3 research outputs found
Nonlinear System Identification via Tensor Completion
Function approximation from input and output data pairs constitutes a
fundamental problem in supervised learning. Deep neural networks are currently
the most popular method for learning to mimic the input-output relationship of
a general nonlinear system, as they have proven to be very effective in
approximating complex highly nonlinear functions. In this work, we show that
identifying a general nonlinear function from
input-output examples can be formulated as a tensor completion problem and
under certain conditions provably correct nonlinear system identification is
possible. Specifically, we model the interactions between the input
variables and the scalar output of a system by a single -way tensor, and
setup a weighted low-rank tensor completion problem with smoothness
regularization which we tackle using a block coordinate descent algorithm. We
extend our method to the multi-output setting and the case of partially
observed data, which cannot be readily handled by neural networks. Finally, we
demonstrate the effectiveness of the approach using several regression tasks
including some standard benchmarks and a challenging student grade prediction
task.Comment: AAAI 202
Revisiting Nonlocal Self-Similarity from Continuous Representation
Nonlocal self-similarity (NSS) is an important prior that has been
successfully applied in multi-dimensional data processing tasks, e.g., image
and video recovery. However, existing NSS-based methods are solely suitable for
meshgrid data such as images and videos, but are not suitable for emerging
off-meshgrid data, e.g., point cloud and climate data. In this work, we revisit
the NSS from the continuous representation perspective and propose a novel
Continuous Representation-based NonLocal method (termed as CRNL), which has two
innovative features as compared with classical nonlocal methods. First, based
on the continuous representation, our CRNL unifies the measure of
self-similarity for on-meshgrid and off-meshgrid data and thus is naturally
suitable for both of them. Second, the nonlocal continuous groups can be more
compactly and efficiently represented by the coupled low-rank function
factorization, which simultaneously exploits the similarity within each group
and across different groups, while classical nonlocal methods neglect the
similarity across groups. This elaborately designed coupled mechanism allows
our method to enjoy favorable performance over conventional NSS methods in
terms of both effectiveness and efficiency. Extensive multi-dimensional data
processing experiments on-meshgrid (e.g., image inpainting and image denoising)
and off-meshgrid (e.g., climate data prediction and point cloud recovery)
validate the versatility, effectiveness, and efficiency of our CRNL as compared
with state-of-the-art methods