This repository contains the implementation to scale Relational Graph Convolutional Network (R-GCN) training with graph summaries, proposed in the thesis Scaling R-GCN training with Graph Summaries and Entity Embedding Transfer.

Relational Graph Convolutional Network (R-GCN) training on real-world graphs is challenging. Storing gradient information during R-GCN training on real-world graphs, exceeds available memory on most single devices. Recent work demonstrated to scale R-GCN training with a summary graph. The appropriate graph summarization technique is often unknown and graph and task dependent. Overcoming this problem, we propose R-GCN pre-training on multiple graph summaries, produced with attribute and (k)-forward bisimulation summarization techniques. With pre-training on graph summaries, multiple entity embeddings and one set R-GCN weights can be obtained. We applied Summation, MultiLayer Perceptron and Multi-Head Attention models to transfer multiple entity embeddings and R-GCN weights to a new R-GCN model. With the new R-GCN model we conducted full-graph training for entity type prediction. Our contribution to existing research is three-fold, as this work demonstrated how: graph summaries reduce parameters for R-GCN training, while maintaining or improving R-GCN performance; the creation of graph summaries can be included in R-GCN training to maintain or improve R-GCN performance, while reducing computational time; graph summaries in combination with Multi-Layer Perceptron and Multi-Head Attention can be applied to scale R-GCN training and maintain or improve R-GCN performance, while freezing the gradients of the R-GCN weights after summary graph pre-training.

To use the repository, we recommend creating a virtual environment, e.g. with conda. Use requirements.txt to install the dependencies:

conda create -n scaling_rgcn python=3.8 
conda activate scaling_rgcn
pip install -r requirements.txt

The AM dataset is too large push to github. Download the AM dataset, including graph summaries, here. Unpack AM.zip and add like ./graphs/AM.

The ./graphs folder contains graphs datasets. Each graph folder, e.g.AM, contains attribute summaries (attr) and (k)-forward bisimulaiton summaries (bisim). The attribute graph summaries are stored in ./graphs/{dataset}/attr/sum. The (k)-forward bisimulaiton summaries are stored in ./graphs/{dataset}/bisim/sum For each graph summary (attribute and (k)-forward bisimulation) there exists a map file in ./graphs/{dataset}/attr/map. ./graphs/{dataset}/one/ contains a single summary graph (either attribute or (k)-forward bisimulation) which must be added munually.

The incoming, outgoing and the incoming/outgoing attribute summary graphs can be created for a graph dataset with graphs/createAttributeSum.py. Summary graphs and corresponding node mapping files will be created and saved to ./graphs/{dataset}/attr/sum and ./graphs/{dataset}/attr/map, respectively. Create the attribute summary graphs of a graph dataset with the follwing command:

python graphs/createAttributeSum.py -dataset AIFB

For the creation of (k)-forward bisimulation summary graphs we refer to FLUID.

We provide example commands to reproduce our experiments. The commands be should run from the root directory of the repository. The aim is to scale R-GCN training for entity type prediction. We display examples for running the experiments on the AIFB dataset (-dataset AIFB) for 5 iterations (-i 5). By default the experiments run for 51 epochs. There are three different models to choose from: summation, mlp and attention. For a detailed description of the models we refer to the thesis (section 5.2).

The following command runs the experiment where pre-training on the summary graphs, present in the .graphs/AIFB/attr folder, occurs. After training on graph summaries, the embeddings and R-GCN weights are transferred to a new R-GCN model. Then, full original graph training is carried out for entity type prediction. The program will automatically save results to ./results. Also, the results are plotted automatically.

python main.py -dataset AIFB -sum attr -i 5 -exp attention

To run the single summary graph experiment, copy the desired graph summary to the ./graphs/AIFB/one/sum. Copy its complementing map graph to ./graphs/AIFB/one/map.

python main.py -dataset AIFB -sum one -i 5 -exp attention

It can be decided to transfer either the entity embeddings or the R-GCN weights from summary graph training with the following commands:

python main.py -sum attr -i 5 -exp attention -w_trans False -e_trans True
python main.py -sum attr -i 5 -exp attention -w_trans True -e_trans False

When entity embeddings are not transferred from summary graph pre-training, the entity embedding for training on the full original graph gets newly initialized.

The gradients of the R-GCN weights can be frozen after transferring them from the summary graph model with -w_grad. Note that the mlp and attention model contain layer spicific weights and the summation does not. We recommend to use the following command with the mlp and attention model only:

python main.py -sum attr -i 5 -exp attention -w_grad False 

The entity embedding can be frozen or unfrozen by setting -e_freeze to True or False. By default, the transferred embedding is frozen: -e_freeze True.