I literally cannot make sense of this thread at all. Half of the messages are from someone who I would assume is a conspiracy-theory spammer. I could literally replace that person’s messages with things copy-pasted from Time Cube and get something about as coherent. Except other people in the thread appear to interact with that person and a quick glance at the group archive suggests this person is somewhat important to what they do?

Is this some sort of Poe’s Law parody group that I’m just not deep enough into the material to get?

The poster you’re talking about is Carl Hewitt. He has become a crank, and he denies various basic facts about lambda calculus, Gödel’s work, and Turing’s work. In this thread, he is complaining about Mark S. Miller’s proposed taxonomy for side channels and similar security issues, a work which simply tries to put names to certain common bug classes. Miller has written papers like this before, and just like how plan interference was first discovered in the context of capability theory, we might hope that other non-obvious bug classes can also be found via similar inquiries.

The main thrust of my post is to rigorously show that Hewitt is wrong to claim that actors are above and beyond Turing machines; we can indeed compute with actors using standard computers. This is something that he and I have argued about before.

I have owed this particular proof to the group for a few years; during an academic conference, I responded to an open unanswered question by noting that object graphs behave somewhat like hypergraphs, which can be lifted to categories. However, it wasn’t yet obvious how to mutate those graphs, and so it was an idle curiosity. The rest of the proof just snapped together last night.

The poster you’re talking about is Carl Hewitt. He has become a crank, and he denies various basic facts about lambda calculus, Gödel’s work, and Turing’s work.

Don’t argue with cranks, your life is worth more than that

Carl Hewitt is famous for kinda sorta inspiring the actor model of concurrency, which is used by Erlang and Pony and stuff. In the mid-00’s or so he went completely bugnuts crazy and has since been banned from ArXiv, Wikipedia, and then Wikipedia a second time. However, since he did influential work in the 70’s and 80’s people still think he’s an intellectual giant.

I especially dislike him because he’s ruined a ton of Wikipedia and C2 pages on CS history. Every year Wikipedia admins find like another two dozen of his sockpuppets.

He’s been vandalizing Wikipedia pages for the past 15 years with falsehoods like “Gödel was wrong” and “all modern logic programming was inspired by PLANNER” and “Actors are stronger than Turing machines”.

If you want to learn more, best place to start is the Wikipedia talk page: https://en.wikipedia.org/wiki/User_talk:Prof._Carl_Hewitt. That doesn’t cover everything; it missed a bunch of pages he vandalized, or that, after having been banned for a decade, he was finally unbanned in October 2016 and then had to be banned again three weeks later.

He gave a talk in Cambridge a couple of years back. I was excited to hear him speak, until about 5 minutes into the talk when it became clear that he was talking complete nonsense. It was pretty uncomfortable listening, he was making assertions that I’d expect any undergraduate to be able to disprove and no one wanted to interrupt because there’s no way of arguing usefully with someone that out of touch with reality.

I’m gonna try just because I have some time on my hands: because of this document people wondered “do we have a formal model of this?” as it would be quite useful to reason about the stuff. Then @corbin (please correct me) linked the “everything is an actor” premises to a category theory notion, there must be a category of actors (he goes on to sketch one) and it might have some properties (can this thing actually compute everything?). A category of actors could be a Turing category and this is where things are confusing, the category of actors as sketched would be typed but we know Turing categories to be untyped, contadiction.

Is this some sort of Poe’s Law parody group that I’m just not deep enough into the material to get?

I think that you picked up everything. The paradox of Turing categories is that all of the different types exist, but also they can be erased.

Like, given some object O, and a Turing object A, the arrows O -> A freeze elements of O as code literals. For example, if O were a natural numbers object, then the elements of O might be 42 or 100, and the corresponding elements of A might be "42" or "100". Similarly, the arrows A -> O are like evaluation of code literals, with "42" being sent to 42 and e.g. "anyRandomIdentifier" being sent to failure/partiality.

The effect of this is that an actor could both be fully strictly statically typed in the category-theory tradition, and also have the potential to evaluate code literals which could do anything, including representing elements who don’t belong to any type at all. I have mentioned this paradox before and given examples in C++ and Haskell.

Another effect, which contradicts Hewitt’s claims, is that actors can be truly Turing-complete; they can diverge.

