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Kolmogorov–Arnold network

nounAlso: KAN, KANs

In plain wordsA 2024 alternative to the standard neural network: instead of fixed rules inside neurons, every connection learns its own small curve, which can make the result easier to read as a formula.

  1. A neural networkneural network, n.: A kind of computer program that learns a task from examples by tuning thousands to billions of connections between simple number-crunching units, an arrangement loosely inspired by nerve cells in the brain. architecture inspired by the Kolmogorov–Arnold representation theorem, which states that any continuous function of several variables on a closed, bounded domain (such as the unit cube) can be written using only addition and compositions of continuous functions of one variable. Its learnable parts sit in a different place from a multilayer perceptronmultilayer perceptron, n.: A neural network made of several layers of artificial neurons, each connected to every neuron in the next layer. It is the simplest kind of deep network and a component of almost every modern model.'s: instead of learned linear weights on the connections and a fixed activation functionactivation function, n.: The simple rule each artificial neuron applies to its total input to decide its output, such as 'keep positive values, turn negatives into zero'. Without it, a deep network would be no smarter than a single layer. at each unit, every connection applies its own learned one-variable function, usually a B-spline plus a simple base function, and each unit just adds up what arrives. Its authors reported that small KANs could match much larger MLPs on function fitting and on solving partial differential equations, with better scaling in these settings, and that trained KANs can be pruned and converted into symbolic formulas, aiding scientific discovery. Follow-up studies found that at matched parameters or compute KANs mostly trail MLPs outside symbolic and low-dimensional scientific tasks, and spline evaluation makes them slow on GPUs; their value remains debated.

    After pruning, the KAN's learned edge functions matched a sine and a square almost exactly.

Origin

Introduced by Ziming Liu, Yixuan Wang, Sachin Vaidya, Fabian Ruehle, James Halverson, Marin Soljačić, Thomas Hou and Max Tegmark in 'KAN: Kolmogorov–Arnold Networks' (arXiv, April 2024), which drew wide attention; 'KAN 2.0' followed in August 2024. The underlying theorem was proved by Andrey Kolmogorov and Vladimir Arnold in 1956–57, resolving a version of Hilbert's thirteenth problem.

Related

See also
  • multilayer perceptronmultilayer perceptron, n.: A neural network made of several layers of artificial neurons, each connected to every neuron in the next layer. It is the simplest kind of deep network and a component of almost every modern model.
  • universal approximation theoremuniversal approximation theorem, n.: A mathematical result showing that a neural network with enough neurons can imitate essentially any smooth input-to-output relationship as closely as you like, though it does not say how to find that network.
  • activation functionactivation function, n.: The simple rule each artificial neuron applies to its total input to decide its output, such as 'keep positive values, turn negatives into zero'. Without it, a deep network would be no smarter than a single layer.
  • interpretable modelinterpretable model, n.: A model simple or structured enough that a person can follow exactly how it turns inputs into a decision — like a short checklist or a points-based score — with no separate explanation tool needed.
Contrast with
  • multilayer perceptronmultilayer perceptron, n.: A neural network made of several layers of artificial neurons, each connected to every neuron in the next layer. It is the simplest kind of deep network and a component of almost every modern model.

Sources

  1. Liu, Z. et al. (2024). KAN: Kolmogorov–Arnold Networks. arXiv:2404.19756. arxiv.org/abs/2404.19756

Mentioned in

Max TegmarkMax Tegmark, prop. n.: A Swedish-American physicist at MIT who co-founded the Future of Life Institute, which organized the 2023 open letter calling for a pause in training the most powerful AI systems., multilayer perceptronmultilayer perceptron, n.: A neural network made of several layers of artificial neurons, each connected to every neuron in the next layer. It is the simplest kind of deep network and a component of almost every modern model., universal approximation theoremuniversal approximation theorem, n.: A mathematical result showing that a neural network with enough neurons can imitate essentially any smooth input-to-output relationship as closely as you like, though it does not say how to find that network.