Graph Machine Learning
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Everything about graph theory, computer science, machine learning, etc.


If you have something worth sharing with the community, reach out @gimmeblues, @chaitjo.

Admins: Sergey Ivanov; Michael Galkin; Chaitanya K. Joshi
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How node features affect performance of GNN?

This is an open question that I recently thought a bit. In particular, what surprised me are the results from a recent paper on Label Propagation on a particular dataset Rice31 (table below).

You can see that some models achieve 80% accuracy, while others 10% (random guess). In the paper they say that the node features are heterogeneous features such as gender or major, but after speaking with authors it seems they use spectral embeddings instead.

I have tried this dataset with GNN and my results are close to random guess (10%). I tried several variations of GNN as well as node features, but didn't get much higher than 15%. Then I tried GBDT with spectral embeddings and it gave me about 50% accuracy. I haven't tried LP yet on this dataset, but it would be remarkable to see that LP with spectral embeddings can have such a drastic difference with GNN.

This and other experiments led me to think that the paradigm of message passing is too strong, i.e. aggregating information simultaneously among your neighbors may not be a good idea in general. The inductive bias that such model has could be wrong for a particular graph dataset. GNN work on some graph datasets, but how node labels depend on the graph structure is very similar to how message-passing works. In other words, if you were to create a dataset, where a node label equals to an average label of your neighbors, then GNN that does average aggregation would easily learn such dependency. But if your node labels depend on the structure in some counter-intuitive way (for example, by picking a neighbor at random and then assigning its node label), then your GNN with average aggregation would fail. In other words, GNN models don't have to follow message-passing paradigm, they can have very different design principles and that's something that I think we will see in the coming years.
Jraph - A library for graph neural networks in jax.

Jgraph is a new library by DeepMind for constructing GNNs in JAX (autograd computation) and Haiku (writing neural network layers). Could be useful if you cannot use PyTorch.
Graph Machine Learning research groups: Jimeng Sun

I
do a series of posts on the groups in graph research, previous post is here. The 19th is Jimeng Sun, the head of SunLab at UIUC, teaching the courses of Big Data Analytics and Healthcare as well as Computing and Society.

Jimeng Sun (~1981)
- Affiliation: University of Illinois Urbana-Champaign
- Education: Ph.D. at CMU in 2002 (advisor: Christos Faloutsos)
- h-index 66
- Awards: KDD, ICDM, SDM best paper awards
- Interests: drug discovery, GNNs, graph mining
Planarity game

If you need some time to procrastinate and you want to do it with graphs, here is a fun game to play, called Tronix2. You just need to make the drawn graphs planar. There are several clones of this game (here and here), which even explain how to generate planar graphs. And here is Numberphile video about planar graphs.
Golden Knowledge Graph

Golden is a Silicon Valley startup building a knowledge database (similar to Wikipedia) — a good example how knowledge graphs can be commercialized.
Undergraduate Math Student Pushes Frontier of Graph Theory

A new article at QuantaMagazine about 21 year old who improved results of Erdős and Szekeres on the upper bound for two-color Ramsey numbers. Informally, Ramsey numbers can be explained as "how big graphs can get before patterns inevitably emerge". This is in addition to the recent proof for lower bounds, also covered in Quanta.
ICLR 2021 Graph Papers

Here is a list of graph papers with their final scores. This is in addition to the list for all the papers. Overall, 74 papers (out of 208 graph papers) increased their scores and 18 decreased.
Open Access Theses and Dissertations

Seeking for an inspiration for your dissertation or maybe want to check the latest monolithic works in graph community, take a look at OATD portal. Here is for example a search for all dissertations that have graph in their title, resulting in ~400 PhD and ~100 MSc theses just in 2016-2020 period.
Don't crack under pressure

I remember when I was interning at HKUST during my master's years I had a chance to see a motivational presentation for freshmen from one of the tenured professors there. One of the things he was emphasizing is that PhD is stressful experience with lots of uncertainty and you should keep being focused, brave and don't crack under the pressure. Here is a funny story that demonstrates it. A guy realized he has a bug 2 weeks before submitting his PhD thesis and asked MathOverflow community to help him to fix it, luckily it worked out well.
Graph Mining & Learning Workshop NeurIPS 2020

NeurIPS 2020 just started and there is a good workshop by Google Research on graph mining (by Bryan Perozzi and others). To see the videos you need to register for expo but it's free. Then you will have links to videos. There is also a slide deck with 312 pages about many interesting topics.

Update: it seems there is a bug in the registration panel, so you can access the schedule and videos in this page.
ML News

New website that covers ML news, a clone of hacker news but dedicated to ML. In addition to Lobste.rs and Slashdot.
MoleculeKit: Machine Learning Methods for Molecular Property Prediction and Drug Discovery

MoleculeKit is a new framework that deals with molecule predictions. It represents molecules as both graphs and sequences and then apply GNN or kernel together with BERT for downstream molecular tasks (predicting properties of nodes or graphs).
Privacy-Preserving Deep Learning Over Graphs

60 slides of overview of the emerging field of privacy-preserving GNNs. Could be interesting if you search for a new research topic.
Graph Machine Learning research groups: Max Welling

I do a series of posts on the groups in graph research, previous post is here. The 20th is Max Welling, the head of the Amsterdam Machine Learning Lab. He co-founded a startup Scyfer BV that was acquired by Qualcomm, where he serves as VP of technologies. Max has a diverse research interests, including lately developments in graph machine learning field.

Max Welling (1968)
- Affiliation: University of Amsterdam, Qualcomm
- Education: Ph.D. at Utrecht University in 1998 (advisor: Gerard 't Hooft)
- h-index 73
- Awards: ECCV Koenderink Prize, ICML best papers.
- Interests: equivariant networks, variational encoders, GNNs.
Deep Graph Networks Reading Group

There is a reading group at Bicocca University (Milan, Italy). Next session will happen on Monday, 14th December at 10am (UK time). The paper "HATS a hierarchical graph attention network for stock movement prediction" will be discussed. If you want to join you can get a link by contacting @Sagax_ita or via [email protected].