a few [questions] that maybe hopefully will

  • go together and and we may well do some others at another time. We're going to kick

  • off with this one here from Patrick Orton, who I think you may actually ...

  • >> DFB: Yes! Hi Patrick! He was one of my project students a year or two ago. Yeah! Hi Patrick!

  • >> Sean: He's asked four questions. So we'll whip through these before getting on to some others.

  • So: what is your favourite area of computer science ? >> DFB: my favorite area of

  • computer science? Well, it's split into two really. Although it's very

  • very applied computer science I really do like everything to do with digital

  • documents - right through from the sort of XML structural stuff right down to the

  • nitty gritty typesetting, fonts and PostScript stuff. I love that. But if you

  • were to say is there an area I like doing videos on which fascinates me

  • - although it's not really my specialist area - the answer is, what we're doing at

  • the moment, which is Regular Expressions. I think they're fascinating! They're so

  • easy but so difficult. You get Regular Expression wars between commenters.

  • They're wonderfu!lThere's a way to go yet on REs before we finally say

  • "That's enough!" Yeah, >> Sean: well, it's interesting because you kind of roll these first two

  • questions together, so we'd ask the favourite area to work in and the area you're most

  • interested in. What's the area of computer science that you'rer best at?

  • >> DFB: Do you know that's a very good question Patrick. I can tell you are one of the

  • students that I supervised. How well you know me! The answer, truthfully, is that I

  • don't consider myself an outstanding computer scientist in any of the areas.

  • I suppose you could say, insofar as I have some expertise, the whole digital

  • documents / electronic publishing, low-level, PostScript/PDF stuff, yes.

  • But actually what am I really best at? It finally dawned on me, and thanks to you

  • and Brady, you have given me the ability to exploit this. I'm best at explaining

  • things to people and, as I've often said, I, when I was younger, had to teach myself

  • and there's [potentially] a whole extra episode on why, to be competent in a wide range of things.

  • And being forced to teach something is the best way to learn it. So I think I am

  • good at that. The problem I had was if I was like Brian Kernighan and had the

  • tenacity to write lots of books, that would have been a way to propagate my

  • expertise. I don't really have the patience to write books. What I wanted

  • was somebody to come and just talk to me and make videos from my waffle! And you

  • and Brady - honestly I remember that first visit, and it's been solidly downhill for

  • seven years ever since then, hasn't it? 2013? something like that yeah?!

  • >> Sean: Patrick also had a question, which connects to a couple of other questions, so I'm going to roll

  • these together if that's all right with you. What is the area of computer science

  • that looks to be most important in the near future? which connects to one

  • Richard Denton's asked about " ... your extensive history in the new field of

  • computer science, what direction is it heading in and Gregor who said: " ... which

  • area of CS will in the near future be used the most and which do you think

  • there's no future to? >> DFB: I'm not very good at futurology! I could list all of the

  • things which I've come across in computing and have said " ... that will *never*

  • catch on!" But then, six months later, it's the lead

  • topic in the whole field! Now I think, all right, let's just say recently the thing

  • this has quite taken my breath away has been the whole stuff about Neural Nets

  • Deep AI and so on. And now it's fascinating because ... I'll tell you what is the

  • most fascinating thing. You had Deep Blue playing chess basically by brute force

  • methods [looking mny moves ahead] and back in the 80s -- I don't play chess by the way but I do find it fascinating --

  • it was Deep Blue, IBM's Deep Blue, I think, that defeated Kasparov for

  • the first time, Wow! you know. And I felt: "Well it's just brute force and ignorance that [is]"

  • But on the other hand the moment you start doing neural networks, which

  • learn and adapt and once you start feeding in the fact that you can play

  • yourself in a computer rendering of the game. You know what they've done on GO

  • and chess and all that, now, is to say we don't just hard-code the rules and

  • look thirty moves ahead. We'd get it to find out what unlikely things have

  • come up, in me playing myself, where it just went berserk and went off on a tangent

  • And I thought " ... that's a lost game" But it wasn't! It found a back-door way in and

  • triumphed. And I think that's what took the GO guy - was it Lee Sedol - apart.

  • He just thought:" ... that's ridiculous I'm gonna win this one!" Then, about 20 moves later

  • he hadn't! And I think he found that shattering, and I can well imagine that.

