356 research outputs found
Primal-Dual Rates and Certificates
We propose an algorithm-independent framework to equip existing optimization
methods with primal-dual certificates. Such certificates and corresponding rate
of convergence guarantees are important for practitioners to diagnose progress,
in particular in machine learning applications. We obtain new primal-dual
convergence rates, e.g., for the Lasso as well as many L1, Elastic Net, group
Lasso and TV-regularized problems. The theory applies to any norm-regularized
generalized linear model. Our approach provides efficiently computable duality
gaps which are globally defined, without modifying the original problems in the
region of interest.Comment: appearing at ICML 2016 - Proceedings of the 33rd International
Conference on Machine Learning, New York, NY, USA, 2016. JMLR: W&CP volume 4
Scalable and interpretable product recommendations via overlapping co-clustering
We consider the problem of generating interpretable recommendations by
identifying overlapping co-clusters of clients and products, based only on
positive or implicit feedback. Our approach is applicable on very large
datasets because it exhibits almost linear complexity in the input examples and
the number of co-clusters. We show, both on real industrial data and on
publicly available datasets, that the recommendation accuracy of our algorithm
is competitive to that of state-of-art matrix factorization techniques. In
addition, our technique has the advantage of offering recommendations that are
textually and visually interpretable. Finally, we examine how to implement our
technique efficiently on Graphical Processing Units (GPUs).Comment: In IEEE International Conference on Data Engineering (ICDE) 201
Performative Prediction: Past and Future
Predictions in the social world generally influence the target of prediction,
a phenomenon known as performativity. Self-fulfilling and self-negating
predictions are examples of performativity. Of fundamental importance to
economics, finance, and the social sciences, the notion has been absent from
the development of machine learning. In machine learning applications,
performativity often surfaces as distribution shift. A predictive model
deployed on a digital platform, for example, influences consumption and thereby
changes the data-generating distribution. We survey the recently founded area
of performative prediction that provides a definition and conceptual framework
to study performativity in machine learning. A consequence of performative
prediction is a natural equilibrium notion that gives rise to new optimization
challenges. Another consequence is a distinction between learning and steering,
two mechanisms at play in performative prediction. The notion of steering is in
turn intimately related to questions of power in digital markets. We review the
notion of performative power that gives an answer to the question how much a
platform can steer participants through its predictions. We end on a discussion
of future directions, such as the role that performativity plays in contesting
algorithmic systems
Redshift-space limits of bound structures
An exponentially expanding Universe, possibly governed by a cosmological
constant, forces gravitationally bound structures to become more and more
isolated, eventually becoming causally disconnected from each other and forming
so-called "island universes". This new scenario reformulates the question about
which will be the largest structures that will remain gravitationally bound,
together with requiring a systematic tool that can be used to recognize the
limits and mass of these structures from observational data, namely redshift
surveys of galaxies. Here we present a method, based on the spherical collapse
model and N-body simulations, by which we can estimate the limits of bound
structures as observed in redshift space. The method is based on a theoretical
criterion presented in a previous paper that determines the mean density
contrast that a spherical shell must have in order to be marginally bound to
the massive structure within it. Understanding the kinematics of the system, we
translated the real-space limiting conditions of this "critical" shell to
redshift space, producing a projected velocity envelope that only depends on
the density profile of the structure. From it we created a redshift-space
version of the density contrast that we called "density estimator", which can
be calibrated from N-body simulations for a reasonable projected velocity
envelope template, and used to estimate the limits and mass of a structure only
from its redshift-space coordinates.Comment: Contains 12 pages, 12 figures and 8 table
- …