(Georgia Institute of Technology, 2019-11-01)
Kahng, Minsuk Brian
While artificial intelligence (AI) has led to major breakthroughs in many domains, understanding machine learning models remains a fundamental challenge. How can we make AI more accessible and interpretable, or more broadly, human-centered, so that people can easily understand and effectively use these complex models? My dissertation addresses these fundamental and practical challenges in AI through a human-centered approach, by creating novel data visualization tools that are scalable, interactive, and easy to learn and to use. With such tools, users can better understand models by visually exploring how large input datasets affect the models and their results. Specifically, my dissertation focuses on three interrelated parts:
(1) Unified scalable interpretation: developing scalable visual analytics tools that help engineers interpret industry-scale deep learning models at both instance- and subset-level (e.g., ActiVis deployed by Facebook);
(2) Data-driven model auditing: designing visual data exploration tools that support discovery of insights through exploration of data groups over different analytics stages, such as model comparison (e.g., MLCube) and fairness auditing (e.g., FairVis); and (3) Learning complex models by experimentation: building interactive tools that broaden people's access to learning complex deep learning models (e.g., GAN Lab) and browsing raw datasets (e.g., ETable). My research has made significant impact to society and industry. The ActiVis system for interpreting deep learning models has been deployed on Facebook's machine learning platform. The GAN Lab tool for learning GANs has been open-sourced in collaboration with Google, with its demo used by more than 70,000 people from over 160 countries.
(Georgia Institute of Technology, 2019-09-20)
Chen, Shang-Tse
While Artificial Intelligence (AI) has tremendous potential as a defense against real-world cybersecurity threats, understanding the capabilities and robustness of AI remains a fundamental challenge. This dissertation tackles problems essential to successful deployment of AI in security settings and is comprised of the following three interrelated research thrusts. (1) Adversarial Attack and Defense of Deep Neural Networks: We discover vulnerabilities of deep neural networks in real-world settings and the countermeasures to mitigate the threat. We develop ShapeShifter, the first targeted physical adversarial attack that fools state-of-the-art object detectors. For defenses, we develop SHIELD, an efficient defense leveraging stochastic image compression, and UnMask, a knowledge-based adversarial detection and defense framework. (2) Theoretically Principled Defense via Game Theory and ML: We develop new theories that guide defense resources allocation to guard against unexpected attacks and catastrophic events, using a novel online decision-making framework that compels players to employ ``diversified'' mixed strategies. Furthermore, by leveraging the deep connection between game theory and boosting, we develop a communication-efficient distributed boosting algorithm with strong theoretical guarantees in the agnostic learning setting. (3) Using AI to Protect Enterprise and Society: We show how AI can be used in real enterprise environment with a novel framework called Virtual Product that predicts potential enterprise cyber threats. Beyond cybersecurity, we also develop the Firebird framework to help
municipal fire departments prioritize fire inspections. Our work has made multiple important contributions to both theory and practice: our distributed boosting algorithm solved an open problem of distributed learning; ShaperShifter motivated a new DARPA program (GARD); Virtual Product led to two patents; and Firebird was highlighted by National Fire Protection Association as a best practice for using data to inform fire inspections.