  • And I think my understanding is very limited of this - is that the Deep Mind

  • people have now started applying all that they did to GO to apply it back to

  • chess. And don't use brute force just build up millions of games and let it

  • learn what's a good thing to do. And I think I'm right in saying that that

  • piece of software, using the neural net statistical whatever, is now more

  • successful than the original Deep Blue was, but I'm not sure. So what you

  • can say is [that] taming big data via AI is a tremendous area. It's I mean Big

  • Data is important and the degree to which you can tame it with so-called

  • AI is fine but the big question still is [this]. You go to the authors of these

  • "highly intelligent" programs but they're not - and you say: "Can it do 'common sense' ? "

  • "No! not a hope! it's brilliant at go because it's still a narrow and

  • well-defined field but don't ask it to pontificate on the state of politics in

  • the Western Hemisphere". It hasn't a clue! So, there we are, right, something that I know

  • I'm interested in. I know very little about but does seem to me to be a real

  • marker for the future. >> Sean: Maybe onto a different subject. We had a question from

  • Erik Stens and he said: "As engineers we all have our pet project. What have been

  • some of your hobby projects - computer related - that you're most proud of.

  • And would you tell us a bit about them all? >> DFB: Right! Well, I suppose I should say at the

  • start that one of the advantages I've got being the ripe old age I am, is that

  • I've been what's called an Emeritus Professor for well over ten

  • years now and that this does give me the ability to pursue lunatic things that

  • would never ever have got me promoted to Professor but I was there already.

  • >> Sean: can you tell people what 'emeritus' means For those who don't know those who aren't in academia?

  • >> DFB: What happens with Emeritus Professors is that it's basically a way of pension ah--you

  • off but in a gentle way. The idea of an Emeritus Professor - the Latin of course

  • means 'E' = 'out of 'merit. i.e. "because of merit" You are given this honorary position. It

  • varies very much as to which university are in as how active an Emeritus you

  • want to be, but for me, back in 2005, I came off the regular payroll

  • as a professor and 'cut a deal', as it were, where I will be brought back on a

  • renewable yearly contract to do fill-in teaching on stuff I likeds but the good

  • thing was: " ... with no major administrative responsibilities". So I took my pension I

  • got some extra top-up from the School of Computer Science and really, I think, the

  • last actual taught course I did, given that I formerly 'went Emeritus' in 2005,

  • I was still teaching classes through to 2013. And why did I change

  • tack then? Well, once upon a time, two hirsute guys came into my office and said:

  • "Hello, we're Brady and Sean. We're going to reshape your future" you've wanted to

  • find somebody idiotic enough to record your waffle?

  • That's us! Well, it's true isn't it ? I always love the teaching but to be able

  • to teach in a way like this - which would never have got me promotion to anything

  • had I tried to do it as a 30-year-old, you know. Which is why, in many ways, I'm

  • so glad that Steve {bagley] and Mike {Pound] are still happy to do it because it can be part of

  • what you do but it can't be the totality of what you do. And yet, for me now, it

  • really is almost a totality of what I do. You've given me an avenue to spread the

  • gospel or something. Yeah! so that's what it means to be an Emeritus Professor

  • It's given me complete freedom to do, for example, the stuff we did rescuing the

  • banned paper [memorandum] about the Linotype 202 typesetter. Now, it was such a good

  • project because it was Brian Kernighan's work - [he's] virtually a Computerphile

  • regular now although the [corona]virus has confined him to the States for the moment -

  • but yes it was his work way back in the late 1970s

  • which had been banned from publication. A mutual friend of both of us, Chuck

  • Bigelow who's the co-designer of the Lucida typefaces.

  • [He] basically said, to both of us, we know him well. He said: "You two you should be

  • telling the story now - it's not sensitive any more". So we did all those videos on it.

  • But in order to get the story total I said to Brian: "What we have to do is

  • not just resurrect this memo, which was on yellowing paper that had been

  • photocopied in 1978. We've got to recreate it using modern PostScript/PDF

  • fonts technology at the quality that was innately there off the virgin-fresh

  • bromide that came out of the 202. And it's got to be really good and Postscript's

  • up to the job, you know, that is the the glue that binds it all together we can

  • we can do it but I wanted it to be a perfect resuscitation as it were. And

  • getting that last few percent right was just very rewarding, but very frustrating.

  • I mean we had it published. It's had very good reception. People love it when

  • they find it. But could I seriously have beem on the end of a yearly [personal] review

  • having to say this 'caper' that we did: does that count towards making me a Professor ?!

  • I I think my previous heads of department would have said: "No! it's frivolous!"

  • >> Sean: It's interesting because it kind of leads on too many other questions which is

  • from Jonathan Lystrom, I hope I'm saying that right: "Ask Professor

  • Brailsford how he learned to be so pedagogic well-versed and an absolute

  • joy to listen to". That's going to be nice to hear. I assume I'm saying 'pedagogic' right?

  • >> DFB: I think you are. Well, thank you for the implied flattery - is it Jonathan?

  • Thank you. The thing is, of course, that my style doesn't appeal to everybody.

