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ZENODO
Report . 2026
License: CC BY
Data sources: ZENODO
ZENODO
Report . 2026
License: CC BY
Data sources: Datacite
ZENODO
Report . 2026
License: CC BY
Data sources: Datacite
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Disentangling Collapse, Positional Structure, and Representation Richness in SIGReg-Regularised Time-Series Representations

Authors: Patil, Rishabh Ashok;

Disentangling Collapse, Positional Structure, and Representation Richness in SIGReg-Regularised Time-Series Representations

Abstract

LeJEPA replaces the heuristic machinery of modern self-supervised learning (asymmetric encoders, stop-gradients, momentum teachers, schedulers) with a single isotropic-Gaussian regulariser, SIGReg. Carrying SIGReg to sequence models exposes a documented hazard: a naive pooled application can drive every sequence to a constant vector along time, a time-axis collapse the objective fails to penalise. We build a heuristics-free time-series representation-learning library and compare three placements of SIGReg relative to the time axis (pooled, dual, structured). The collapse is real and placement-controlled: dual raises across-time variance by roughly an order of magnitude. Our central result is negative and clarifying: through a factorial crossing encoder architecture with placement and probe feature, the across-time variance collapse does not measure downstream order availability and is anticorrelated with it (Spearman rho = -0.64). What determines temporal-order retention is the encoder's positional structure, an axis orthogonal to the placement that controls the collapse: a position-free encoder gives a permutation-invariant pooled feature at exactly chance (0.500) on a content-matched probe over two datasets, while a positional transformer recovers order at 0.97-1.00 even when maximally collapsed. The dual placement is nonetheless valuable where the task needs the richer representation it produces: on UCI HAR it beats pooled by 8-11 accuracy points, and an eight-seed paired-significance forecasting study finds it significantly better on ETTh2 and ETTm1, worse on PEMS08, and indistinguishable on ETTh1. We propose a two-axis account: preventing the collapse does not change order availability (set by positional structure) but increases representation richness (effective rank), which helps tasks whose targets are structured rather than near-constant.

Keywords

positional encoding, effective rank, self supervised learning, SIGReg, dimensional collapse, time-series representation learning, LeJEPA, transformers, joint-embedding predictive architectures, isotropic-Gaussian regularisation

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selected citations
These citations are derived from selected sources.
This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Citations provided by BIP!
popularity
This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network.
BIP!Popularity provided by BIP!
influence
This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Influence provided by BIP!
impulse
This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network.
BIP!Impulse provided by BIP!
0
Average
Average
Average