All elementary functions from a single binary operator

(arxiv.org)

98 points | by pizza 3 hours ago ago

38 comments

  • DoctorOetker 17 minutes ago

    I'm still reading this, but if this checks out, this is one of the most significant discoveries in years.

    Why use splines or polynomials or haphazardly chosen basis functions if you can just fit (gradient descent) your data or wave functions to the proper computational EML tree?

    Got a multidimensional and multivariate function to model (with random samples or a full map)? Just do gradient descent and convert it to approximant EML trees.

    Perform gradient descent on EML function tree "phi" so that the derivatives in the Schroedinger equation match.

    But as I said, still reading, this sounds too good to be true, but I have witnessed such things before :)

    • gilgoomesh 5 minutes ago

      > Why use splines or polynomials or haphazardly chosen basis functions if you can just fit (gradient descent) your data or wave functions to the proper computational EML tree?

      Same reason all boolean logic isn't performed with combinations of NAND – it's computationally inefficient. Polynomials are (for their expressivity) very quick to compute.

  • lioeters 17 minutes ago

    > A calculator with just two buttons, EML and the digit 1, can compute everything a full scientific calculator does

    Reminds me of the Iota combinator, one of the smallest formal systems that can be combined to produce a universal Turing machine, meaning it can express all of computation.

  • entaloneralie 30 minutes ago

    This is amazing! I love seeing FRACTRAN-shaped things on the homepage :) This reminds me of how 1-bit stacks are encoded in binary:

    A stack of zeros and ones can be encoded in a single number by keeping with bit-shifting and incrementing.

        Pushing a 0 onto the stack is equivalent to doubling the number.
        Pushing a 1 is equivalent to doubling and adding 1.
        Popping is equivalent to dividing by 2, where the remainder is the number.
    
    I use something not too far off for my daily a programming based on a similar idea:

    Rejoice is a concatenative programming language in which data is encoded as multisets that compose by multiplication. Think Fractran, without the rule-searching, or Forth without a stack.

    https://wiki.xxiivv.com/site/rejoice

  • krick 26 minutes ago

    > using EML trees as trainable circuits ..., I demonstrate the feasibility of exact recovery of closed-form elementary functions from numerical data at shallow tree depths up to 4

    That's awesome. I always wondered if there is some way to do this.

  • qiller 33 minutes ago

    For completeness, there is also Peirce’s arrow aka NOR operation which is functionally complete. Fun applications iirc VMProtect copy protection system has an internal VM based on NOR.

    Quick google seach brings up https://github.com/pr701/nor_vm_core, which has a basic idea

  • simplesighman an hour ago

    > For example, exp(x)=eml(x,1), ln(x)=eml(1,eml(eml(1,x),1)), and likewise for all other operations

    I read the paper. Is there a table covering all other math operations translated to eml(x,y) form?

    • sandrocksand 16 minutes ago

      I think what you want is the supplementary information, part II "completeness proof sketch" on page 12. You already spotted the formulas for "exp" and real natural "L"og; then x - y = eml(L(x), exp(y)) and from there apparently it is all "standard" identities. They list the arithmetic operators then some constants, the square root, and exponentials, then the trig stuff is on the next page.

      You can find this link on the right side of the arxiv page:

      https://arxiv.org/src/2603.21852v2/anc/SupplementaryInformat...

    • saratogacx 30 minutes ago

      last page of the PDF has several tree's that represent a few common math functions.

    • jmyeet 25 minutes ago

      I was curious about that too. Gemini actually gave a decent list. Trig functions come from Euler's identity:

          e^ix = cos x + i sin x
      
      which means:

          e^-ix = cos -x + i sin -x
                = cos x - i sin x
      
      so adding them together:

         e^ix + e^-ix = 2 cos x
         cos x = (e*ix - e^-ix) / 2
      
      So I guess the real part of that.

      Multiplication, division, addition and subtraction are all straightforward. So are hyperbolic trig functions. All other trig functions can be derived as per above.

  • tripdout an hour ago

    Interesting, but is the required combination of EML gates less complex than using other primitives?

  • nonfamous an hour ago

    How would an architecture with a highly-optimized hardware implementation of EML compare with a traditional math coprocessor?

    • wildzzz an hour ago

      Dreadfully slow for integer math but probably some similar performance to something like a CORDIC for specific operations. If you can build an FPU that does exp() and ln() really fast, it's simple binary tree traversal to find the solution.

      • AlotOfReading 29 minutes ago

        You already have an FPU that approximates exp() and ln() really fast, because float<->integer conversions approximate the power 2 functions respectively. Doing it accurately runs face-first into the tablemaker's dilemma, but you could do this with just 2 conversions, 2 FMAs (for power adjustments), and a subtraction per. A lot of cases would be even faster. Whether that's worth it will be situational.

  • jekude an hour ago

    What would physical EML gates be implemented in reality?

