IJCAI-18 in Stockholm

In July 2018, Hady traveled to Stockholm, Sweden for the International Joint Conference on Artificial Intelligence (IJCAI).  Here, he recounts his experience from the trip.


IJCAI-18 was probably the largest academic conference I ever participated in so far, with 2500 registered attendees.  This was 20% larger than the 2017 conference.  This pronounced growth and outsized congregation is one more sign of the rise (the return?) of Artificial Intelligence or AI.

The conference was held in the massive convention centre Stockholmsmässan

The conference organizer knew how to put up a show.  The scene-stealer during the opening ceremony was definitely the dancing couple of human and robot, gyrating harmoniously to the catchy beat.  Talk about what AI can do!

In the opening ceremony, we were treated to a spectacle of human-robot duet dance.
The conference has 710 papers, and a selective 21% acceptance rate. Singapore more than pulls its weight with 26 papers.

Our Preferred.AI group has 2 papers accepted to the conference.  Both were presented in the Learning Preferences or Rankings session.  The first paper “Modeling Contemporaneous Basket Sequences with Twin Networks for Next-Item Recommendation” by Trong, Hady, and Yuan explores the interaction between two behavioral streams that are occurring concurrently, such as clicking and purchasing on an e-commerce site, and how they can be modeled jointly to improve sequential recommendation.


The second paper “A Bayesian Latent Variable Model of User Preferences with Item Context” by Aghiles and Hady describes a novel graphical model based on Poisson factorization that incorporates item context information, such as which items are viewed together, in addition to  user-item interactions, to improve recommendations especially for users with more limited information.

DFN: Discordant Fraternal Network, a neural network for modeling the interaction between two sequence types of user actions
C2PF: Collaborative Context Poisson Factorization, a graphical model that incorporates item context for recommendation

In addition to the oral presentations in the session, we also got a chance to engage the audience in a poster session.  This allowed deep dives into specific issues, which would take more time and one-on-one discussions.  For instance, from a discussion with a researcher from a large online retailer, I learnt about how prevalent recurrent neural networks were in the company’s sequential recommendation models.

Hady with the two Preferred.AI posters on Contemporaneous Basket Sequences and Collaborative Context Poisson Factorization respectively


The two things that surprised me the most about Stockholm were the weather and the water.  While it was summer then, I was still struck by how a place so far north could be so warm.  No wonder the humidity is high, because water is everywhere!  I grew up with the notion that the neighboring  Indonesia was the largest archipelagic nation.  While that is probably still true in terms of area, little would I expect that the Stockholm archipelago actually have an even greater count of islands than Indonesia.

The view from the Stockholm City Hall, where one of the receptions was held
Ferry to Djurgården, heading to the social program at Skansen, the world’s oldest open-air museum

Prior to the trip, the thing I associated the most with Sweden was the Nobel Prize.  So a visit to Stockholm would not have been complete without experiencing the Nobel Museum.  While the museum has many artefacts connected to various prize winners over the years, the greatest find in my exploration was the cafe!  Some of the chairs have been signed by past prize winners. Well, I may not yet be able to say that I have stepped into their shoes, but now I could say that I once sat on their chairs :).

Nobel Museum, where I probably spent too much time in the museum shop 🙂
In the cafe, one of the chairs was suspended from the ceiling to highlight that the bottom of some chairs may have been signed by prize winners
Signatures of Barack Obama (Peace 2009) and Aung San Suu Kyi (Peace 1991) underneath one chair