Search Results for author: Mehdi Fatemi

Found 14 papers, 9 papers with code

A Dynamical View of the Question of Why

no code implementations14 Feb 2024 Mehdi Fatemi, Sindhu Gowda

We address causal reasoning in multivariate time series data generated by stochastic processes.

Time Series

Successor Features for Efficient Multisubject Controlled Text Generation

no code implementations3 Nov 2023 Meng Cao, Mehdi Fatemi, Jackie Chi Kit Cheung, Samira Shabanian

While large language models (LLMs) have achieved impressive performance in generating fluent and realistic text, controlling the generated text so that it exhibits properties such as safety, factuality, and non-toxicity remains challenging.

Computational Efficiency Language Modelling +1

Systematic Rectification of Language Models via Dead-end Analysis

1 code implementation27 Feb 2023 Meng Cao, Mehdi Fatemi, Jackie Chi Kit Cheung, Samira Shabanian

Other methods rely on rule-based or prompt-based token elimination, which are limited as they dismiss future tokens and the overall meaning of the complete discourse.

Reinforcement Learning (RL)

Semi-Markov Offline Reinforcement Learning for Healthcare

1 code implementation17 Mar 2022 Mehdi Fatemi, Mary Wu, Jeremy Petch, Walter Nelson, Stuart J. Connolly, Alexander Benz, Anthony Carnicelli, Marzyeh Ghassemi

Finally, we apply our new algorithms to a real-world offline dataset pertaining to warfarin dosing for stroke prevention and demonstrate similar results.

Offline RL reinforcement-learning +1

Orchestrated Value Mapping for Reinforcement Learning

1 code implementation ICLR 2022 Mehdi Fatemi, Arash Tavakoli

We present a general convergent class of reinforcement learning algorithms that is founded on two distinct principles: (1) mapping value estimates to a different space using arbitrary functions from a broad class, and (2) linearly decomposing the reward signal into multiple channels.

Ensemble Learning Q-Learning +2

Medical Dead-ends and Learning to Identify High-risk States and Treatments

1 code implementation NeurIPS 2021 Mehdi Fatemi, Taylor W. Killian, Jayakumar Subramanian, Marzyeh Ghassemi

Machine learning has successfully framed many sequential decision making problems as either supervised prediction, or optimal decision-making policy identification via reinforcement learning.

Decision Making

Shortest-Path Constrained Reinforcement Learning for Sparse Reward Tasks

1 code implementation13 Jul 2021 Sungryull Sohn, Sungtae Lee, Jongwook Choi, Harm van Seijen, Mehdi Fatemi, Honglak Lee

We propose the k-Shortest-Path (k-SP) constraint: a novel constraint on the agent's trajectory that improves the sample efficiency in sparse-reward MDPs.

Continuous Control reinforcement-learning +1

An Empirical Study of Representation Learning for Reinforcement Learning in Healthcare

1 code implementation23 Nov 2020 Taylor W. Killian, Haoran Zhang, Jayakumar Subramanian, Mehdi Fatemi, Marzyeh Ghassemi

Reinforcement Learning (RL) has recently been applied to sequential estimation and prediction problems identifying and developing hypothetical treatment strategies for septic patients, with a particular focus on offline learning with observational data.

Open-Ended Question Answering reinforcement-learning +2

Learning to Represent Action Values as a Hypergraph on the Action Vertices

1 code implementation ICLR 2021 Arash Tavakoli, Mehdi Fatemi, Petar Kormushev

To test this, we set forth the action hypergraph networks framework -- a class of functions for learning action representations in multi-dimensional discrete action spaces with a structural inductive bias.

Atari Games Continuous Control +4

Using a Logarithmic Mapping to Enable Lower Discount Factors in Reinforcement Learning

2 code implementations NeurIPS 2019 Harm van Seijen, Mehdi Fatemi, Arash Tavakoli

In an effort to better understand the different ways in which the discount factor affects the optimization process in reinforcement learning, we designed a set of experiments to study each effect in isolation.

General Reinforcement Learning reinforcement-learning +1

Separation of Concerns in Reinforcement Learning

no code implementations15 Dec 2016 Harm van Seijen, Mehdi Fatemi, Joshua Romoff, Romain Laroche

In this paper, we propose a framework for solving a single-agent task by using multiple agents, each focusing on different aspects of the task.

reinforcement-learning Reinforcement Learning (RL)

Policy Networks with Two-Stage Training for Dialogue Systems

no code implementations WS 2016 Mehdi Fatemi, Layla El Asri, Hannes Schulz, Jing He, Kaheer Suleman

Indeed, with only a few hundred dialogues collected with a handcrafted policy, the actor-critic deep learner is considerably bootstrapped from a combination of supervised and batch RL.

Dialogue State Tracking Gaussian Processes +2

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