I’m curious, who? (you can respond privately if you don’t want to say in public)

Jonathan Shapiro and Mark Miller are two of the main figures behind capabilites. Shapiro used to be a professor at CMU. Miller was done lots of work related to sandboxing for JS (at google).

Lots of Actor model stuff sounds crazy (since it seems to try awfully hard to be it’s own unique thing), but it’s definitely influential on lots of things.

Carl Hewitt is the guy behind the Actor Model of computation, which was a CS dead end. Notably, Steele and Sussman tried to implement it in Scheme and quickly abandoned it as pointless.

The Actor Model of concurrency was invented by Gul Agha, one of Hewitt’s grad students. Hewitt’s been taking credit for it ever since.

OK, this plus the “yeah, he really is that sort of crank” stuff makes things make more sense, because I was reading “Actor” as the concurrency model and not getting anywhere from that.

It’s pretty clear he’s referring to message like this, which have a typography and writing style with more than a passing resemblance to the Timecube website.

This entire “Universal Intelligent Systems” (also see video) thing seems to be missing some points. It looks like a mathematician thinking they can solve problems that are not mathematical in nature with mathematics.

I’ve seen his talks in person. They are much, much worse. But he keeps getting invited to prestigious places because he once did some interesting work. It’s kinda depressing all around.

I’ve seen his talks in person. They are much, much worse. But he keeps getting invited to prestigious places because he once did some interesting work. It’s kinda depressing all around.

I’ve been to one of these, and IMO the best part of the talk was when Hewitt got so caught up in his own conspiracy theory rant that he forgot where he was and literally fell off the stage.

I’m a contrarian (or maybe a partial crank) in that I think fear of the halting problem keeps us from doing a lot of really useful stuff, but it’s a pretty simple thing to grok, how could it be wrong/solved?

“Monster” is absolutely the right term for describing category theory. George Cantor the founder of set theory was a certified schizophrenic. Apparently for him set-theory was the proof of the foreskin-loving God. Ever since the word “infinite” has entered the dictionary dull theologians have been abusing the word, funnily God doesn’t have mass.

Godel’s theorem already proves that mathematics can’t have foundations because you get the infinite regress into whats the foundation of the foundation, who shaves the barber’s head paradoxes every time. I doubt if this paper gets it right. In physics or engineering the limits to such infinite regress are stopped by nature and deadlines, on whose basis we build things.

Apologies for the brief comment, but I find it fascinating that I knew almost immediately we were talking about category theory and the answer is “no”

I do not believe it is possible to explain why, though! As one cmomenter began to realize, this is a meta/sytem-talking-about itself issue. Perhaps you could define your way into proving it, but you’d just be left with loose threads at a higher level of abstraction. A system cannot contain a symbol that completely describes the system itself. This is semiotics, not CS.

A system cannot contain a symbol that completely describes the system itself.

Not my area of expertise, but isn’t Godel’s incompleteness theorem significantly weaker than this statement? If this were true, how could a compiler be self hosting?

That’s a representational question. that’s why I said this was semiotics, not CS. Your reply was about calculations: can a thing calculate itself? Sure it can.

Godel is something else entirely, a statement about the nature of categories and transforms in general, ie a computational statement.

It category-ese, the question was about categories of stuff. Your response was about transforms. In most cases these two are mirrors: a category is indicated by transforms, and transforms indicate the presence of a category. But not always. (And admittedly I’m doing a lot of hand-waving with my terminology here for sake of brevity)

Godel is something else entirely, a statement about the nature of both categories and transforms.

Right, Gödel’s statement is entirely about objects on the inside of a category/universe, but the interpretation which creates the paradox is always sitting outside. Indeed, the generic statement from Lawvere is mundane and talks of surjective arrows and fixed points in any category. It is only when we interpret these statements as being self-referential that we obtain the various paradoxes.

I literally cannot make sense of this thread at all. Half of the messages are from someone who I would assume is a conspiracy-theory spammer. I could literally replace that person’s messages with things copy-pasted from Time Cube and get something about as coherent. Except other people in the thread appear to interact with that person and a quick glance at the group archive suggests this person is somewhat important to what they do?

Is this some sort of Poe’s Law parody group that I’m just not deep enough into the material to get?

