20,532 research outputs found
Quantifying Morphological Computation
The field of embodied intelligence emphasises the importance of the
morphology and environment with respect to the behaviour of a cognitive system.
The contribution of the morphology to the behaviour, commonly known as
morphological computation, is well-recognised in this community. We believe
that the field would benefit from a formalisation of this concept as we would
like to ask how much the morphology and the environment contribute to an
embodied agent's behaviour, or how an embodied agent can maximise the
exploitation of its morphology within its environment. In this work we derive
two concepts of measuring morphological computation, and we discuss their
relation to the Information Bottleneck Method. The first concepts asks how much
the world contributes to the overall behaviour and the second concept asks how
much the agent's action contributes to a behaviour. Various measures are
derived from the concepts and validated in two experiments which highlight
their strengths and weaknesses
Evaluating Morphological Computation in Muscle and DC-motor Driven Models of Human Hopping
In the context of embodied artificial intelligence, morphological computation
refers to processes which are conducted by the body (and environment) that
otherwise would have to be performed by the brain. Exploiting environmental and
morphological properties is an important feature of embodied systems. The main
reason is that it allows to significantly reduce the controller complexity. An
important aspect of morphological computation is that it cannot be assigned to
an embodied system per se, but that it is, as we show, behavior- and
state-dependent. In this work, we evaluate two different measures of
morphological computation that can be applied in robotic systems and in
computer simulations of biological movement. As an example, these measures were
evaluated on muscle and DC-motor driven hopping models. We show that a
state-dependent analysis of the hopping behaviors provides additional insights
that cannot be gained from the averaged measures alone. This work includes
algorithms and computer code for the measures.Comment: 10 pages, 4 figures, 1 table, 5 algorithm
Computing the Unique Information
Given a pair of predictor variables and a response variable, how much
information do the predictors have about the response, and how is this
information distributed between unique, redundant, and synergistic components?
Recent work has proposed to quantify the unique component of the decomposition
as the minimum value of the conditional mutual information over a constrained
set of information channels. We present an efficient iterative divergence
minimization algorithm to solve this optimization problem with convergence
guarantees and evaluate its performance against other techniques.Comment: To appear in 2018 IEEE International Symposium on Information Theory
(ISIT); 18 pages; 4 figures, 1 Table; Github link to source code:
https://github.com/infodeco/computeU
Quantifying galaxy morphology
How do the different shapes of galaxies arise? Milena Pawlik describes work to identify the role of galaxy mergers and starbursts in galactic evolution.Publisher PDFPeer reviewe
Bars in early- and late-type disks in COSMOS
We investigate the (large-scale) bar fraction in a mass-complete sample of M
> 10^10.5 Msun disk galaxies at 0.2 < z < 0.6 in the COSMOS field. The fraction
of barred disks strongly depends on mass, disk morphology, and specific star
formation rate (SSFR). At intermediate stellar mass (10^10.5 < M < 10^11 Msun)
the bar fraction in early-type disks is much higher, at all redshifts, by a
factor ~2, than that in late-type disks. This trend is reversed at higher
stellar mass (M > 10^11 Msun), where the fraction of bars in early-type disks
becomes significantly lower, at all redshifts, than that in late-type disks.
The bar fractions for galaxies with low and high SSFRs closely follow those of
the morphologically-selected early-type and late-type populations,
respectively. This indicates a close correspondence between morphology and SSFR
in disk galaxies at these earlier epochs. Interestingly, the total bar fraction
in 10^10.5 < M < 10^11 Msun disks is built up by a factor of ~2 over the
redshift interval explored, while for M > 10^11 Msun disks it remains roughly
constant. This indicates that, already by z ~ 0.6, spectral and morphological
transformations in the most massive disk galaxies have largely converged to the
familiar Hubble sequence that we observe in the local Universe, while for
intermediate mass disks this convergence is ongoing until at least z ~ 0.2.
Moreover, these results highlight the importance of employing mass-limited
samples for quantifying the evolution of barred galaxies. Finally, the
evolution of the barred galaxy populations investigated does not depend on the
large-scale environmental density (at least, on the scales which can be probed
with the available photometric redshifts).Comment: 10 pages, 4 figures, updated to reflect version accepted by MNRA
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