arXiv Machine Learning

Proofs of strong forms of the Bovdi--Geche universality conjecture and a complex analogue

The paper proves two universality theorems for single‑neuron neural networks. First, it establishes a strong form of the Bovdi–Geche universality conjecture for neurons over finite fields, employing a modified discrete logarithm activation function and the Weil bound on multiplicative character sums. Second, it generalises Aizenberg’s universality theorem to complex binary neurons with a weight vector independent of the target function, using an equidistribution theorem for dilates of maps into tori.

arXiv Machine Learning
Oct 16

Linear Independence of Polynomial Compositions with Bounded Input Degree

The paper proves the weak composition‑independence conjectures of Kohn, Marchetti, Massarenti and Mella by employing deformations of rational curves and a single kernel of the linearized equation, with Riemann‑Roch providing a contradiction from tangent fields with controlled poles. This result establishes that a neural network using a general polynomial activation function of sufficiently large degree is identifiable.

By Xiaotian Chang, Yacoub Hendi
arXiv Machine Learning
Aug 28

Linear Independence of Polynomial Compositions and Identifiability of Deep Neural Networks

The paper proposes a conjecture that composing a fixed number of distinct nonconstant polynomials with a generic high‑degree polynomial produces linearly independent polynomials, extending Newman–Slater’s theorem. The authors prove the conjecture for two polynomials and for any number when the degrees are bounded, and they show how these results explain the parameter symmetries of deep fully connected neural networks with generic polynomial activations. In particular, for architectures with layer‑specific activations of increasing degree, the conjecture’s proven cases fully characterize the parameter sets that yield the same end‑to‑end network function, and it also resolves the identifiability of shallow polynomial networks.

By Kathl\'en Kohn, Giovanni Luca Marchetti, Alex Massarenti, Massimiliano Mella
arXiv AI
Sep 10

Deep belief networks are exact

arXiv:2609.05572v1 Announce Type: new Abstract: We prove that every strictly positive probability distribution on \(\{-1,1\}^n\) is represented exactly by a sigmoid belief network with finite paramet...

By Gleb Smirnov
arXiv Machine Learning
Aug 31

What Neural Network Field Theory Can and Cannot Realise on a Computer

The paper investigates the limits of implementing neural network field theory on a computer, focusing on function classes that are regular enough for computation. It presents a no‑go theorem showing that finite‑width network ensembles cannot consistently realize either a quantum or effective field theory due to violations of reflection positivity and lack of scale separation. The study distinguishes between finite‑width and infinite‑width interpretations, concluding that only smeared correlators of the infinite‑width limit are computable with controlled error, and identifies two possible ways to evade the theorem—by relaxing finite variance or exact rotation invariance.

By Thomas R. Harvey
arXiv Machine Learning
Oct 12

Constructive Bounds for the Topological Expressivity of Neural Networks

The paper investigates topological expressivity of neural networks by examining Betti numbers of the network output rather than decision boundaries. It proves that a ReLU network with a specific architecture can represent spaces homotopy equivalent to wedge sums of spheres with arbitrary Betti numbers, and provides tighter bounds for spaces equivalent to products of spheres. The authors also conjecture an even stronger bound for networks representing a single sphere.

By Kosio Beshkov