A*Net: A* Networks

This is the official codebase of the paper

A*Net: A Scalable Path-based Reasoning Approach for Knowledge Graphs

Zhaocheng Zhu*, Xinyu Yuan*, Mikhail Galkin, Sophie Xhonneux, Ming Zhang, Maxime Gazeau, Jian Tang

Overview

A*Net is a scalable path-based method for knowledge graph reasoning. Inspired by the classical A* algorithm, A*Net learns a neural priority function to select important nodes and edges at each iteration, which significantly reduces time and memory footprint for both training and inference.

A*Net is the first path-based method that scales to ogbl-wikikg2 (2.5M entities, 16M triplets). It also enjoys the advantages of path-based methods such as inductive capacity and interpretability.

Here is a demo of A*Net with a ChatGPT interface. By reasoning on the Wikidata knowledge graph, ChatGPT produces more grounded predictions and less hallucination.

This codebase contains implementation for A*Net and its predecessor NBFNet.

Installation

The dependencies can be installed via either conda or pip. A*Net is compatible with 3.7 <= Python <= 3.10 and PyTorch >= 1.13.0.

From Conda

conda install pytorch cudatoolkit torchdrug pytorch-sparse -c pytorch -c pyg -c milagraph
conda install ogb easydict pyyaml openai -c conda-forge

From Pip

pip install torch torchdrug torch-sparse
pip install ogb easydict pyyaml openai

Usage

To run A*Net, use the following command. The argument -c specifies the experiment configuration file, which includes the dataset, model architecture, and hyperparameters. You can find all configuration files in config/.../*.yaml. All the datasets will be automatically downloaded in the code.

python script/run.py -c config/transductive/fb15k237_astarnet.yaml --gpus [0]

For each experiment, you can specify the number of GPU via the argument --gpus. You may use --gpus null to run A*Net on a CPU, though it would be very slow. To run A*Net with multiple GPUs, launch the experiment with torchrun

torchrun --nproc_per_node=4 script/run.py -c config/transductive/fb15k237_astarnet.yaml --gpus [0,1,2,3]

For the inductive setting, there are 4 different splits for each dataset. You need to additionally specify the split version with --version v1.

ChatGPT Interface

We provide a ChatGPT interface of A*Net, where users can interact with A*Net through natural language. To play with the ChatGPT interface, download the checkpoint here and run the following command. Note you need an OpenAI API key to run the demo.

export OPENAI_API_KEY=your-openai-api-key
python script/chat.py -c config/transductive/wikikg2_astarnet_visualize.yaml --checkpoint wikikg2_astarnet.pth --gpus [0]

Visualization

A*Net supports visualization of important paths for its predictions. With a trained model, you can visualize the important paths with the following line. Please replace the checkpoint with your own path.

python script/visualize.py -c config/transductive/fb15k237_astarnet_visualize.yaml --checkpoint /path/to/astarnet/experiment/model_epoch_20.pth --gpus [0]

Parameterize with your favourite GNNs

A*Net is designed to be general frameworks for knowledge graph reasoning. This means you can parameterize it with a broad range of message-passing GNNs. To do so, just implement a convolution layer in reasoning/layer.py and register it with @R.register. The GNN layer is expected to have the following member functions

def message(self, graph, input):
    ...
    return message

def aggregate(self, graph, message):
    ...
    return update

def combine(self, input, update):
    ...
    return output

where the arguments and the return values are

• graph (data.PackedGraph): a batch of subgraphs selected by A*Net, with graph.query being the query embeddings of shape (batch_size, input_dim).
• input (Tensor): node representations of shape (graph.num_node, input_dim).
• message (Tensor): messages of shape (graph.num_edge, input_dim).
• update (Tensor): aggregated messages of shape (graph.num_node, *).
• output (Tensor): output representations of shape (graph.num_node, output_dim).

To support the neural priority function in A*Net, we need to additionally provide an interface for computing messages

def compute_message(self, node_input, edge_input):
   ...
   return msg_output

You may refer to the following tutorials of TorchDrug

• Graph Data Structures
• Graph Neural Network Layers

Frequently Asked Questions

1. The code is stuck at the beginning of epoch 0.

   This is probably because the JIT cache is broken. Try rm -r ~/.cache/torch_extensions/* and run the code again.

Citation

If you find this project useful, please consider citing the following paper

@article{zhu2022scalable,
  title={A*Net: A Scalable Path-based Reasoning Approach for Knowledge Graphs},
  author={Zhu, Zhaocheng and Yuan, Xinyu and Galkin, Mikhail and Xhonneux, Sophie and Zhang, Ming and Gazeau, Maxime and Tang, Jian},
  journal={arXiv preprint arXiv:2206.04798},
  year={2022}
}