LibKGE is a PyTorch-based library for efficient training, evaluation, and hyperparameter optimization of knowledge graph embeddings (KGE). It is highly configurable, easy to use, and extensible. Other KGE frameworks are listed below.

The key goal of LibKGE is to foster reproducible research into (as well as meaningful comparisons between) KGE models and training methods. As we argue in our ICLR 2020 paper (see video), the choice of training strategy and hyperparameters are very influential on model performance, often more so than the model class itself. LibKGE aims to provide clean implementations of training, hyperparameter optimization, and evaluation strategies that can be used with any model. Every potential knob or heuristic implemented in the framework is exposed explicitly via well-documented configuration files (e.g., see here and here). LibKGE also provides the most common KGE models and new ones can be easily added (contributions welcome!).

For link prediction tasks, rule-based systems such as AnyBURL are a competitive alternative to KGE.

Table of contents

1. Features
2. Results and pretrained models
3. Quick start
4. Using LibKGE
5. Currently supported KGE models
6. Adding a new model
7. Known issues
8. Changelog
9. Other KGE frameworks
10. How to cite

Features

• Training
  • Training types: negative sampling, 1vsAll, KvsAll
  • Losses: binary cross entropy (BCE), Kullback-Leibler divergence (KL), margin ranking (MR)
  • All optimizers and learning rate schedulers of PyTorch supported
  • Early stopping
  • Checkpointing
  • Stop (e.g., via Ctrl-C) and resume at any time
• Hyperparameter tuning
  • Grid search, manual search, quasi-random search (using Ax), Bayesian optimization (using Ax)
  • Highly parallelizable (multiple CPUs/GPUs on single machine)
  • Stop and resume at any time
• Evaluation
  • Entity ranking metrics: Mean Reciprocal Rank (MRR), HITS@k with/without filtering
  • Drill-down by: relation type, relation frequency, head or tail
• Extensive logging
  • Logging for training, hyper-parameter tuning and evaluation in machine readable formats to facilitate analysis
• KGE models
  • All models can be used with or without reciprocal relations
  • RESCAL (code, config)
  • TransE (code, config)
  • DistMult (code, config)
  • ComplEx (code, config)
  • ConvE (code, config)
  • RelationalTucker3/TuckER (code, config)
  • CP (code, config)
  • SimplE (code, config)
  • RotatE (code, config)
• Embedders
  • Lookup embedder (code, config)
  • Projection embedder (code, config)

Results and pretrained models

We list some example results (filtered MRR and HITS@k on test data) obtained with LibKGE below. These results are obtained by running automatic hyperparameter search as described here.

These results are not necessarily the best results that can be achieved using LibKGE, but they are comparable in that a common experimental setup (and equal amount of work) has been used for hyperparameter optimization for each model. Since we use filtered MRR for model selection, our results may not be indicative of the achievable model performance for other validation metrics (such as HITS@10, which has been used for model selection elsewhere).

We report performance numbers on the entire test set, including the triples that contain entities not seen during training. This is not done consistently throughout existing KGE implementations: some frameworks remove unseen entities from the test set, which leads to a perceived increase in performance (e.g., roughly add +3pp to our WN18RR MRR numbers for this method of evaluation).

We also provide pretrained models for these results. Each pretrained model is given in the form of a LibKGE checkpoint, which contains the model as well as additional information (such as the configuration being used). See the documentation below on how to use checkpoints.

FB15K-237 (Freebase)

	MRR	Hits@1	Hits@3	Hits@10	Config file	Pretrained model
RESCAL	0.356	0.263	0.393	0.541	config.yaml	1vsAll-kl
TransE	0.313	0.221	0.347	0.497	config.yaml	NegSamp-kl
DistMult	0.343	0.250	0.378	0.531	config.yaml	NegSamp-kl
ComplEx	0.348	0.253	0.384	0.536	config.yaml	NegSamp-kl
ConvE	0.339	0.248	0.369	0.521	config.yaml	1vsAll-kl

WN18RR (Wordnet)

