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

KDD.SG Tutorial on Image Classification Using CNN (Materials)

Our appreciation to KDD.SG (Singapore Chapter of SIGKDD) and DSSG (DataScience Singapore) for jointly organizing and inviting us to deliver a public tutorial on June 9.  Tuan and Hady delivered a tutorial on image classification using convolutional neural networks, focusing on two applications, namely: face emotion recognition and visual sentiment analysis.

Hady opened the tutorial on Image Classification using CNN
Tuan explained the implementation of Multi Layer Perceptron on Tensorflow
The audience was actively involved and participating in the tutorial

For those who missed the tutorial, you may find the materials here for your own self-practice.  A video recording of the event can be found below.


SDSC – DSSG Data Science Meetup (Videos)

We are grateful to SDSC (Singapore Data Science Consortium and DSSG (DataScience Singapore) for organizing the June 7 meetup, and to the hundred attendees who gave us an opportunity to share some of our recent work.

After opening remarks by Caroline from SDSC, Hady gave the first technical talk titled “Modeling Preferences from Multi-Modal Data: A Deep Learning Exploration”.  The talk covered several works by our group in modeling user preferences from several modalities such as social networks, images, as well as sequences.

Focusing on modeling text, in particular about word embeddings and how sentiment infusion could improve the performance of word embeddings on several text classification tasks, Maksim gave a talk titled “SentiVec: Sentiment-Infused Word Embeddings”.

Rounding up the coverage of modalities, Aghiles gave a talk titled “C2PF: A Poisson Latent Factor Model of User Preferences with Item Context” on incorporating the effects of item context to improve recommendations.

You may find the slides of the three talks here.  It was a fruitful session, and we got a chance to meet many new contacts from academia and industry.  Looking forward to the next opportunity to get in touch.

Visual Sentiment Analysis

“A picture is worth a thousand words.”

So they say. Indeed, some images could capture certain moments so vividly that they become iconic and timeless.

Could a picture speak of the sentiment of the photographer?

Intuitively, that seems probable.  After all, in the choice of scenery or angle or other tricks up the sleeve of a photographer, the picture taken is essentially a rendering of what the photographer sees.


In pursuit of an empirical answer to what might have also been a philosophical question, we conduct research on a data set of images found within online reviews of restaurants crawled from Yelp.  With the advent of mobile phones, many online reviewers now prolifically include photos within their reviews, recounting their experiences as well as their sentiments textually and visually.

What is visual sentiment analysis?

To test the above hypothesis, we formulate a problem known as visual sentiment analysis.  Given an image, we seek to determine whether the image is positive (i.e., found within a review with rating of 4 or 5 on a scale of 5) or negative (i.e., associated with a rating of 1 or 2).  We build a binary classifier based on a deep learning framework called Convolutional Neural Networks.  Our model architecture shown below is reminiscent of AlexNet for object detection, with a twist in its application to binary sentiment classification.  We describe the details of this base model in a paper authored by Tuan and Hady and published in the ACM Multimedia Conference 2017.

VSCNN: Convolutional Neural Networks for Visual Sentiment Analysis

To cut a fascinating story short, we find that the trained visual sentiment analysis classifier performs significantly better than random, implying that indeed there are signals within an image that help to convey the overall sentiment of the review writer.

What do positive images look like?

Below we show some examples of images classified as positive.  Happy faces and celebrations seem to mark happy moments.  Note that this is a general image classification, and not specifically about facial emotion recognition (which itself is an interesting but distinct problem).  For another set of examples, if one can afford to dine at restaurants with a view, chances are the experience would be positive.

Examples of Images with Positive Sentiment

What do negative images look like?

Well, no one likes paying too much (or perhaps even paying at all?).  It is always a bummer to discover something that does not belong on one’s plate.

Examples of Images with Negative Sentiment

Interesting as it is, this is not yet the end of our exploration.  There are other factors that we would consider to improve the performance of visual sentiment analysis.  That’s the subject of a future blog post.  If you really can’t wait, here is the paper.

Visiting Russia

Braving the depths of winter, Hady and Maksim visited Russia in late February to early March, when the temperature stayed below zero throughout.  Parks were seas of white, yet rivers were solid ground.


Plodding wearily on icy sidewalks and snow-banked curbs, as well as zipping cheerily around town on Yandex Taxi, we visited a number of institutions to increase the awareness of postgraduate programmes at SMU Information Systems, as well as to share the research work of the Preferred.AI group, covering topics on learning user preferences from multi-modal data such as images, text, and social networks.


Our first visit was to the colorful and bustling Moscow.  We were excited to visit the esteemed PhysTech, also known as Moscow Institute of Physics and Technology or MIPT, as well as the progressive AI Lab of Sberbank, which is the largest bank in Russia.  In the evening before leaving Moscow, we gave a talk at the well-attended Data Science Meetup organized by Avito.  Fortunately, the session was recorded, and we are happy to share the video below.



Our next visit was to the serenely beautiful Saint Petersburg.  Not only does the city have some great museums such as Hermitage, but the city itself is also virtually a living museum.  In between art-laden walks, we mingled with academics at national research universities such as ITMO University and Saint Petersburg Academic University.  As computer scientists, we would not want to miss a visit to the iconic CSClub.  Our talk there was also recorded, with similar content, but from a different angle and with a nice audio too.



All in all, the trip was insightful and educational, in more ways than one!  We learnt tons, and got to know great people.  Looking forward to the next opportunity.


Hady & Maksim on Rooftop Overlooking Ligovsky Prospekt, Saint Petersburg


… to the home page of Preferred.AI.  We are a close-knit group of data mining and machine learning researchers based in SMU, focusing on learning user preferences from data.  On these pages you would find information about our activities, profiles, projects, and publications.