Charles Sutton

Charles Sutton

I joined Google in January 2018. My research interests span deep learning, probabilistic machine learning, programming languages, data mining, and software engineering.

I'm especially excited about applying deep learning to huge code bases, finding patterns about what makes for good code, leading to tools to help people write better software.

For older publications (back to 2002), please see my academic web site at the University of Edinburgh.

I maintain a blog with advice for researchers, reflections on academia, the research community, the expatriate lifestyle, and sillier matters.

Authored Publications
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    Preview abstract Identifying invariants in programs is an important program analysis task with applications towards program understanding, vulnerability analysis, and formal verification. Existing tools for identifying invariants rely on dynamic analysis, requiring traces collected from multiple executions in order to produce reliable invariants. We study the application of large language models to invariant prediction, finding that models training on source code and fine-tuned to invariant prediction can perform invariant prediction as static rather than dynamic analysis. Using a scratchpad approach gives the best performance, finding invariants statically of quality comparable to those obtained by a dynamic analysis tool with access to five program traces. View details
    Preview abstract Graph representations of programs are commonly a central element of machine learning for code research. We introduce an open source Python library python_graphs that applies static analysis to construct graph representations of Python programs suitable for training machine learning models. Our library admits the construction of control-flow graphs, data-flow graphs, and composite "program graphs" that combine control-flow, data-flow, syntactic, and lexical information about a program. We present the capabilities and limitations of the library, perform a case-study applying the library to millions of competitive programming submissions, and showcase the library's utility for machine learning research. View details
    Preview abstract When writing programs, people have the ability to tackle a new complex task by decomposing it into smaller and more familiar subtasks. While it is difficult to measure whether neural program synthesis methods have similar capabilities, what we can measure is whether they compositionally generalize, that is, whether a model that has been trained on the simpler subtasks is subsequently able to solve more complex tasks. In this paper, we focus on measuring the ability of learned program synthesizers to compositionally generalize. We first characterize several different axes along which program synthesis methods would be desired to generalize, e.g., length generalization, or the ability to combine known subroutines in new ways that do not occur in the training data. Based on this characterization, we introduce a benchmark suite of tasks to assess these abilities based on two popular existing datasets, SCAN and RobustFill. Finally, we make first attempts to improve the compositional generalization ability of Transformer models along these axes through novel attention mechanisms that draw inspiration from a human-like decomposition strategy. Empirically, we find our modified Transformer models generally perform better than natural baselines, but the tasks remain challenging. View details
    CrossBeam: Learning to Search in Bottom-Up Program Synthesis
    Hanjun Dai
    Kevin Ellis
    International Conference on Learning Representations (ICLR)(2022) (to appear)
    Preview abstract Many approaches to program synthesis perform a search within an enormous space of programs to find one that satisfies a given specification. Prior works have used neural models to guide combinatorial search algorithms, but such approaches still explore a huge portion of the search space and quickly become intractable as the size of the desired program increases. To tame the search space blowup, we propose training a neural model to learn a hands-on search policy for bottom-up synthesis, instead of relying on a combinatorial search algorithm. Our approach, called CrossBeam, uses the neural model to choose how to combine previously-explored programs into new programs, taking into account the search history and partial program executions. Motivated by work in structured prediction on learning to search, CrossBeam is trained on-policy using data extracted from its own bottom-up searches on training tasks. We evaluate CrossBeam in two very different domains, string manipulation and logic programming. We observe that CrossBeam learns to search efficiently, exploring much smaller portions of the program space compared to the state-of-the-art. View details
    PaLM: Scaling Language Modeling with Pathways
    Aakanksha Chowdhery
    Sharan Narang
    Jacob Devlin
    Maarten Bosma
    Hyung Won Chung
    Sebastian Gehrmann
