# Computational Information Geometry For Binary Classification of High-Dimensional Random Tensors

How to cite:
Pham, G..; Boyer, R..; Nielsen, F. Computational Information Geometry For Binary Classification of High-Dimensional Random Tensors. *Preprints* **2018**, 2018020008 (doi: 10.20944/preprints201802.0008.v1).
Pham, G..; Boyer, R..; Nielsen, F. Computational Information Geometry For Binary Classification of High-Dimensional Random Tensors. Preprints 2018, 2018020008 (doi: 10.20944/preprints201802.0008.v1).

## Abstract

high-dimensional random tensor is a fundamental under-studied difficult problem. In this work, we

consider two Signal to Noise Ratio (SNR)-based detection problems of interest. Under the alternative

hypothesis, i.e., for a non-zero SNR, the observed signals are either a noisy rank-R tensor admitting a

Q-order Canonical Polyadic Decomposition (CPD) with large factors of size Nq R, i.e, for 1 q Q,

where R, Nq ! ¥ with R1/q/Nq converge towards a finite constant or a noisy tensor admitting

TucKer Decomposition (TKD) of multilinear (M1, . . . ,MQ)-rank with large factors of size Nq Mq,

i.e, for 1 q Q, where Nq,Mq ! ¥ with Mq/Nq converge towards a finite constant. The detection

of the random entries (coefficients) of the core tensor in the CPD/TKD is hard to study since the

exact derivation of the error probability is mathematically intractable. To circumvent this technical

difficulty, the Chernoff Upper Bound (CUB) for larger SNR and the Fisher information at low SNR

are derived and studied, based on information geometry theory. The tightest CUB is reached for

the value minimizing the error exponent, denoted by s?. In general, due to the asymmetry of the

s-divergence, the Bhattacharyya Upper Bound (BUB) (that is, the Chernoff Information calculated at

s? = 1/2) can not solve this problem effectively. As a consequence, we rely on a costly numerical

optimization strategy to find s?. However, thanks to powerful random matrix theory tools, a simple

analytical expression of s? is provided with respect to the Signal to Noise Ratio (SNR) in the two

schemes considered. A main conclusion of this work is that the BUB is the tightest bound at low

SNRs. This property is, however, no longer true for higher SNRs.

## Subject Areas

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