First let me respond to Boris and Mark. I agree. Mark suggested putting Wikipedia in a canonical form, which would remove the distinction between lossless and lossy compression. This will be hard, but Boris made an important observation that useful data is generally compressable and useless data (noise) is not. I don't think the problem can be solved completely but there is clearly room for improvement.
Eliezer suggests putting a model of the universe on a USB drive and then running the model to predict how many fingers he is holding up. Let's assume that is possible. Stephen Wolfram suggests the model, if one exists, might only be a few lines of code. http://en.wikipedia.org/wiki/A_New_Kind_of_Science But we must solve a few other problems first. 1. It may be hard to find such a model. We cannot tell whether the apparent randomness of quantum mechanics is truly random or generated by a deterministic, but random appearing process. This happens in cryptography. The only way to distinguis between true random data and an encrypted block of zero bits is to break the decryption. The former is not compressable, the latter is. 2. Assuming we solve this mystery of the universe and it turns out to be deterministic, we still have the problem of running the code on a computer that resides within the universe. If the universe is infinite, then it is possible because one Turing machine can simulate another. If the universe is finite (as quantum theory and the Big Bang suggest, also the lack of real Turing machines), then it is not possible because a state machine cannot simulate itself. Having the USB drive simulate all of the universe except itself would resolve this problem, but then if the USB drive resides outside the universe, how do we read the result? 3. Assuming we overcome this obstacle, it may be that the program will say how many fingers, but in that case the program also completely determines my behavior and might not allow me to answer. -- Matt Mahoney, [EMAIL PROTECTED] ----- Original Message ---- From: Eliezer S. Yudkowsky <[EMAIL PROTECTED]> To: [email protected] Sent: Friday, August 25, 2006 8:08:02 PM Subject: Re: [agi] Lossy *&* lossless compression Matt Mahoney wrote: > > DEL has a lossy model, and nothing compresses smaller. Is it smarter > than PKZip? > > Let me state one more time why a lossless model has more knowledge. > If x and x' have the same meaning to a lossy compressor (they > compress to identical codes), then the lossy model only knows > p(x)+p(x'). A lossless model also knows p(x) and p(x'). You can > argue that if x and x' are not distinguishable then this extra > knowledge is not important. But all text strings are distinguishable > to humans. Suppose I give you a USB drive that contains a lossless model of the entire universe excluding the USB drive - a bitwise copy of all quark positions and field strengths. (Because deep in your heart, you know that underneath the atoms, underneath the quarks, at the uttermost bottom of reality, are tiny little XML files...) Let's say that you've got the entire database, and a Python interpreter that can process it at any finite speed you care to specify. Now write a program that looks at those endless fields of numbers, and says how many fingers I'm holding up behind my back. Looks like you'll have to compress that data first. -- Eliezer S. Yudkowsky http://singinst.org/ Research Fellow, Singularity Institute for Artificial Intelligence ------- To unsubscribe, change your address, or temporarily deactivate your subscription, please go to http://v2.listbox.com/member/[EMAIL PROTECTED] ------- To unsubscribe, change your address, or temporarily deactivate your subscription, please go to http://v2.listbox.com/member/[EMAIL PROTECTED]
