#### Shubham Kumar Bharti

Shubham Kumar Bharti (Computer Science), advised by Jerry Zhu (Computer Science), and Kangwook Lee (Electrical and Computer Engineering), is interested in Reinforcement Learning, Fairness and Machine Teaching. His recent work focuses on fairness problems in sequential decision making. Currently, he is working on defenses against trojan attacks in Reinforcement Learning.

#### Jiaxin Hu

Jiaxin Hu (Statistics), advised by Miaoyan Wang (Statistics) and Jerry Zhu (Computer Science), works on statistical machine learning. Currently, she focuses on tensor/matrix data modeling and analysis with applications in neuroscience and social networks.

#### Max Hill

Max Hill (Mathematics), advised by Sebastien Roch (Mathematics) and Cecile Ane (Statistics), works in probability and mathematical phylogenetics. His recent work focuses on the impact of recombination in phylogenetic tree estimation.

#### Sijia Fang

Sijia Fang (Statistics), advised by Karl Rohe (Statistics) and Sebastian Roch (Mathematics), works on social network and spectral analysis. More specifically, she is interested in hierarchical structures in social networks. She is also interested in phylogenetic tree and network recovery problems.

#### Zhiyan Ding

Zhiyan Ding (Mathematics), advised by Qin Li (Mathematics), works on applied and computational mathematics. More specifically, he uses PDE analysis tools for analyzing machine learning algorithms, such as Bayesian sampling and over-parameterized neural networks. The PDE tools, including gradient flow equation, and mean-field analysis, are helpful in formulating the machine (deep) learning algorithms into certain mathematical descriptions that are easier to handle.

#### Yuchen Zeng

Yuchen Zeng (Computer Science), advised by Kangwook Lee (Electrical and Computer Engineering) and Stephen J. Wright (Computer Science), is interested in Trustworthy AI with a particular focus on fairness. Her recent work investigates training fair classifiers from decentralized data. Currently, she is working on developing a new fairness notion that considers dynamics.

#### Wisconsin Announces Fall ’21 and Spring ’22 RAs

The UW-Madison IFDS site is funding several Research Assistants during Fall 2021 and Spring 2022 to collaborate across disciplines on IFDS research. Each one is advised by a primary and a secondary adviser, all of them members of IFDS.

#### Jillian Fisher

Jillian Fisher (Statistics) works with Zaid Harchaoui (Statistics) and Yejin Choi (Allen School for CSE) on dataset biases and generative modeling. She is also interested in nonparametric and semiparametric statistical inference.

#### Yifang Chen

Yifang Chen (CSE) works is co-advised by Kevin Jamieson (CSE) and Simon Du (CSE). Yifang is an expert on algorithm design for active learning multi-armed bandits in the presence of adversarial corruptions. Recently she has been working with Kevin and Simon on sample efficient methods for multi-task learning.

#### Guanghao Ye

Guanghao Ye (CSE) works with Yin Tat Lee (CSE) and Dmitriy Drusvyatskiy (Mathematics) on designing faster algorithms for non-smooth non-convex optimization. He is interested in convex optimization. He developed the first nearly linear time algorithm for linear programs with small treewidth.

#### Josh Cutler

Josh Cutler (Mathematics) works with Dmitriy Drusvyatskiy (Mathematics) and Zaid Harchaoui (Statistics) on stochastic optimization for data science. His most recent work has focused on designing and analyzing algorithms for stochastic optimization problems with data distributions that evolve in time. Such problems appear routinely in machine learning and signal processing.

#### Romain Camilleri

Romain Camilleri (CSE) works with Kevin Jamieson (CSE), Maryam Fazel (ECE), and Lalit Jain (Foster School of Business). He is interested in robust high dimensional experimental design with adversarial arrivals. He also collaborates with IFDS student Zhihan Xiong (CSE).

#### Yue Sun

Yue Sun (ECE) works with Maryam Fazel (ECE) and Goiehran Mesbahi (Aeronautics), as well as collaborator Prof. Samet Oymak (UC Riverside). Yue is currently interested in two topics: (1) understanding the role of over-parametrization in meta-learning, and (2) gradient-based policy update methods for control, which connects the two fields of control theory and reinforcement learning.

#### Lang Liu

Lang Liu (Statistics) works with Zaid Harchaoui (Statistics) and Soumik Pal (Mathematics – Kantorovich Initiative) on statistical hypothesis testing and regularized optimal transport. He is also interested in statistical change detection and natural language processing.

#### Kristof Glauninger

Kristof Glauninger (Statistics) works with Zaid Harchaoui (Statistics), Virginia E. Armbrust (Oceanography) and François Ribalet (Oceanography) on statistical modeling for marine ecology. He focuses on statistical inference questions arising from phytoplankton population modeling. He is also interested in optimal transport and machine learning.

