Learning Partially Observed Linear Dynamical Systems from Logarithmic
Number of Samples
- URL: http://arxiv.org/abs/2010.04015v1
- Date: Thu, 8 Oct 2020 14:23:48 GMT
- Title: Learning Partially Observed Linear Dynamical Systems from Logarithmic
Number of Samples
- Authors: Salar Fattahi
- Abstract summary: We study the problem of learning partially observed linear dynamical systems from a single sample trajectory.
Our result significantly improves the sample complexity of learning partially observed linear dynamical systems.
- Score: 4.7464518249313805
- License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
- Abstract: In this work, we study the problem of learning partially observed linear
dynamical systems from a single sample trajectory. A major practical challenge
in the existing system identification methods is the undesirable dependency of
their required sample size on the system dimension: roughly speaking, they
presume and rely on sample sizes that scale linearly with respect to the system
dimension. Evidently, in high-dimensional regime where the system dimension is
large, it may be costly, if not impossible, to collect as many samples from the
unknown system. In this paper, we will remedy this undesirable dependency on
the system dimension by introducing an $\ell_1$-regularized estimation method
that can accurately estimate the Markov parameters of the system, provided that
the number of samples scale logarithmically with the system dimension. Our
result significantly improves the sample complexity of learning partially
observed linear dynamical systems: it shows that the Markov parameters of the
system can be learned in the high-dimensional setting, where the number of
samples is significantly smaller than the system dimension. Traditionally, the
$\ell_1$-regularized estimators have been used to promote sparsity in the
estimated parameters. By resorting to the notion of "weak sparsity", we show
that, irrespective of the true sparsity of the system, a similar regularized
estimator can be used to reduce the sample complexity of learning partially
observed linear systems, provided that the true system is inherently stable.
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