	MRR	Hits@1	Hits@3	Hits@10	Config file	Pretrained model
RESCAL	0.467	0.439	0.480	0.517	config.yaml	KvsAll-kl
TransE	0.228	0.053	0.368	0.520	config.yaml	NegSamp-kl
DistMult	0.452	0.413	0.466	0.530	config.yaml	KvsAll-kl
ComplEx	0.475	0.438	0.490	0.547	config.yaml	1vsAll-kl
ConvE	0.442	0.411	0.451	0.504	config.yaml	KvsAll-kl

FB15K (Freebase)

	MRR	Hits@1	Hits@3	Hits@10	Config file	Pretrained model
TransE	0.676	0.542	0.787	0.875	config.yaml	NegSamp-kl
DistMult	0.841	0.806	0.863	0.903	config.yaml	1vsAll-kl
ComplEx	0.838	0.807	0.856	0.893	config.yaml	1vsAll-kl
ConvE	0.825	0.781	0.855	0.896	config.yaml	KvsAll-bce

WN18 (Wordnet)

	MRR	Hits@1	Hits@3	Hits@10	Config file	Pretrained model
RESCAL	0.948	0.943	0.951	0.956	config.yaml	1vsAll-kl
TransE	0.553	0.315	0.764	0.924	config.yaml	NegSamp-bce
DistMult	0.941	0.932	0.948	0.954	config.yaml	1vsAll-kl
ComplEx	0.951	0.947	0.953	0.958	config.yaml	KvsAll-kl
ConvE	0.947	0.943	0.949	0.953	config.yaml	1vsAll-kl

Wikidata5M (Wikidata)

LibKGE supports large datasets such as Wikidata5M (4.8M entities). The result given below was found by automatic hyperparameter search similar to the one used for the smaller datasets above, but with some values fixed (training with shared negative sampling, embedding dimension: 128, batch size: 1024, optimizer: Adagrad, regularization: weighted). We ran 30 pseudo-random configurations for 20 epochs, and then reran the configuration that performed best on validation data for 200 epochs.

	MRR	Hits@1	Hits@3	Hits@10	Config file	Pretrained model
ComplEx	0.301	0.245	0.331	0.397	config.yaml	NegSamp-kl

Yago3-10 (YAGO)

The result given below was found by the same automatic hyperparameter search used for Wikidata5M. We reran the configuration that performed best on validation data for 400 epochs.

	MRR	Hits@1	Hits@3	Hits@10	Config file	Pretrained model
ComplEx	0.551	0.476	0.596	0.682	config.yaml	NegSamp-kl

CoDEx

CoDEx is a Wikidata-based KG completion benchmark. The results here have been obtained using the automatic hyperparameter search used for the Freebase and WordNet datasets, but with fewer epochs and Ax trials for CoDEx-M and CoDEx-L. See the CoDEx paper (EMNLP 2020) for details.

CoDEx-S

	MRR	Hits@1	Hits@3	Hits@10	Config file	Pretrained model
RESCAL	0.404	0.293	0.4494	0.623	config.yaml	1vsAll-kl
TransE	0.354	0.219	0.4218	0.634	config.yaml	NegSamp-kl
ComplEx	0.465	0.372	0.5038	0.646	config.yaml	1vsAll-kl
ConvE	0.444	0.343	0.4926	0.635	config.yaml	1vsAll-kl
TuckER	0.444	0.339	0.4975	0.638	config.yaml	KvsAll-kl

CoDEx-M

	MRR	Hits@1	Hits@3	Hits@10	Config file	Pretrained model
RESCAL	0.317	0.244	0.3477	0.456	config.yaml	1vsAll-kl
TransE	0.303	0.223	0.3363	0.454	config.yaml	NegSamp-kl
ComplEx	0.337	0.262	0.3701	0.476	config.yaml	KvsAll-kl
ConvE	0.318	0.239	0.3551	0.464	config.yaml	NegSamp-kl
TuckER	0.328	0.259	0.3599	0.458	config.yaml	KvsAll-kl

CoDEx-L

	MRR	Hits@1	Hits@3	Hits@10	Config file	Pretrained model
RESCAL	0.304	0.242	0.3313	0.419	config.yaml	1vsAll-kl
TransE	0.187	0.116	0.2188	0.317	config.yaml	NegSamp-kl
ComplEx	0.294	0.237	0.3179	0.400	config.yaml	1vsAll-kl
ConvE	0.303	0.240	0.3298	0.420	config.yaml	1vsAll-kl
TuckER	0.309	0.244	0.3395	0.430	config.yaml	KvsAll-kl