    Parker Schuh
    Sasha Tsvyashchenko
    Abhishek Rao
    Yi Tay
    Noam Shazeer
    Nan Du
    Reiner Pope
    James Bradbury
    Guy Gur-Ari
    Toju Duke
    Henryk Michalewski
    Xavier Garcia
    Liam Fedus
    David Luan
    Barret Zoph
    Ryan Sepassi
    David Dohan
    Shivani Agrawal
    Mark Omernick
    Marie Pellat
    Aitor Lewkowycz
    Erica Moreira
    Rewon Child
    Oleksandr Polozov
    Zongwei Zhou
    Brennan Saeta
    Michele Catasta
    Jason Wei
    Slav Petrov
    Preview abstract Large language models have been shown to achieve remarkable performance across a variety of natural language tasks using few-shot learning, which drastically reduces the number of task-specific training examples needed to adapt the model to a particular application. To further our understanding of the impact of scale on few-shot learning, we trained a 540-billion parameter, densely activated, Transformer language model, which we call Pathways Language Model PaLM. We trained PaLM on 6144 TPU v4 chips using Pathways, a new ML system which enables highly efficient training across multiple TPU Pods. We demonstrate continued benefits of scaling by achieving state-of-the-art few-shot learning results on hundreds of language understanding and generation benchmarks. On a number of these tasks, PaLM 540B achieves breakthrough performance, outperforming the finetuned state-of-the-art on a suite of multi-step reasoning tasks, and outperforming average human performance on the recently released BIG-bench benchmark. A significant number of BIG-bench tasks showed discontinuous improvements from model scale, meaning that performance steeply increased as we scaled to our largest model. PaLM also has strong capabilities in multilingual tasks and source code generation, which we demonstrate on a wide array of benchmarks. We additionally provide a comprehensive analysis on bias and toxicity, and study the extent of training data memorization with respect to model scale. Finally, we discuss the ethical considerations related to large language models and discuss potential mitigation strategies. View details
    Latent Programmer: Discrete Latent Codes for Program Synthesis
    Joey Hong
    David Martin Dohan
    Rishabh Singh
    International Conference on Machine Learning (ICML)(2021)
    Preview abstract In many sequence learning tasks, such as program synthesis and document summarization, a key problem is searching over a large space of possible output sequences. We propose to learn representations of the outputs that is specifically meant for search: rich enough to specify the desired output but compact enough to make search more efficient. An appealing realization of such representation are discrete latent codes, as this naturally allows sophisticated combinatorial search strategies. The latent codes are learned using a self-supervised learning principle, in which first a discrete autoencoder is trained on the output sequences, and then the resulting latent codes are used as intermediate targets for the end-to-end sequence prediction task. Based on these insights, we introduce the Latent Programmer, a program synthesis method that first predicts a discrete latent codes from input/output examples, and then generates the program in the target language. We evaluate the Latent Programmer on two domains: synthesis of string transformation programs, and generation of programs from natural language descriptions. We demonstrate that the discrete latent representation significantly improves synthesis accuracy. View details
    SpreadsheetCoder: Formula Prediction from Semi-structured Context
    Xinyun Chen
    Rishabh Singh
    Hanjun Dai
    Max Lin
    Proceedings of the 38th International Conference on Machine Learning (ICML)(2021)
    Preview abstract Spreadsheet formula prediction has been an important program synthesis problem with many real-world applications. Previous works typically utilize input-output examples as the specification for spreadsheet formula synthesis, where each input-output pair simulates a separate row in the spreadsheet. However, this formulation does not fully capture the rich context in real-world spreadsheets. First, spreadsheet data entries are organized as tables, thus rows and columns are not necessarily independent from each other. In addition, many spreadsheet tables include headers, which provide high-level descriptions of the cell data. However, previous synthesis approaches do not consider headers as part of the specification. In this work, we present the first approach for synthesizing spreadsheet formulas from tabular context, which includes both headers and semi-structured tabular data. In particular, we propose SpreadsheetCoder, a BERT-based model architecture to represent the tabular context in both row-based and column-based formats. We train our model on a large dataset of spreadsheets, and demonstrate that SpreadsheetCoder achieves top-1 prediction accuracy of 42:51%, which is a considerable improvement over baselines that do not employ rich tabular context. Compared to a rule-based system, SpreadsheetCoder assists 82% more users in composing formulas on Google Sheets. View details
