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112. Optimal Heterogeneous Collaborative Linear Regression and Contextual Bandits

Author

Huang, Xinmeng, Xu, Kan, Lee, Donghwan, Hassani, Hamed, Bastani, Hamsa, Dobriban, Edgar, Huang, Xinmeng, Xu, Kan, Lee, Donghwan, Hassani, Hamed, Bastani, Hamsa, and Dobriban, Edgar

Abstract

Large and complex datasets are often collected from several, possibly heterogeneous sources. Collaborative learning methods improve efficiency by leveraging commonalities across datasets while accounting for possible differences among them. Here we study collaborative linear regression and contextual bandits, where each instance's associated parameters are equal to a global parameter plus a sparse instance-specific term. We propose a novel two-stage estimator called MOLAR that leverages this structure by first constructing an entry-wise median of the instances' linear regression estimates, and then shrinking the instance-specific estimates towards the median. MOLAR improves the dependence of the estimation error on the data dimension, compared to independent least squares estimates. We then apply MOLAR to develop methods for sparsely heterogeneous collaborative contextual bandits, which lead to improved regret guarantees compared to independent bandit methods. We further show that our methods are minimax optimal by providing a number of lower bounds. Finally, we support the efficiency of our methods by performing experiments on both synthetic data and the PISA dataset on student educational outcomes from heterogeneous countries.

Published
2023

117. Mode-Conscious Stabilization of Switched Linear Control Systems against Adversarial Switchings

Author

Hu, Jianghai, Shen, Jinglai, and Lee, Donghwan

Abstract

The stabilization problem of a discrete-time switched linear control system using continuous control input against adversarial switchings is studied. This problem is formulated as a two-player dynamic game, and it is assumed that the continuous controller has access to the adversary’s switching mode at each time and can be of the form of an ensemble of mode-dependent state feedback controllers. Under this information structure, the (fastest) stabilizing rate is proposed as a quantitative metric of the system’s stabilizability. Conditions are derived on when the stabilizing rate can be exactly achieved by an admissible control policy and a counter example is given to show that the stabilizing rate may not always be attained by a mode-dependent linear state feedback control policy. Bounds of the stabilizing rate are derived using (semi)norms. When such bounds are tight, the corresponding extremal norms are characterized geometrically. Numerical algorithms based on ellipsoid and polytope norms are developed for computing bounds of the stabilizing rate and illustrated through examples.

Published
2023
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127. Q + -Algorithm: An Enhanced RFID Tag Collision Arbitration Algorithm

Author

Lee, Donghwan, Kim, Kyungkyu, Lee, Wonjun, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Doug, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Indulska, Jadwiga, editor, Ma, Jianhua, editor, Yang, Laurence T., editor, Ungerer, Theo, editor, and Cao, Jiannong, editor

Published
2007
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128. Genetic Algorithmic Topology Control for Two-Tiered Wireless Sensor Networks

Author

Lee, Donghwan, Lee, Wonjun, Kim, Joongheon, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Rangan, C. Pandu, editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Doug, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Shi, Yong, editor, van Albada, Geert Dick, editor, Dongarra, Jack, editor, and Sloot, Peter M. A., editor

Published
2007
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130. UbiComm: An Adaptive Vertical Handoff Decision Scheme for Heterogeneous Wireless Networks

Author

Lee, Wonjun, Kim, Eunkyo, Yu, Jieun, Lee, Donghwan, Choi, Jihoon, Kim, Joongheon, Shin, Christian K., Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Dough, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Youn, Hee Yong, editor, Kim, Minkoo, editor, and Morikawa, Hiroyuki, editor

Published
2006
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