Quick start

# retrieve and install project in development mode
git clone https://github.com/uma-pi1/kge.git
cd kge
pip install -e .

# download and preprocess datasets
cd data
sh download_all.sh
cd ..

# train an example model on toy dataset (you can omit '--job.device cpu' when you have a gpu)
kge start examples/toy-complex-train.yaml --job.device cpu

Using LibKGE

LibKGE supports training, evaluation, and hyperparameter tuning of KGE models. The settings for each task can be specified with a configuration file in YAML format or on the command line. The default values and usage for available settings can be found in config-default.yaml as well as the model- and embedder-specific configuration files (such as lookup_embedder.yaml).

Train a model

First create a configuration file such as:

job.type: train
dataset.name: fb15k-237

train:
  optimizer: Adagrad
  optimizer_args:
    lr: 0.2

valid:
  every: 5
  metric: mean_reciprocal_rank_filtered

model: complex
lookup_embedder:
  dim: 100
  regularize_weight: 0.8e-7

To begin training, run one of the following:

# Store the file as `config.yaml` in a new folder of your choice. Then initiate or resume
# the training job using:
kge resume <folder>

# Alternatively, store the configuration anywhere and use the start command
# to create a new folder
#   <kge-home>/local/experiments/<date>-<config-file-name>
# with that config and start training there.
kge start <config-file>

# In both cases, configuration options can be modified on the command line, too: e.g.,
kge start <config-file> config.yaml --job.device cuda:0 --train.optimizer Adam

Various checkpoints (including model parameters and configuration options) will be created during training. These checkpoints can be used to resume training (or any other job type such as hyperparameter search jobs).

Resume training

All of LibKGE's jobs can be interrupted (e.g., via Ctrl-C) and resumed (from one of its checkpoints). To resume a job, use:

kge resume <folder>

# Change the device when resuming
kge resume <folder> --job.device cuda:1

By default, the last checkpoint file is used. The filename of the checkpoint can be overwritten using --checkpoint.

Evaluate a trained model

To evaluate trained model, run the following:

# Evaluate a model on the validation split
kge valid <folder>

# Evaluate a model on the test split
kge test <folder>

By default, the checkpoint file named checkpoint_best.pt (which stores the best validation result so far) is used. The filename of the checkpoint can be overwritten using --checkpoint.

Hyperparameter optimization

LibKGE supports various forms of hyperparameter optimization such as grid search or Bayesian optimization. The search type and search space are specified in the configuration file. For example, you may use Ax for SOBOL (pseudo-random) and Bayesian optimization.

The following config file defines a search of 10 SOBOL trials (arms) followed by 20 Bayesian optimization trials:

job.type: search
search.type: ax

dataset.name: wnrr
model: complex
valid.metric: mean_reciprocal_rank_filtered

ax_search:
  num_trials: 30
  num_sobol_trials: 10  # remaining trials are Bayesian
  parameters:
    - name: train.batch_size
      type: choice
      values: [256, 512, 1024]
    - name: train.optimizer_args.lr
      type: range
      bounds: [0.0003, 1.0]
    - name: train.type
      type: fixed
      value: 1vsAll

Trials can be run in parallel across several devices:

# Run 4 trials in parallel evenly distributed across two GPUs
kge resume <folder> --search.device_pool cuda:0,cuda:1 --search.num_workers 4

# Run 3 trials in parallel, with per GPUs capacity
kge resume <folder> --search.device_pool cuda:0,cuda:1,cuda:1 --search.num_workers 3

Export and analyze logs and checkpoints

Extensive logs are stored as YAML files (hyperparameter search, training, validation). LibKGE provides a convenience methods to export the log data to CSV.

kge dump trace <folder>

The command above yields CSV output such as this output for a training job or this output for a search job. Additional configuration options or metrics can be added to the CSV files as needed (using a keys file).

Information about a checkpoint (such as the configuration that was used, training loss, validation metrics, or explored hyperparameter configurations) can also be exported from the command line (as YAML):

kge dump checkpoint <checkpoint>

Configuration files can also be dumped in various formats.

