Integer multiplication below n log n

(github.com)

27 points | by E-Reverance 1 hour ago

5 comments

  • wk_end 4 minutes ago
    Is there an associated machine-checked proof of this?

    We're in full vibe-code mode at work, so I understand both how powerful frontier models can be and how often they can over-confidentially state subtly (or not so subtly) wrong things, even when you're taking great efforts to try to keep that from happening.

    So without a Lean development or extensive human verification, I guess I'm a little bit skeptical, and even sort of hoping this is wrong - not just because of my not so positive feelings about AI, but by my disposition towards beauty in math. n log n is an awful lot nicer than what we have here.

  • shmoil 25 minutes ago
    I laughed out loud at the n lg n ^ (1 - 2^{-182}). It is so funny.
    • dprkh 0 minutes ago
      Why is that funny?
    • elcritch 13 minutes ago
      Wowzers!

      This also reaffirms my (wishful) thinking that if there’s a way to do FTL communication it’ll be something with an absurdly tiny factor like 2^-182 with a slight asymmetry in a probability somewhere.

      Then you’re not violating FTL, just gaining a very slight chance that you might know something FTL – probably.

      • hgoel 7 minutes ago
        Given that c is the speed of causality itself, FTL communications would effectively be like predicting the future.

        From that angle, beating light speed by some absurdly tiny factor would probably correspond to a means of predicting the future at some almost absurdly tiny factor better than random guessing. Depending on how predictable the thing being communicated with is and how far away it is,

    • qarl 21 minutes ago
      Dangit! I was betting on -183.
      • utopcell 6 minutes ago
        You didn't believe!
  • 12390asdjkas 13 minutes ago
    this is perfect for when i have an array of at LEAST 2^118000 items

    i will NEVER care about proposed multiplication speedups unless they are truly generalized

    • zamadatix 4 minutes ago
      If you view them as "theories of computational limits" instead of "proposed practical speedups" they can be a lot more interesting.

      It's most interesting when the lower bound can actually be proven. In lack of that, we have to guess what the best possible algorithm might yield (generalized or not). This tells us that need not be O(n log n) and we have the opportunity to still find better algorithms than we typically thought would be possible. This does the latter, which is interesting, but it just leaves us to hunger more for what the real limit must be :).

  • MinimalAction 21 minutes ago
    For the uninitiated, why is this interesting given it doesn't seem to be so much below the threshold?
    • Chinjut 16 minutes ago
      It's interesting because people wondered if it was possible to go below the threshold at all, that's all. Many suspected it was not possible.
  • infocollector 37 minutes ago
    This is pretty remarkable, IF someone can understand it :)
    • saagarjha 29 minutes ago
      I only skimmed the paper but it doesn’t see particularly dense, mostly just relying on college math?
      • cr4zy 21 minutes ago
        It's 50 pages and cites this other paper in the same repo:

        OpenAI. An explicit power saving for the exact discrete Fourier transform.

        Here's a random excerpt:

        8.3 The middle transform and the final permutation The factor QFt in (35) can be computed from a cyclic convolution and two pointwise phase multiplications. The chirp identity below performs the frequency change in Q without applying Q as a separate permutation of the array. The second identity shows how the retained source permutation R cancels when computing a convolution. Here ∗ denotes cyclic convolution on the product of the coordinate groups and a dot denotes coordinatewise multiplication.