SymFormer: End-to-end symbolic regression using transformer-based architecture

TL;DR

SymFormer uses a Transformer-based architecture for symbolic regression, achieving fast and accurate inference.

cs.LG 🔴 Advanced 2022-05-31 42 views
Martin Vastl Jonáš Kulhánek Jiří Kubalík Erik Derner Robert Babuška
symbolic regression Transformer machine learning constant optimization fast inference

Key Findings

Methodology

SymFormer employs a Transformer-based architecture to jointly predict symbols and constants. The model is trained on millions of formulas, using autoregressive generation for symbolic expressions and corresponding constants. By leveraging cross-attention and self-attention mechanisms, the model efficiently generates formulas and utilizes local gradient search to optimize constants.

Key Results

  • SymFormer achieved an R2 of 0.99998 on the Nguyen benchmark with an inference time of 47.5 seconds, significantly outperforming NSRS and DSO.
  • In the Livermore benchmark, SymFormer achieved an R2 of 0.99996 with an inference time of just 43 seconds.
  • Ablation studies confirmed the importance of constant prediction and local gradient search.

Significance

SymFormer is significant in the field of symbolic regression, addressing the inefficiencies of traditional methods in constant optimization. Its rapid inference capability makes it promising for real-time applications and provides new tools for scientific research.

Technical Contribution

SymFormer breaks the limitations of traditional symbolic regression methods by jointly predicting symbols and constants, enhancing the model's expressive power and accuracy. Its use of Transformer architecture opens new research directions for symbolic regression.

Novelty

SymFormer is the first to achieve joint prediction of symbols and constants, significantly improving inference speed and accuracy compared to existing methods. Its innovation lies in using a Transformer architecture for symbolic regression tasks.

Limitations

  • The model may overfit when handling complex functions, especially during constant optimization.
  • Inference time increases for multivariate functions.

Future Work

Future work can explore more complex function structures and constant optimization over larger ranges. Additionally, researching how to train the model with less data is an important direction.

AI Executive Summary

Symbolic regression involves automatically deriving mathematical formulas from observed data, with traditional methods like genetic programming being inefficient and time-consuming. SymFormer uses a Transformer-based architecture to achieve joint prediction of symbols and constants, significantly improving inference speed and accuracy.

SymFormer is trained on millions of formulas, using autoregressive generation for symbolic expressions and corresponding constants. Its innovation lies in simultaneously predicting symbols and constants and utilizing local gradient search to optimize constants. Experimental results show that SymFormer excels in multiple benchmarks, with inference speeds significantly faster than existing methods.

While SymFormer has made significant advances in symbolic regression, challenges remain in handling complex functions. Future research can explore more complex function structures and constant optimization over larger ranges to further enhance the model's performance and applicability.

Deep Analysis

Background

Symbolic regression involves automatically deriving mathematical formulas, widely used in fields like physics, robotics, and machine learning. Traditional methods like genetic programming require significant computational resources and are slow in inference. Recently, neural network methods have emerged, with Transformer-based models showing potential in symbolic regression.

Core Problem

Traditional symbolic regression methods are inefficient in constant optimization, leading to slow inference and suboptimal results. Improving inference speed while maintaining accuracy is a significant challenge.

Innovation

SymFormer achieves joint prediction of symbols and constants through a Transformer-based architecture. Its innovation lies in simultaneously generating symbols and constants and using local gradient search to optimize constants, enhancing the model's expressive power and accuracy.

Methodology

  • �� Use Transformer architecture for joint prediction of symbols and constants.
  • �� Train on millions of formulas, using autoregressive generation for symbolic expressions.
  • �� Leverage cross-attention and self-attention mechanisms for efficient generation.
  • �� Optimize constants using local gradient search to improve model accuracy.

Experiments

The experimental design includes evaluating SymFormer's performance on multiple benchmarks. Top-K sampling is used to generate candidate formulas, and local gradient search optimizes constants. Results show that SymFormer excels in multiple benchmarks, with inference speeds significantly faster than existing methods.

Results

SymFormer achieved an R2 of 0.99998 on the Nguyen benchmark with an inference time of 47.5 seconds, significantly outperforming NSRS and DSO. Ablation studies confirmed the importance of constant prediction and local gradient search.

Applications

SymFormer can be used to automatically derive formulas in scientific research, improving research efficiency. Its rapid inference capability makes it promising for real-time applications.

Limitations & Outlook

While SymFormer has made significant advances in symbolic regression, challenges remain in handling complex functions. Future research can explore more complex function structures and constant optimization over larger ranges.

Plain Language Accessible to non-experts

Imagine you're in a kitchen, and SymFormer is like a smart chef assistant. It can automatically generate recipes (mathematical formulas) based on the ingredients (input data), and it does so very quickly. Traditional methods are like writing recipes by hand, slow and prone to errors. SymFormer not only generates recipes quickly but also automatically adjusts the spices (constants) to ensure the dish's flavor (accuracy) is just right.

ELI14 Explained like you're 14

Imagine you're playing a game, and SymFormer is like a super helper that can quickly find the cheat codes (mathematical formulas) for you. Traditional methods are like figuring it out on your own, slow and easy to get stuck. SymFormer not only finds the codes quickly but also automatically adjusts the strategy (constants) to ensure you can easily win. Isn't that cool?

Glossary

Symbolic Regression

The task of automatically deriving mathematical formulas from observed data.

Used to describe natural processes or technical systems.

Transformer

A deep learning model architecture based on attention mechanisms.

Used for joint prediction of symbols and constants.

Autoregressive

A prediction method that generates sequences step by step.

Used for generating symbolic expressions.

Local Gradient Search

A method to optimize constants to improve model accuracy.

Used to optimize constants generated by SymFormer.

Top-K Sampling

A method to select the top K most likely results from a probability distribution.

Used to generate candidate formulas.

Open Questions Unanswered questions from this research

  • 1 How to improve SymFormer's performance on more complex function structures?
  • 2 How to train SymFormer with less data?
  • 3 How to further optimize constants to improve model accuracy?

Applications

Immediate Applications

Scientific Research

SymFormer can be used to automatically derive mathematical formulas in scientific research, improving research efficiency.

Long-term Vision

Real-time Applications

SymFormer's rapid inference capability makes it promising for real-time applications, such as autonomous driving and robotics control.

Abstract

Many real-world problems can be naturally described by mathematical formulas. The task of finding formulas from a set of observed inputs and outputs is called symbolic regression. Recently, neural networks have been applied to symbolic regression, among which the transformer-based ones seem to be the most promising. After training the transformer on a large number of formulas (in the order of days), the actual inference, i.e., finding a formula for new, unseen data, is very fast (in the order of seconds). This is considerably faster than state-of-the-art evolutionary methods. The main drawback of transformers is that they generate formulas without numerical constants, which have to be optimized separately, so yielding suboptimal results. We propose a transformer-based approach called SymFormer, which predicts the formula by outputting the individual symbols and the corresponding constants simultaneously. This leads to better performance in terms of fitting the available data. In addition, the constants provided by SymFormer serve as a good starting point for subsequent tuning via gradient descent to further improve the performance. We show on a set of benchmarks that SymFormer outperforms two state-of-the-art methods while having faster inference.

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