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About this paper

Aapo Hyvarinen, Hiroshi Morioka

TCL trains features by labeling observations with their time-window indices and predicting those labels. Under assumptions on independent sources whose distributions change across windows, it can recover transformed sources after a nonlinear mixture, up to an invertible linear transformation. In simulations, TCL tracked transformed sources better than compared methods in nonlinear mixtures; this does not establish recovery of real-world sources.

Key insights

  • Many real-world time series exhibit natural nonstationarity, with statistical properties changing over time.
  • By explicitly modeling and leveraging temporal structure and training a network to discriminate between time segments, nonlinear source separation can become theoretically identifiable.
  • The features learned by Time-Contrastive Learning (TCL) are proven to be identifiable, representing nonlinear functions of the original independent sources up to a linear transformation.

Summary by alphaXiv.

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