The poster you’re talking about is Carl Hewitt. He has become a crank, and he denies various basic facts about lambda calculus, Gödel’s work, and Turing’s work. In this thread, he is complaining about Mark S. Miller’s proposed taxonomy for side channels and similar security issues, a work which simply tries to put names to certain common bug classes. Miller has written papers like this before, and just like how plan interference was first discovered in the context of capability theory, we might hope that other non-obvious bug classes can also be found via similar inquiries.

The main thrust of my post is to rigorously show that Hewitt is wrong to claim that actors are above and beyond Turing machines; we can indeed compute with actors using standard computers. This is something that he and I have argued about before.

I have owed this particular proof to the group for a few years; during an academic conference, I responded to an open unanswered question by noting that object graphs behave somewhat like hypergraphs, which can be lifted to categories. However, it wasn’t yet obvious how to mutate those graphs, and so it was an idle curiosity. The rest of the proof just snapped together last night.

Don’t argue with cranks, your life is worth more than that

some people watch TV, some play video games… others, they have less conventional hobbies…

Carl Hewitt is famous for kinda sorta inspiring the actor model of concurrency, which is used by Erlang and Pony and stuff. In the mid-00’s or so he went

completely bugnuts crazyand has since been banned from ArXiv, Wikipedia, and then Wikipediaa second time. However, since he did influential work in the 70’s and 80’s people still think he’s an intellectual giant.I especially dislike him because he’s ruined a ton of Wikipedia and C2 pages on CS history. Every year Wikipedia admins find like another two dozen of his sockpuppets.

Do you mind sharing some details?

He’s been vandalizing Wikipedia pages for the past 15 years with falsehoods like “Gödel was wrong” and “all modern logic programming was inspired by PLANNER” and “Actors are stronger than Turing machines”.

If you want to learn more, best place to start is the Wikipedia talk page: https://en.wikipedia.org/wiki/User_talk:Prof._Carl_Hewitt. That doesn’t cover everything; it missed a bunch of pages he vandalized, or that, after having been banned for a decade, he was finally unbanned in October 2016

and then had to be banned again three weeks later.He gave a talk in Cambridge a couple of years back. I was excited to hear him speak, until about 5 minutes into the talk when it became clear that he was talking complete nonsense. It was pretty uncomfortable listening, he was making assertions that I’d expect any undergraduate to be able to disprove and no one wanted to interrupt because there’s no way of arguing usefully with someone that out of touch with reality.

it’s category theory

I’m gonna try just because I have some time on my hands: because of this document people wondered “do we have a formal model of this?” as it would be quite useful to reason about the stuff. Then @corbin (please correct me) linked the “everything is an actor” premises to a category theory notion, there must be a category of actors (he goes on to sketch one) and it might have some properties (can this thing actually compute everything?). A category of actors could be a Turing category and this is where things are confusing, the category of actors as sketched would be

typedbut we know Turing categories to beuntyped, contadiction.I’m gonna go with

maybe:)I think that you picked up everything. The paradox of Turing categories is that all of the different types exist, but also they can be erased.

Like, given some object O, and a Turing object A, the arrows O -> A freeze elements of O as code literals. For example, if O were a natural numbers object, then the elements of O might be

`42`

or`100`

, and the corresponding elements of A might be`"42"`

or`"100"`

. Similarly, the arrows A -> O are like evaluation of code literals, with`"42"`

being sent to`42`

and e.g.`"anyRandomIdentifier"`

being sent to failure/partiality.The effect of this is that an actor could both be fully strictly statically typed in the category-theory tradition, and also have the potential to evaluate code literals which could do anything, including representing elements who don’t belong to any type at all. I have mentioned this paradox before and given examples in C++ and Haskell.

Another effect, which contradicts Hewitt’s claims, is that actors can be truly Turing-complete; they can diverge.

I’m curious, who? (you can respond privately if you don’t want to say in public)

Jonathan Shapiro and Mark Miller are two of the main figures behind capabilites. Shapiro used to be a professor at CMU. Miller was done lots of work related to sandboxing for JS (at google).