#### Alec Greaves-Tunnell

Alec Greaves-Tunnell (Statistics) works with Zaid Harchaoui (Statistics), Ali Shojaie (Biostatistics), and Azadeh Yazdan (Bioengineering) on distributionally robust learning for brain science and engineering. He is also interested in sequence models and time series in general, with applications to language processing and music analysis.

#### Adhyyan Narang

Adhyyan Narang (ECE) works with Maryam Fazel (ECE) and Lilian Ratliff (ECE). So far, he has worked to provide theoretical answers to foundational questions in learning from data: such as generalization of overparameterized models and robustness to adversarial examples. More recently, he is interested in providing guarantees for optimization in uncertain online environments in the presence of other agents.

#### Swati Padmanabhan

Swati Padmanabhan (ECE) works with Yin Tat Lee (Computer Science and Engineering) and Maryam Fazel (ECE) on designing a faster algorithm for the optimal design problem. She is also interested in semidefinite programming in general. She has developed several semidefinite programming in different settings which are fastest known in their setting.

#### Omid Sadeghi

Omid Sadeghi (ECE) works with Maryam Fazel as well as Lillian Ratliff (ECE). He is interested in the design and analysis of online optimization algorithms with budget constraints, and with stochastic or adversarial inputs. His work includes online resource allocation with submodular utility functions.

#### Zhihan Xiong

Zhihan Xiong (Computer Science and Engineering) works with Maryam Fazel (Electrical and Computer Engineering) and Kevin Jamieson (Computer Science and Engineering) as well as

Lalit Jain (Business School). His current work addresses optimal experimental design in a streaming setting where the measurement budget is limited and the quality of measurements vary unpredictably over time.

#### Changhun Jo

Changhun Jo (Mathematics), advised by Kangwook Lee (Electrical and Computer Engineering) and Sebastien Roch (Mathematics), is working on the theoretical understanding of machine learning. His recent work focuses on finding an optimal data poisoning algorithm against a fairness-aware learner. He also works on finding the fundamental limit on sample complexity of matrix completion in the presence of graph side information.

#### Lorenzo Najt

Lorenzo Najt (Mathematics), advised by Jordan Ellenberg (Math), investigates algorithmic and inferential questions related to ensemble analysis of gerrymandering. Related to this, he is interested in sampling connected graph partitions, and is working with Michael Newton (Statistics) to investigate applications to hypothesis testing with spatial data. He is also working on some questions about the fixed parameter tractability of polytope algorithms.

#### Yuetian Luo

Yuetian Luo is working with Anru Zhang (Statistics) and Yingyu Liang (Computer Science) on non-convex optimization problems involving low rank matrices and implicit regularization for non-convex optimization methods. We develop novel fast algorithms with provable faster convergence guarantees than common first order methods. The algorithm is based on a new sketching scheme we developed for high dimensional problems. Also we are interested in investigating implicit regularization for different non-convex optimization methods and different initialization schemes.

#### Yingda Li

Yingda Li (Mathematics) is working with Nan Chen (Mathematics) and Sebastien Roch (Mathematics) on uncertainty quantification and data assimilation. She aims to develop statistically accurate algorithms for solving high-dimensional nonlinear and non-Gaussian dynamical systems. She also works on predicting complex nonlinear turbulent dynamical systems with imperfect models and insufficient training data.

#### Mehmet Furkan Demirel

Mehmet Furkan Demirel (Computer Sciences), advised by Yingyu Liang (Computer Sciences) and Dimitris Papailiopoulos (Electrical and Computer Engineering), focuses on molecule property prediction and construction of proper representations of molecules for learning algorithms. He also works on representation learning for graph-structured data and graph neural networks.

#### Cora Allen-Savietta

Cora Allen-Savietta (Statistics) works with Cécile Ané (Statistics, Botany) and Sebastien Roch (Mathematics) to develop efficient methods to infer evolutionary history and identify ancient hybridizations. As the challenge of this work is to reconstruct ancestry using only modern data, she explores the identifiability of a network’s topology from sequence data only at the leaves. She is also expanding tree rearrangements and existing search strategies to explore the large and discrete space of semi-directed networks. Her work has applications to understanding the history of eukaryotes, viruses, languages, and more.

#### Shashank Rajput

Shashank Rajput (Computer Science), advised by Dimitris Papailiopoulos (Electrical and Computer Engineering), Kangwook Lee (Electrical and Computer Engineering) and Stephen Wright (Computer Science), works on problems in distributed machine learning and optimization. He works on developing techniques which are fast and scalable for practical use, and have theoretical guarantees. Currently, he is working on finding better shuffling mechanisms that beat random reshuffling as well as developing algorithms for training neural networks by only pruning them.

#### Shuqi Yu

Shuqi Yu (Mathematics), advised by Sebastien Roch (Mathematics) and working with Karl Rohe (Statistics) on large scale network models. She aims to establish theoretical guarantees for a new estimator of the number of communities in a stochastic blockmodel. She is also interested in phylogenetics questions, in particular, she works on the identifiability of the species phylogeny under an horizontal gene transfer model.