# dump just the configuration options that are different from the default values
kge dump config <config-or-folder-or-checkpoint>

# dump the configuration as is
kge dump config <config-or-folder-or-checkpoint> --raw

# dump the expanded config including all configuration keys
kge dump config <config-or-folder-or-checkpoint> --full

Help and other commands

# help on all commands
kge --help

# help on a specific command
kge dump --help

Use a pretrained model in an application

Using a trained model trained with LibKGE is straightforward. In the following example, we load a checkpoint and predict the most suitable object for a two subject-relations pairs: ('Dominican Republic', 'has form of government', ?) and ('Mighty Morphin Power Rangers', 'is tv show with actor', ?).

import torch
from kge.model import KgeModel
from kge.util.io import load_checkpoint

# download link for this checkpoint given under results above
checkpoint = load_checkpoint('fb15k-237-rescal.pt')
model = KgeModel.create_from(checkpoint)

s = torch.Tensor([0, 2,]).long()             # subject indexes
p = torch.Tensor([0, 1,]).long()             # relation indexes
scores = model.score_sp(s, p)                # scores of all objects for (s,p,?)
o = torch.argmax(scores, dim=-1)             # index of highest-scoring objects

print(o)
print(model.dataset.entity_strings(s))       # convert indexes to mentions
print(model.dataset.relation_strings(p))
print(model.dataset.entity_strings(o))

# Output (slightly revised for readability):
#
# tensor([8399, 8855])
# ['Dominican Republic'        'Mighty Morphin Power Rangers']
# ['has form of government'    'is tv show with actor']
# ['Republic'                  'Johnny Yong Bosch']

For other scoring functions (score_sp, score_po, score_so, score_spo), see KgeModel.

Currently supported KGE models

LibKGE currently implements the following KGE models:

• RESCAL (code, config)
• TransE (code, config)
• DistMult (code, config)
• ComplEx (code, config)
• ConvE (code, config)
• RelationalTucker3 (code, config)
• CP (code, config)
• SimplE (code, config)
• RelationalTucker3/TuckER (code, config)
• RotatE (code, config)

The examples folder contains some configuration files as examples of how to train these models.

We welcome contributions to expand the list of supported models! Please see CONTRIBUTING for details and feel free to initially open an issue.

Adding a new model or embedder

To add a new model to LibKGE, extend the KgeModel class. A model is made up of a KgeEmbedder to associate each subject, relation and object to an embedding, and a KgeScorer to score triples given their embeddings.

The model implementation should be stored under <kge-home>/kge/model/<model-name>.py, its configuration options under <kge-home>/kge/model/<model-name>.yaml and its import has to be added to <kge-home>/kge/model/__init__.py.

The embdedder implementation should be stored under <kge-home>/kge/model/embedder/<embedder-name>.py, its configuration options under <kge-home>/kge/model/embedder/<embedder-name>.yaml and its import has to be added to <kge-home>/kge/model/__init__.py.

Known issues

Changelog

See here.

Other KGE frameworks

Other KGE frameworks:

• Graphvite
• AmpliGraph
• OpenKE
• PyKEEN

KGE projects for publications that also implement a few models:

• ConvE
• KBC

PRs to this list are welcome.

How to cite

Please cite the following publication to refer to the experimental study about the impact of training methods on KGE performance:

@inproceedings{
  ruffinelli2020you,
  title={You {CAN} Teach an Old Dog New Tricks! On Training Knowledge Graph Embeddings},
  author={Daniel Ruffinelli and Samuel Broscheit and Rainer Gemulla},
  booktitle={International Conference on Learning Representations},
  year={2020},
  url={https://openreview.net/forum?id=BkxSmlBFvr}
}

If you use LibKGE, please cite the following publication:

@inproceedings{
  libkge,
  title="{L}ib{KGE} - {A} Knowledge Graph Embedding Library for Reproducible Research",
  author={Samuel Broscheit and Daniel Ruffinelli and Adrian Kochsiek and Patrick Betz and Rainer Gemulla}",
  booktitle={Proceedings of the 2020 Conference on Empirical Methods in Natural Language Processing: System Demonstrations},
  year={2020},
  url={https://www.aclweb.org/anthology/2020.emnlp-demos.22},
  pages = "165--174",
}