9,358 research outputs found
Fast and Robust Rank Aggregation against Model Misspecification
In rank aggregation, preferences from different users are summarized into a
total order under the homogeneous data assumption. Thus, model misspecification
arises and rank aggregation methods take some noise models into account.
However, they all rely on certain noise model assumptions and cannot handle
agnostic noises in the real world. In this paper, we propose CoarsenRank, which
rectifies the underlying data distribution directly and aligns it to the
homogeneous data assumption without involving any noise model. To this end, we
define a neighborhood of the data distribution over which Bayesian inference of
CoarsenRank is performed, and therefore the resultant posterior enjoys
robustness against model misspecification. Further, we derive a tractable
closed-form solution for CoarsenRank making it computationally efficient.
Experiments on real-world datasets show that CoarsenRank is fast and robust,
achieving consistent improvement over baseline methods
A recommender system for process discovery
Over the last decade, several algorithms for process discovery and process conformance have been proposed. Still, it is well-accepted that there is no dominant algorithm in any of these two disciplines, and then it is often difficult to apply them successfully. Most of these algorithms need a close-to expert knowledge in order to be applied satisfactorily. In this paper, we present a recommender system that uses portfolio-based algorithm selection strategies to face the following problems: to find the best discovery algorithm for the data at hand, and to allow bridging the gap between general users and process mining algorithms. Experiments performed with the developed tool witness the usefulness of the approach for a variety of instances.Peer ReviewedPostprint (author’s final draft
A two-step fusion process for multi-criteria decision applied to natural hazards in mountains
Mountain river torrents and snow avalanches generate human and material
damages with dramatic consequences. Knowledge about natural phenomenona is
often lacking and expertise is required for decision and risk management
purposes using multi-disciplinary quantitative or qualitative approaches.
Expertise is considered as a decision process based on imperfect information
coming from more or less reliable and conflicting sources. A methodology mixing
the Analytic Hierarchy Process (AHP), a multi-criteria aid-decision method, and
information fusion using Belief Function Theory is described. Fuzzy Sets and
Possibilities theories allow to transform quantitative and qualitative criteria
into a common frame of discernment for decision in Dempster-Shafer Theory (DST
) and Dezert-Smarandache Theory (DSmT) contexts. Main issues consist in basic
belief assignments elicitation, conflict identification and management, fusion
rule choices, results validation but also in specific needs to make a
difference between importance and reliability and uncertainty in the fusion
process
Solving multiple-criteria R&D project selection problems with a data-driven evidential reasoning rule
In this paper, a likelihood based evidence acquisition approach is proposed
to acquire evidence from experts'assessments as recorded in historical
datasets. Then a data-driven evidential reasoning rule based model is
introduced to R&D project selection process by combining multiple pieces of
evidence with different weights and reliabilities. As a result, the total
belief degrees and the overall performance can be generated for ranking and
selecting projects. Finally, a case study on the R&D project selection for the
National Science Foundation of China is conducted to show the effectiveness of
the proposed model. The data-driven evidential reasoning rule based model for
project evaluation and selection (1) utilizes experimental data to represent
experts' assessments by using belief distributions over the set of final
funding outcomes, and through this historic statistics it helps experts and
applicants to understand the funding probability to a given assessment grade,
(2) implies the mapping relationships between the evaluation grades and the
final funding outcomes by using historical data, and (3) provides a way to make
fair decisions by taking experts' reliabilities into account. In the
data-driven evidential reasoning rule based model, experts play different roles
in accordance with their reliabilities which are determined by their previous
review track records, and the selection process is made interpretable and
fairer. The newly proposed model reduces the time-consuming panel review work
for both managers and experts, and significantly improves the efficiency and
quality of project selection process. Although the model is demonstrated for
project selection in the NSFC, it can be generalized to other funding agencies
or industries.Comment: 20 pages, forthcoming in International Journal of Project Management
(2019
GreedyDual-Join: Locality-Aware Buffer Management for Approximate Join Processing Over Data Streams
We investigate adaptive buffer management techniques for approximate evaluation of sliding window joins over multiple data streams. In many applications, data stream processing systems have limited memory or have to deal with very high speed data streams. In both cases, computing the exact results of joins between these streams may not be feasible, mainly because the buffers used to compute the joins contain much smaller number of tuples than the tuples contained in the sliding windows. Therefore, a stream buffer management policy is needed in that case. We show that the buffer replacement policy is an important determinant of the quality of the produced results. To that end, we propose GreedyDual-Join (GDJ) an adaptive and locality-aware buffering technique for managing these buffers. GDJ exploits the temporal correlations (at both long and short time scales), which we found to be prevalent in many real data streams. We note that our algorithm is readily applicable to multiple data streams and multiple joins and requires almost no additional system resources. We report results of an experimental study using both synthetic and real-world data sets. Our results demonstrate the superiority and flexibility of our approach when contrasted to other recently proposed techniques
Parameterized Algorithmics for Computational Social Choice: Nine Research Challenges
Computational Social Choice is an interdisciplinary research area involving
Economics, Political Science, and Social Science on the one side, and
Mathematics and Computer Science (including Artificial Intelligence and
Multiagent Systems) on the other side. Typical computational problems studied
in this field include the vulnerability of voting procedures against attacks,
or preference aggregation in multi-agent systems. Parameterized Algorithmics is
a subfield of Theoretical Computer Science seeking to exploit meaningful
problem-specific parameters in order to identify tractable special cases of in
general computationally hard problems. In this paper, we propose nine of our
favorite research challenges concerning the parameterized complexity of
problems appearing in this context
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