FI-KAN: Fractal Interpolation Kolmogorov-Arnold Networks
This work addresses the limitations of traditional Kolmogorov–Arnold Networks (KANs), which rely on fixed-grid B-spline bases and struggle to approximate nonsmooth or multiscale functions effectively. The authors introduce, for the first time, fractal geometry into neural function approximation by proposing Pure FI-KAN and Hybrid FI-KAN architectures. These models employ learnable fractal interpolation function (FIF) bases constructed via iterated function systems (IFS) and incorporate a differentiable fractal dimension as an adaptive parameter to dynamically align the Hölder regularity of the basis functions with that of the target function. Empirical results demonstrate substantial improvements over conventional KANs: on Hölder continuity benchmarks, performance gains range from 1.3× to 33×; mean squared error on fractal targets is reduced by 6.3×; and accuracy in approximating solutions to nonsmooth partial differential equations improves by up to 79×.