6,703 research outputs found
FeDXL: Provable Federated Learning for Deep X-Risk Optimization
In this paper, we tackle a novel federated learning (FL) problem for
optimizing a family of X-risks, to which no existing FL algorithms are
applicable. In particular, the objective has the form of , where two sets of data
are distributed over multiple machines, is a pairwise loss that
only depends on the prediction outputs of the input data pairs , and
is possibly a non-linear non-convex function. This problem has
important applications in machine learning, e.g., AUROC maximization with a
pairwise loss, and partial AUROC maximization with a compositional loss. The
challenges for designing an FL algorithm lie in the non-decomposability of the
objective over multiple machines and the interdependency between different
machines. To address the challenges, we propose an active-passive decomposition
framework that decouples the gradient's components with two types, namely
active parts and passive parts, where the active parts depend on local data
that are computed with the local model and the passive parts depend on other
machines that are communicated/computed based on historical models and samples.
Under this framework, we develop two provable FL algorithms (FeDXL) for
handling linear and nonlinear , respectively, based on federated averaging
and merging. We develop a novel theoretical analysis to combat the latency of
the passive parts and the interdependency between the local model parameters
and the involved data for computing local gradient estimators. We establish
both iteration and communication complexities and show that using the
historical samples and models for computing the passive parts do not degrade
the complexities. We conduct empirical studies of FeDXL for deep AUROC and
partial AUROC maximization, and demonstrate their performance compared with
several baselines
Distribution specificities of long-period comets' perihelia. Hypothesis of the large planetary body on the periphery of the Solar System
The present paper reviews selected aspects of the Guliyev's hypothesis about
the massive celestial body at a distance of 250-400 AU from the Sun as well as
the factor of comets transfer. It is shown, that the conjecture of the point
around which cometary perihelia might be concentrated, is not consistent. On
the issue of perihelia distribution, priority should be given to the assumption
that there is a plane or planes around which the concentration takes place. A
total of 24 comet groups were investigated. In almost all cases there are
detected two types of planes or zones: the first one is very close to the
ecliptic, another one is about perpendicular to it and has the parameters: ip =
86{\deg}, {\Omega}p = 271.7{\deg}. The existence of the first area appears to
be related to the influence of giant planets. The Guliyev's hypothesis says
that there is a massive perturber in the second zone, at a distance of 250-400
AU. It shows that number of aphelia and distant nodes of cometary orbits in
this interval significantly exceeds the expected background. Analysis of the
angular parameters of the comets, calculated relative to the second plane
(reference point is the ascending node of a large circle) displays clear
patterns: shortage of comets near i' = 180{\deg}, excess of them near B'=
0{\deg} (ecliptic latitude of perihelion) and shortage near B'=-90{\deg}. The
analysis also shows irregularity of distant nodes, overpopulation of perihelion
longitudes in the range 350{\deg}-20{\deg}. Plotted distributions of aphelia
N(Q) and distant cometary nodes clearly indicate a perturbation of the natural
course near 300 AU. On the basis of collected cometary data, we have estimated
orbital elements of the hypothetical planetary body: a = 337 AU; e = 0.14;
{\omega} = 57{\deg}; {\Omega} = 272.7{\deg}; i = 86{\deg}
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