    Show Your Work: Scratchpads for Intermediate Computation with Language Models
    Maxwell Nye
    Guy Gur-Ari
    Henryk Witold Michalewski
    David Martin Dohan
    Aitor Lewkowycz
    Maarten Paul Bosma
    David Luan
    Augustus Odena
    Preview abstract Large pre-trained language models perform remarkably well on tasks that can be done “in one pass”, such as generating realistic text (Brown et al., 2020) or synthesizing computer programs (Chen et al., 2021; Austin et al., 2021). However, they struggle with tasks that require unbounded multi-step computation, such as adding integers (Brown et al., 2020) or executing programs (Austin et al., 2021). Surprisingly, we find that these same models are able to perform complex multistep computations—even in the few-shot regime—when asked to perform the operation “step by step”, showing the results of intermediate computations. In particular, we train Transformers to perform multi-step computations by asking them to emit intermediate computation steps into a “scratchpad”. On a series of increasingly complex tasks ranging from long addition to the execution of arbitrary programs, we show that scratchpads dramatically improve the ability of language models to perform multi-step computations. View details
    Learning Semantic Representations to Verify Hardware Designs
    Shobha Vasudevan
    Rishabh Singh
    Hamid Shojaei
    Richard Ho
    Thirty-fifth Conference on Neural Information Processing Systems (NeurIPS)(2021)
    Preview abstract We introduce Design2Vec, a representation learning approach to learn semantic abstractions of hardware designs at the Register Transfer Level (RTL). The key idea of our approach is to design a graph convolution based neural architecture that embeds RTL syntax and semantics. We train the architecture on the task of predicting coverage in the design, given some input test stimulus. We then present an approach to use the learnt RTL representation to automatically generate new tests for unseen coverage locations in the design. Our experimental results demonstrate that Design2Vec outperforms several baseline approaches that do not incorporate the RTL semantics and it can be used to generate instantaneous coverage predictions compared to nightly simulation times. Moreover, the tests generated using Design2Vec result in coverage of design points that are difficult to cover for design verification experts using the current manual approaches for test generation. View details
    Program Synthesis with Large Language Models
    Augustus Odena
    David Martin Dohan
    Ellen Jiang
    Henryk Michalewski
    Maarten Paul Bosma
    Maxwell Nye
    n/a, n/a, n/a(2021), n/a
    Preview abstract Program synthesis is one of the grand challenges of artificial intelligence, but to date practical successes have focused on narrow settings and restricted domains. Large language models trained on massive corpora of web texts which include open-source code, programming websites, and tutorials have the potential to break through this barrier.This paper explores the limits of the current generation of large language models for program synthesis in general purpose programming languages. We evaluate the performance of the language model LaMDA PT [Freitas et al.,2021] on several program synthesis tasks, at a variety of scales ranging from 244M to 137B parameters. First, we introduce a new benchmark, Mostly Basic Programming Problems (MBPP), to measure the ability of these models to synthesize short Python programs from natural language descriptions. The benchmark consists of around 1000 crowd-sourced Python programming problems, designed to be solvable by entry level programmers, covering programming fundamentals, standard library functionality, and so on. Each problem consists of a task description, code solution and automated test-cases. We also introduce a Python version of the MathQA benchmark, which evaluates the ability of the models to synthesize code from more complex text. On both datasets, we evaluate synthesis performance and find that synthesis performance scales log-linearly with model size. In contrast to some previous work, we find that LaMDAPT achieves non-negligible preformance in a few-shot setting, although fine-tuning still performs much better. Thel argest models we consider can synthesize solutions to 58% of the problems from MBPP using few-shot learning with a well-designed prompt; across model sizes, fine-tuning on a held-out portion of the dataset improves performance by about 10 percentage points. Finally, we conduct a thorough error analysis, shedding light on where these models fall short as program synthesizers, what types of programs are most difficult to generate, and how the models might be improved. As part of that analysis, we explore the semantic grounding of these models, finding that even our largest models are generally unable to predict the output of a program given a specific input. View details