Portrait de Prakash Panangaden

Prakash Panangaden

Membre académique principal
Sujets de recherche
Apprentissage par renforcement
Modèles probabilistes
Raisonnement
Théorie de l'apprentissage automatique
Théorie de l'information quantique

Biographie

Prakash Panangaden a étudié la physique à l'Indian Institute of Technology de Kanpur, en Inde. Il a obtenu une maîtrise en physique de l'Université de Chicago, où il a étudié l'émission stimulée des trous noirs. Il a ensuite obtenu un doctorat en physique de l'Université du Wisconsin-Milwaukee, dans lequel il s’est penché sur la théorie quantique des champs dans un espace-temps courbe.

Il a été professeur adjoint d'informatique à l'Université Cornell, où il a principalement travaillé sur la sémantique des langages de programmation concurrents. Depuis 1990, il travaillait à l'Université McGill. Au cours des 25 dernières années, il s'est intéressé à de nombreux aspects des processus de Markov : équivalence des processus, caractérisation logique, approximation et métrique.

Récemment, il a travaillé sur l'utilisation des métriques pour améliorer l'apprentissage des représentations. Il a également publié des articles sur la physique, l'information quantique et les mathématiques pures. Il est membre de la Société royale du Canada et de l'Association for Computing Machinery (ACM).

Étudiants actuels

Maîtrise recherche - McGill
Co-superviseur⋅e :

Publications

Towards an AAK Theory Approach to Approximate Minimization in the Multi-Letter Case
We study the approximate minimization problem of weighted finite automata (WFAs): given a WFA, we want to compute its optimal approximation … (voir plus)when restricted to a given size. We reformulate the problem as a rank-minimization task in the spectral norm, and propose a framework to apply Adamyan-Arov-Krein (AAK) theory to the approximation problem. This approach has already been successfully applied to the case of WFAs and language modelling black boxes over one-letter alphabets \citep{AAK-WFA,AAK-RNN}. Extending the result to multi-letter alphabets requires solving the following two steps. First, we need to reformulate the approximation problem in terms of noncommutative Hankel operators and noncommutative functions, in order to apply results from multivariable operator theory. Secondly, to obtain the optimal approximation we need a version of noncommutative AAK theory that is constructive. In this paper, we successfully tackle the first step, while the second challenge remains open.
Bisimulation metrics and norms for real-weighted automata
Borja Balle
Pascale Gourdeau
Extracting Weighted Automata for Approximate Minimization in Language Modelling
Optimal Spectral-Norm Approximate Minimization of Weighted Finite Automata
We address the approximate minimization problem for weighted finite automata (WFAs) with weights in …
MICo: Improved representations via sampling-based state similarity for Markov decision processes
Tyler Kastner
Mark Rowland
We present a new behavioural distance over the state space of a Markov decision process, and demonstrate the use of this distance as an effe… (voir plus)ctive means of shaping the learnt representations of deep reinforcement learning agents. While existing notions of state similarity are typically difficult to learn at scale due to high computational cost and lack of sample-based algorithms, our newly-proposed distance addresses both of these issues. In addition to providing detailed theoretical analyses, we provide empirical evidence that learning this distance alongside the value function yields structured and informative representations, including strong results on the Arcade Learning Environment benchmark.
MICo: Learning improved representations via sampling-based state similarity for Markov decision processes
Tyler Kastner
Mark Rowland
We present a new behavioural distance over the state space of a Markov decision process, and demonstrate the use of this distance as an eff… (voir plus)ective means of shaping the learnt representations of deep reinforcement learning agents. While existing notions of state similarity are typically difficult to learn at scale due to high computational cost and lack of sample-based algorithms, our newly-proposed distance addresses both of these issues. In addition to providing detailed theoretical analysis
Bisimulation metrics and norms for real-weighted automata
Borja Balle
Pascale Gourdeau
A Distributional Analysis of Sampling-Based Reinforcement Learning Algorithms
We present a distributional approach to theoretical analyses of reinforcement learning algorithms for constant step-sizes. We demonstrate it… (voir plus)s effectiveness by presenting simple and unified proofs of convergence for a variety of commonly-used methods. We show that value-based methods such as TD(
A Distributional Analysis of Sampling-Based Reinforcement Learning Algorithms
Computation, Logic, Games, and Quantum Foundations. The Many Facets of Samson Abramsky
Bob. Coecke
Luke Ong
Samson. Abramsky
Computation, Logic, Games, and Quantum Foundations. The Many Facets of Samson Abramsky
Bob. Coecke
Luke Ong
Samson. Abramsky