  • Some people find it too waffly, too 'hand wavy', and although I love explaining

  • things to people I just love it when I get real experts come at me - just the odd

  • one - and it's always: "David, you did a good job. But you were on thin ice! You

  • very nearly started telling things that were all flatly untrue. And I thought, I

  • thought, this is it! He's gonna fall down into the ice-pit ... at the

  • last minute, Oh! you know you rescued yourself! You didn't tell an untruth but

  • it's not the way to explain it!" To which my retort is: "If I get people saying 'I

  • didn't remotely understand it until [you] explained it [your] way' ", then I rest my case

  • I was new I enjoyed teaching but the answer is very simple when we were

  • turning from a Computer Science Group in a Maths Department, this was in 1986, to

  • being a full-fledged Computer Science department eventually, it didn't dawn on

  • me - because I was leading the charge on this - that we'd actually have to teach

  • across the whole range of Computer Science. So we took a first few Single

  • Honours computer science students in 1986 and then it suddenly hit me that, by

  • 1989, we'd got to give them a full-blown Computer Science experience. And how many

  • people did I have? Six and that includes one technician and a pet cat [joke]. "Oh my lord, how are we gonna

  • do this?" And I said to people, I remember, [at] one of the first departmental meetings,

  • I remember saying: "Look, we are very very short-staffed. I think that the University

  • will help us out with one or two [extra academics] but it won't be as many as we need: Sorry folks

  • we've all got to be prepared to teach well outside our comfort zone!"

  • And that is the answer to the real question [which] is: "Why can you teach over such a broad range?"

  • I had to! I had to learn about Chomsky, Regular Expressions, Turing

  • Machines and all that because at the time I didn't have specialists to teach it

  • But it comes back to the main thing: I enjoy

  • teaching difficult things just by saying: "I found it [this topic] difficult, here's how I got to

  • grips with it" And if that style of explanation suits you then it's a

  • win-win situation. >> Sean: We've had a question from a very

  • familiar name here, Graham Hutton. Have you heard of this character?

  • >> DFB: Well, yes,you know it 'rings a bell' (!) >> Sean: If you could have invented one idea in computing what

  • would it be?" >> DFB: Again first obvious answer is : ... would it have been invention or would it

  • have been 'discovery'. Was it in some sense 'there already'? I have often thought about

  • this but the the stuff I would love to have been more involved in, I would love

  • to have been at the right place to be heavily involved in it: In the early

  • 60s to late 70s - it was over a long span is the whole area of Chomsky Types 3 anbd 2

  • which covers, really regularexpressions, [plus a single stack] when do they run out of steam?

  • What theorems can you prove about them? Now it's an area that we're

  • still coming back at, but the one person - sorry to be boring; everybody venerates

  • him for different reasons, still with us and I reserve the right to come back and

  • do a biography of him, in some sense, from my knowledge of him: Ken Thompson. I mean

  • there were Regular Expressions invented by Stephen Kleene and, yes, they were

  • fine but not a lot of people understood them. But one of the people who really

  • understood them was not a sort of avowed, declared, theoretician but .... Ken Thompson -

  • the world's ultimate super-duper computer [system] programming practitione.

  • He just understood in a very very deep way what a Regular Expression could do,

  • and couldn't do. And, more to the point. there was a very important theoretical

  • paper by Dana Scott and Michael Rabin which

  • basically said: "These Regular Expressions give rise to automata diagrams, which

  • we've done [on Computerphile] but of course, a lot of these automata diagrams basically say:

  • "Well, what's the next character in your input stream? A letter 'a' ? Oh! I can go in three

  • possible directions [in this automaton] on an 'a' Which one do you want me to take?" And the trouble is,

  • if you guess wrong, you end up down a blind-alley. And you have to backtrack

  • out and you have to re-do and put back again every variable you set in trying

  • to analyze it. You've got a reset and that's massively expensive you see.

  • So, what Scott and Rabin did was to prove that everything that was

  • non-deterministic could - by an algorithmic process be turned into

  • a deterministic [one]. Except it might have a lot of extra states and it might have a lot

  • of extra escape chutes labelled 'empty' that took you down to a false ending. and

  • you had to build to cope with that . Ken kind of instinctively understood that, you know.

  • the idea that you could make it deterministic. This is what Lex does for

  • those of you who are into using UNIX tools. And I was just appalled and amazed

  • that that was possible. I thought I'd love to have done that but I would have

  • loved [also] to have had Ken's sure-footedness. In his favourite editor, QED,

  • he built in the whole deterministic/ non-deterministic thing. In ordinary UNIX

  • 'ed' he decided that the labour involved wasn't worth the candle, you know, and he

  • quite happily a- nd what better programmer to do it - said [that] at times, although

  • recursive backtrack is deprecated, a little bit of it - so long as you don't do

  • too much - I know how to do it. And he was just such a master programmer

  • he could make it work either way.

>> Sean: We have had some questions in from some of the fans, some of the viewers of Computerphile

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