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"Harry, let me verify that your Time-Turner hasn't been used," said Professor McGonagall.
"LOOK OVER THERE!" Harry screamed, already sprinting for the door.
Film about Stanislav Petrov
I searched around but didn't see any mention of this. There's a film being released next week about Stanislav Petrov, the man who saved the world.
The Man Who Saved the World
http://www.imdb.com/title/tt2277106/
Due for limited theatrical release in the USA on 18 September 2015.
http://themanwhosavedtheworldmovie.com/#seethemovie
Will show in New York, Los Angeles, Detroit, Portland.
Previous discussion of Stanislav Petrov:
http://lesswrong.com/lw/jq/926_is_petrov_day/
In response to
Harry Potter and the Methods of Rationality discussion thread, March 2015, chapter 116
In response to
comment
by
on
Harry Potter and the Methods of Rationality discussion thread, March 2015, chapter 116
Harry can just claim to have already used it that day for an innocuous purpose, like studying or something. Sure, McGonagall could accuse him of stupidity because that leaves him unprepared for an emergency, but pleading guilty to stupidity is easy. (Well, easier, anyway.)
In response to
Harry Potter and the Methods of Rationality discussion thread, March 2015, chapter 114 + chapter 115
In response to
comment
by
on
Harry Potter and the Methods of Rationality discussion thread, March 2015, chapter 114 + chapter 115
Don't be too hasty, whatever you end up deciding! It's only been a day. A lot of people put a lot of thought into solving this problem, and it makes sense that their attitudes about whether the problem was too easy, or too hard, or whether they solved guessed the author's solution, or whether it's unrealistic, would be emotionally enhanced by the effort they spent.
Take a week, take a month, talk to people you trust.
I'm a postdoc in differential geometry, working in pure math (not applied). The word "engineering" in a title of a forum would turn me away and lead me to suspect that the contents were far from my area of expertise. I suspect (low confidence) that many other mathematicians (in non-applied fields) would feel the same way.
In response to
The Problem with AIXI
If you limit the domain of your utility function to a sensory channel, you have already lost; you are forced into a choice between a utility function that is wrong, or a utility function with a second induction system hidden inside it. This is definitely unrecoverable.
However, I see no reason for Solomonoff-inspired agents to be structured that way. If the utility function's domain is a world-model instead, then it can find itself in that world-model and the self-modeling problem vanishes immediately, leaving only the hard but philosophically-valid problem of defining the utility function we want.
There's also the problem of actually building such a thing.
edit: I should add, the problem of building this particular thing is above and beyond the already difficult problem of building any AGI, let alone a friendly one: how do you make a thing's utility function correspond to the world and not to its perceptions? All it has immediately available to it is perception.
Why couldn't two identical AIXI-type agents recognize one another to some extent? Stick a camera on the agents, put them in front of mirrors and have them wiggle their actuators, make a smiley face light up whenever they get rewarded. Then put them in a room with each other.
If you're suggesting this as a way around AIXI's immortality delusion, I don't think it works. AIXI "A" doesn't learn of death even if it witnesses the destruction of its twin, "B", because the destruction of B does not cause A's input stream to terminate. It's just a new input, no different in kind than any other. If you're considering AIXI(tl) twins instead, there's also the problem that an full model of an AIXI(tl) can't fit into its own hypothesis space, and thus a duplicate can't either.
Lots of humans believe themselves to be Cartesian, after all, and manage to generalize from others without too much trouble. "Other humans" isn't in a typical human's hypothesis space either — at least not until after a few years of experience.
AIXI doesn't just believe it's Cartesian. It's structurally unable to believe otherwise. That may not be true of humans.
Let me try to strengthen my objection.
Xia: But the 0, 0, 0, ... is enough! You've now conceded a case where an endless null output seems very likely, from the perspective of a Solomonoff inductor. Surely at least some cases of death can be treated the same way, as more complicated series that zero in on a null output and then yield a null output.
Rob: There's no reason to expect AIXI's whole series of experiences, up to the moment it jumps off a cliff, to look anything like 12, 10, 8, 6, 4. By the time AIXI gets to the cliff, its past observations and rewards will be a hugely complicated mesh of memories. In the past, observed sequences of 0s have always eventually given way to a 1. In the past, punishments have always eventually ceased. It's exceedingly unlikely that the simplest Turing machine predicting all those intricate ups and downs will then happen to predict eternal, irrevocable 0 after the cliff jump.