    Posts like these are the reason i check HN every day

  • peterlk an hour ago

    Reminds me a bit of the coolest talk I ever got to see in person: https://youtu.be/FITJMJjASUs?si=Fx4hmo77A62zHqzy

    It’s a derivation of the Y combinator from ruby lambdas

    • Analemma_ an hour ago

      If you've never worked through a derivation/explanation of the Y combinator, definitely find one (there are many across the internet) and work through it until the light bulb goes off. It's pretty incredible, it almost seems like "matter ex nihilo" which shouldn't work, and yet does.

      It's one of those facts that tends to blow minds when it's first encountered, I can see why one would name a company after it.

    • thaumasiotes an hour ago

      Have you gone through The Little Schemer?

      More on topic:

      > No comparable primitive has been known for continuous mathematics: computing elementary functions such as sin, cos, sqrt, and log has always required multiple distinct operations.

      I was taught that these were all hypergeometric functions. What distinction is being drawn here?

  • noobermin 16 minutes ago

    I don't mean to shit on their interesting result, but exp or ln are not really that elementary themselves... it's still an interesting result, but there's a reason that all approximations are done using series of polynomials (taylor expansion).

  • hyperhello an hour ago

    > eml(x,y)=exp(x)-ln(y)

    Exp and ln, isn't the operation its own inverse depending on the parameter? What a neat find.

    • thaumasiotes 27 minutes ago

      > isn't the operation its own inverse depending on the parameter?

      This is a function from ℝ² to ℝ. It can't be its own inverse; what would that mean?

      • hyperhello 6 minutes ago

        eml(1,eml(x,1)) = eml(eml(1,x),1) = exp(ln(x)) = ln(exp(x)) = x

  • supermdguy an hour ago

    Next step is to build an analog scientific calculator with only EML gates

  • selcuka an hour ago

    So, like brainf*ck (the esoteric programming language), but for maths?

  • zephen an hour ago

    Judging by the title, I thought I would have a good laugh, like when the doctor discovered numerical integration and published a paper.

    But no...

    This is about continuous math, not ones and zeroes. Assuming peer review proves it out, this is outstanding.

    • paulpauper 11 minutes ago

      I don't think this is ever making it past the editor of any journal, let alone peer review.

      Elementary functions such as exponentiation, logarithms and trigonometric functions are the standard vocabulary of STEM education. Each comes with its own rules and a dedicated button on a scientific calculator;

      What?

      and No comparable primitive has been known for continuous mathematics: computing elementary functions such as sin, cos, √ , and log has always required multiple distinct operations. Here we show that a single binary operator

      Yeah, this is done by using tables and series. His method does not actually facilitate the computation of these functions.

      There is no such things as "continuous mathematics". Maybe he meant to say continuous function?

      Looking at page 14, it looks like he reinvented the concept of the vector valued function or something. The whole thing is rediscovering something that already exists.

  • BobbyTables2 2 hours ago

    How does one actually add with this?

    • curtisf 2 minutes ago

      It's basically using the "-" embedded in the definition of the eml operator.

      Table 4 shows the "size" of the operators when fully expanded to "eml" applications, which is quite large for +, -, ×, and /.

      Here's one approach which agrees with the minimum sizes they present:

              eml(x, y             ) = exp(x) − ln(y) # 1 + x + y
              eml(x, 1             ) = exp(x)         # 2 + x
              eml(1, y             ) = e - ln(y)      # 2 + y
              eml(1, exp(e - ln(y))) = ln(y)          # 6 + y; from pdf(5)
                               ln(1) = 0              # 7
      
      After you have ln and exp, you can invert their applications in the eml function

                    eml(ln x, exp y) = x - y          # 9 + x + y
      
      Using a subtraction-of-subtraction to get addition leads to the cost of "27" in Table 4; I'm not sure what formula leads to 19 but I'm guessing it avoids the expensive construction of 0 by using something simpler that cancels:

                         x - (0 - y) = x + y          # 25 + {x} + {y}
    • bzax 2 hours ago

      Well, once you've derived unary exp and ln you can get subtraction, which then gets you unary negation and you have addition.

    • nick238 44 minutes ago

      Don't know adding, but multiplication has diagram on the last page of the PDF.

      xy = eml(eml(1, eml(eml(eml(eml(1, eml(eml(1, eml(1, x)), 1)), eml(1, eml(eml(1, eml(y, 1)), 1))), 1), 1)), 1)

      From Table 4, I think addition is slightly more complicated?

      • simplesighman 6 minutes ago

        Thanks for posting that. You had a transcribing typo which was corrected in the ECMAScript below. Here's the calculation for 5 x 7:

            const eml = (x,y) => Math.exp(x) - Math.log(y);
            const mul = (x,y) => eml(eml(1,eml(eml(eml(1,eml(eml(1,eml(1,x)),1)),eml(1,eml(eml(1,eml(y,1)),1))),1)),1);
            console.log(mul(5,7));
        
        > 35.00000000000001
      • Charon77 18 minutes ago

        x+y = ln(exp(x) * exp(y))

        exp(a) = eml(a, 1) ln(a)=eml(1,eml(eml(1,a),1))

        Plugging those in is an excercise to the reader

        • jcgrillo 3 minutes ago

          might need to turn the paper sideways