Carl Hewitt is

theguy behind the Actor Model.Lots of Actor model stuff sounds crazy (since it seems to try

awfully hardto be it’s own unique thing), but it’s definitely influential on lots of things.Carl Hewitt is the guy behind the Actor Model

of computation, which was a CS dead end. Notably, Steele and Sussman tried to implement it in Scheme and quickly abandoned it as pointless.The Actor Model

of concurrencywas invented by Gul Agha, one of Hewitt’s grad students. Hewitt’s been taking credit for it ever since.OK, this plus the “yeah, he really is that sort of crank” stuff makes things make more sense, because I was reading “Actor” as the concurrency model and not getting anywhere from that.

It’s pretty clear he’s referring to message like this, which have a typography and writing style with more than a passing resemblance to the Timecube website.

This entire “Universal Intelligent Systems” (also see video) thing seems to be missing some points. It looks like a mathematician thinking they can solve problems that are not mathematical in nature with mathematics.

I’ve seen his talks in person. They are much, much worse. But he keeps getting invited to prestigious places because he once did some interesting work. It’s kinda depressing all around.

I’ve been to one of these, and IMO the best part of the talk was when Hewitt got so caught up in his own conspiracy theory rant that he forgot where he was and literally fell off the stage.

I feel bad, but fuck me that’s hilarious. Pure absent-minded professor.

I really think there should be a limit on how much we tolerate cranks in the CS space. I get that some people are contrarian, but still.

Contrarian implies some level of expertise. In a 2018 keynote I attended, he claimed he solved the halting problem.

I’m a contrarian (or maybe a partial crank) in that I think fear of the halting problem keeps us from doing a lot of really useful stuff, but it’s a pretty simple thing to grok, how could it be wrong/solved?

I believe his specific claim was “actors can have timeouts, so they’re guaranteed to halt”

Someone should do a psychological study on the people who use colors and typefaces like this

https://professorhewitt.blogspot.com/

I’m unfamiliar with SSRN.com - it’s an open-access site run by Elsevier?

SSRN is a pre-print site owned by elsevier.

I was just in the middle of writing a diatribe on OO/FP and this title caught my eye from the post,

“Vanquishing ‘Monsters’ in Foundations of Computer Science: Euclid, Dedekind, Russell, Gödel, Wittgenstein, Church, and Turing didn’t get them all …”

https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3603021

“Monster” is absolutely the right term for describing category theory. George Cantor the founder of set theory was a certified schizophrenic. Apparently for him set-theory was the proof of the foreskin-loving God. Ever since the word “infinite” has entered the dictionary dull theologians have been abusing the word, funnily God doesn’t have mass.

Godel’s theorem already proves that mathematics can’t have foundations because you get the infinite regress into whats the foundation of the foundation, who shaves the barber’s head paradoxes every time. I doubt if this paper gets it right. In physics or engineering the limits to such infinite regress are stopped by nature and deadlines, on whose basis we build things.

Apologies for the brief comment, but I find it fascinating that I knew almost immediately we were talking about category theory and the answer is “no”

I do not believe it is possible to explain why, though! As one cmomenter began to realize, this is a meta/sytem-talking-about itself issue. Perhaps you could define your way into proving it, but you’d just be left with loose threads at a higher level of abstraction. A system cannot contain a symbol that completely describes the system itself. This is semiotics, not CS.

Very cool. Thanks for the link.

Not my area of expertise, but isn’t Godel’s incompleteness theorem significantly weaker than this statement? If this were true, how could a compiler be self hosting?

The question is “Is there a category of actors?”

That’s a representational question. that’s why I said this was semiotics, not CS. Your reply was about calculations: can a thing calculate itself? Sure it can.

Godel is something else entirely, a statement about the nature of categories and transforms in general, ie a computational statement.

It category-ese, the question was about categories of stuff. Your response was about transforms. In most cases these two are mirrors: a category is indicated by transforms, and transforms indicate the presence of a category. But not always. (And admittedly I’m doing a lot of hand-waving with my terminology here for sake of brevity)

Godel is something else entirely, a statement about the nature of both categories and transforms.

Right, Gödel’s statement is entirely about objects on the inside of a category/universe, but the interpretation which creates the paradox is always sitting outside. Indeed, the generic statement from Lawvere is mundane and talks of surjective arrows and fixed points in any category. It is only when we interpret these statements as being self-referential that we obtain the various paradoxes.