Introducing Sayan Ranu

The DAIR group and the department of CS&E are happy to welcome Sayan Ranu to our ranks as faculty. Here is Sayan in his own words:

Hello everyone,

This is Sayan and I joined the CSE department at IIT-D exactly two months back (21st December 2016).

Let me start by answering the question I hear most often when I meet someone new at IIT D: what are my research interests? Given that I am a member of DAIR group, it is obvious that my interests lie in Data Science. Data Science, however, is a fairly broad area and the particular topics that I focus on are Graph Mining and Spatio-temporal data analytics.

Graph Mining: Querying and mining graph datasets have been extensively studied and continue being one of the most active research areas. However, an overwhelming majority is centred on analysing static graph properties. In today’s world, graphs often change with time. In social networks, new nodes get added every second. Links between nodes change as old acquaintances get forgotten and new friendships are forged. The content at each node (such as a Facebook wall post) change with time and propagate through the network. In road networks, the volume of traffic changes every minute. While some parts of the network can cope with higher traffic, others get bogged down by congestions, which in turn, alters the typical commuting behaviour resulting in the congestion further spreading to other parts of the network. What are the “laws” governing the evolution of these dynamic networks? If we partially observe a trend, can we predict its cascading effect? Can we mine patterns that highlight trends deviating from the expected behaviour? These are some of the fundamental questions that drive my research efforts.

Spatio-temporal data analytics: Today, buses, cabs, and ambulances are tracked through GPS-aided navigation systems to collect data and improve services. Users voluntarily share their locations on social networking sites like Facebook and Twitter through “check-ins” made from smartphones. Movements of people are also captured through involuntary means in various services such as geo-tagged photo albums in sites like Flickr, Google+ and Facebook, credit card transactions, messaging apps like WhatsApp and Viber, and base-station connectivity in cell phone call detail records. Querying, mining and modelling this data is central to a multitude of smart city applications, such as congestion modelling, urban resource management, security, and infrastructure development. Given a budget X, where should we construct X flyovers so that they maximise the reduction in traffic congestion? Can we model and predict the movement of a criminal from his/her past activities collected through call detail records? Can we group residents of a city into communities based on their check-ins? Who are the errant bus and cab drivers that pose risk to other commuters? Another set of fascinating questions that remain to be answered.

What else do I like outside research? Well, I love sports, particularly cricket and tennis. If there is any regular group on campus playing cricket or tennis, do let me know. I would definitely join.


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