Put multiple AIXItI's in a room together, and give them some sort of input jack to observe each other's observation/reward sequences. Similarly equip them with cameras and mirrors so that they can see themselves. Maybe it'll take years, but it seems plausible to me that after enough time, one of them could develop a world-model that contains it as an embodied agent.
I.e. it's plausible to me that an AIXItI under those circumstances would think: "the turing machines with smallest complexity which generate BOTH my observations of those things over there that walk like me and talk like me AND my own observations and rewards, are the ones that compute me in the same way that they compute those things over there".
After which point, drop an anvil on one of the machines, let the others plug into it and read a garbage observation/reward sequence. AIXItI thinks, "If I'm computed in the same way that those other machines are computed, and an anvil causes garbage observation and reward, I'd better stay away from anvils".
In response to
The Problem with AIXI
It's really great to see all of these objections addressed in one place. I would have loved to be able to read something like this right after learning about AIXI for the first time.
I'm convinced by most of the answers to Xia's objections. A quick question:
Yes... but I also think I'm like those other brains. AIXI doesn't. In fact, since the whole agent AIXI isn't in AIXI's hypothesis space — and the whole agent AIXItl isn't in AIXItl's hypothesis space — even if two physically identical AIXI-type agents ran into each other, they could never fully understand each other. And neither one could ever draw direct inferences from its twin's computations to its own computations.
Why couldn't two identical AIXI-type agents recognize one another to some extent? Stick a camera on the agents, put them in front of mirrors and have them wiggle their actuators, make a smiley face light up whenever they get rewarded. Then put them in a room with each other.
Lots of humans believe themselves to be Cartesian, after all, and manage to generalize from others without too much trouble. "Other humans" isn't in a typical human's hypothesis space either — at least not until after a few years of experience.
In response to
Anthropic Atheism
This is very well-written, exceptionally clear-headed, and, I'd suggest, Mainworthy. This kind of thinking does indeed seem to be what several have/are converging upon, including, IIRC, Wei Dai, Eliezer, some SPARC attendees who were thrown anthropics to try, possibly Carl Shulman, and presumably many others (e.g. other advocates of UDT and its offspring). Anthropics may well be/become the best example of LW rapidly solving/making major progress on a significant open problem in philosophy and reaching consensus before mainstream philosophy manages to do so.
It really does seem to me that the massive confusion around Doomsday is a result of people who are very smart and even good at reductionism (e.g. even Bos(s)trom, though I've by no means read all or even most of his stuff) lapsing and thinking about anthropics in such a way that they might as well be talking about souls.
That said, as best I can tell, Eliezer has remained mysteriously silent on Sleeping Beauty and Doomsday, which makes he hesitate slightly to declare them solved. (E.g. I'd expect his endorsement of a solution by now if he agreed and did not feel confused.) And specifically, last I heard, Eliezer held probability theory as above vulgar things like betting or something like that, so the lack of an obvious way to reconcile that view of probability with the dissolution of Sleeping Beauty in this post and the one I linked gives me pause. (This could be a failure of reductive effort on my part, though.)
Agreed about Eliezer thinking similar thoughts. At least, he's thinking thoughts which seem to me to be similar to those in this post. See Building Phenomenological Bridges (article by Robby based on Eliezer's facebook discussion).
That article discusses (among other things) how an AI should form hypotheses about the world it inhabits, given its sense perceptions. The idea "consider all and only those worlds which are consistent with an observer having such-and-such perceptions, and then choose among those based on other considerations" is, I think, common to both these posts.
In response to
Open thread for December 9 - 16, 2013
What are community norms here about sexism (and related passive aggressive "jokes" and comments about free speech) at the LW co-working chat? Is LW going for wheatons law or free speech and to what extent should I be attempting to make people who engage in such activities feel unwelcome or should I be at all?
I have hesitated to bring this up because I am aware its a mind-killer but I figured If facebook can contain a civil discussion about vaccines then LW should be able to talk about this?
(I haven't seen the LW co-working chat)
If you want to tell people off for being sexist, your speech is just as free as theirs. People are free to be dicks, and you're free to call them out on it and shame them for it if you want.
I think you should absolutely call it out, negative reactions be damned, but I also agree with NancyLebovitz that you may get more traction out of "what you said is sexist" as opposed to "you are sexist".
To say nothing is just as much an active choice as to say something. Decide what kind of environment you want to help create.
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When will Harry tell Hermione the truth? I feel like he should insist she learn occlumency first.