Open AI Review One

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In the Open AI Scholars program, we write a recap of learning and progress every two weeks. This post is the first such recap.

Overview

The Open AI Scholars Program is a six-month Deep Learning research program. I work with my mentor John Schulman at the intersection of reinforcement learning and language models.

Starting Project

My mentor proposed this idea in our first meeting: Using upvotes as a reward function to fine-tune language models’ output. I’ll refer to this project by “Upvotes As Rewards.” This project has some similarities to the recent Open AI paper Learning to Summarize from Human Preferences in the sense that it uses a novel RL reward function to fine-tune a language model.

“Upvotes as Rewards” is compelling because it develops a novel reward function and is ambitious but achievable. This project uses my mentor’s RL expertise while also reflecting the large scale trend towards language models.

Starting Syllabus

For “Upvotes As Rewards,” I will need to utilize RL and language models. I have some background for RL because I have read Barto and Sutton and have also implemented Tabular Q-Learning and Deep Q-Learning to play generalized tic-tac-toe. My particular focus in RL will be on understanding Online Policy Gradient methods, culminating in understanding Proximal Policy Optimization. For Language Models, I don’t have any background, so I will learn what is necessary to understand GPT-3. I will eventually implement proximal policy optimization and transformer models from scratch and integrate them into “Upvotes As Rewards.”

Prototype Plan

I will start by using baseline implementations and pre-trained models to accelerate the prototype development process.

  • Once I understand Proximal Policy Optimization, I will use an existing Open AI Baselines implementation for the prototype.
  • Once I understand GPT-3, I will use a pre-trained language model implementation for the prototype.
  • I will choose a website with prompts, responses, and upvotes to serve as the source of training data (e.g., Reddit or Twitter) and implement a web crawler to fetch the data I need.
  • I predict that knowing enough about reinforcement learning and language models to begin working on the project will take four weeks.
  • I predict that implementing the web crawler and gauging the data quality will take two to three weeks.
  • I predict that implementing making a pre-trained transformer work on the data will take two to four weeks.
  • I predict that implementing and training a stable reward model will take two to four weeks.
  • This timeframe still gives me time to run many experiments and potentially implement a transformer model and PPO from scratch during the training and hyperparameter tuning period.

Next two weeks

I have chosen a subset of tasks to complete within the next two weeks.

  • I plan to develop a big-picture view of my project by reading “Learning to Summarize from Human Feedback” and discussing it with one of the paper’s authors.
  • I plan to complete my understanding of Proximal Policy Optimization by doing the following:
    • Reading chapter three of John Schulman’s thesis so that I can understand Trust Region Policy Optimization. I read chapters one and two this past week.
    • Reading the Generalized Advantage Estimators Paper
    • Reading the Proximal Policy Optimization Paper
  • I plan to blog twice a week, highlighting interesting statistical details in the papers I read.
  • I plan to start studying transformers by learning about autoregressive models from the first two lectures of the UC Berkeley graduate class on Deep Unsupervised Learning.