CS Team Wins the ICCV 2019 Learning-to-Drive Challenge

Students participated in the International Conference on Computer Vision (ICCV) 2019 Learning-to-Drive Challenge as part of the Deep Learning (DL) course taught by adjunct associate professor Iddo Drori. The winning team’s findings were presented at the Autonomous Driving workshop in Seoul, Korea.

The goal of the competition is to develop DL driving models — predicting steering wheel angle and vehicle speed is given large-scale training data and using advanced deep learning techniques. Two teams, composed of students from the computer science (CS) department and the Data Science Institute (DSI), won the challenge in all major categories ranking first and second place.

“Winning the top three categories in this international challenge is an excellent achievement,” said adjunct associate professor Iddo Drori. “I am very proud to have mentored the teams to the finish line.”

As part of the unique DL course curriculum, students get to compete in common task framework competitions which enable them to test the waters in the real world while advancing science. This semester Drori and teaching assistants Manik Goyal and Benedikt Dietmar performed feasibility tests on the Learning-to-Drive Challenge and found it in line with the course goals.

Students used the Drive 360 dataset to design, develop and train a driving model. Over the course of three weeks, teams worked on and improved their submissions competing with groups from across the world. Students were given cloud resources to develop their models even further. The effort paid off with the CS and DSI students at the top of the competition leaderboard. In order to claim victory, they had to quickly write up and submit their findings.

CS graduate students Michael J Diodato and Yu Li won first place, while DSI graduate students Antonia Lovjer and Minsu Yeom won second place.

Steven Nowick Bids Farewell to the CS Department

After 26 years in the computer science department, professor Steven Nowick is retiring. Friends, colleagues, and those dear to him recently gathered to celebrate his teaching and academic career — one that has pushed the asynchronous community to be more widely noticed and accepted. Nowick walks away with a body of work that is as diverse and nuanced as the next chapter of his life — composing music. 

Left to right : Grant Chorley, Steven Nowick,
David Conte (chair of composition, San Francisco Conservatory), Fred Blum, Joel Feigin (former music professor, UC Santa Barbara) at the Conservatoire Americaine, Fontainebleau, France (1975).

Many probably do not know that he has a B.A. from Yale University in music and an M.A. in music composition from Columbia University, where his master’s thesis was symphony. The better part of his 20s was spent on a music career, during which time he studied privately with composer David Diamond, and in France with the legendary music teacher Nadia Boulanger. 

However, he decided to shift gears and retrain in computer science (CS) when he hit 30 years old. After two years of brushing up on CS concepts, including a class taught by Steven Feiner that first introduced him to digital hardware, he applied and was accepted to the PhD program at Stanford University in 1986. 

While at Stanford, his interest in asynchronous systems was cemented when he started to work on research with professor David Dill.  In 1993, he found himself back at Columbia as an assistant professor. In his first year, he recognized the need for a Computer Engineering program in the engineering school, and worked with two colleagues from computer science and electrical engineering departments to establish the degree that was later expanded to include a masters program. In his second year at Columbia, he co-founded the IEEE ASYNC symposium, the premier international forum for researchers to present their latest findings in the area of asynchronous digital design, which is still thriving after 25 years.

“Computer engineering is entirely to Steve’s credit that it grew to what it is today,” said Kathy McKeown, the Henry and Gertrude Rothschild Professor of Computer Science, who looked through her emails all the way back to the time when she was the department chair in the late 90s for her tribute to Nowick. “It is also because of his persistence and dedication as head of the strategic planning committee, that our faculty has grown.”

Also at the party, Zvi Galil, former computer science professor and dean of the School of Engineering and Applied Sciences, shared, “In the good old days we couldn’t even hire one faculty, now they can hire five in a year.” At the time in the late 90s there were less than 20 faculty, currently there are 59 faculty. Said another colleague, Shree Nayar, “Thank you for all that you’ve done for the department, we would not look the same if not for you.”

Through the years, Nowick has taught and mentored hundreds of students. “He is an amazing academic father,” said Montek Singh, a former PhD student who is now a tenured associate professor at the University of North Carolina at Chapel Hill. Singh shared how when they were working on MOUSETRAP:  High-Speed Transition-Signaling Asynchronous Pipelines, they brainstormed for days working out every little detail. And then they brainstormed even more to come up with the name, which is actually an acronym – Minimum Overhead Ultra-high-Speed Transition-signaling Asynchronous Pipeline. Continued Singh, “I can only hope to be half as good to my PhD students as he is.” 

Left to right : Michael Theobald (PhD student), George Faldamis (MS student), Cheoljoo Jeong (PhD student), Melinda Agyekum (PhD student), Steven Nowick, Martha Helfer (Nowick’s wife), Cheng-Hong Li (MS student), Montek Singh (PhD student)

The party was also attended by a number of his other former graduate students, post-docs, and outside colleagues, including former PhD student Michael Theobald, a research scientist in formal verification at D.E. Shaw Research, who served as “master of ceremonies.” His asynchronous colleagues Ivan Sutherland (the Turing Award winning inventor of interactive computer graphics and virtual reality) and Marly Roncken flew out from Oregon, and computer science professor Rajit Manohar came down from Yale.

“Steve is a highly ambitious person with a lot of passion, a tremendous persistence and a lot of perseverance,” said Jeannette Wing, the Avanessians Director of the Data Science Institute and computer science professor. In 2016, Nowick established a working group at the Data Science Institute, and in 2018 worked with Wing to turn it into a center – The Center for Computing Systems for Data-Driven Science. He has gathered 45 faculty from across the university to explore the design and application of large-scale computing systems for data-driven scientific discovery. It is multi-disciplinary and brings together diverse researchers at Columbia in three areas: computing systems, data science and machine learning, and large-scale computational application areas in science, engineering and medicine. Qiang Du, a professor from Applied Physics and Applied Mathematics, and associate computer science professor Martha Kim are now co-chairs of the center.

Left to right : Columbia Executive Vice President for Research Michael Purdy, Steven Nowick, and professor Sebastian Will, physics department

As chair of the working group, in 2017, he organized an on-campus inaugural symposium, attracting 150 participants, which included leading speakers from IBM, D.E. Shaw Research and NASA Goddard. In 2019, as his final major act as center chair, he co-organized the NY Scientific Data Summit jointly with nearby Brookhaven National Laboratory, to showcase regional research on data-driven science, and to forge closer bonds between the two institutions.

Of course, asynchronous research and activities to advance the field were happening simultaneously with all these other activities. Nowick has been one of the leaders in the revival of clockless, or asynchronous, digital hardware systems. While most digital systems today are synchronous, built using a central clock, increasingly the challenge of assembling large, complex and heterogeneous systems – with dozens to millions of processors and memory units – is becoming unworkable under centralized control. The vision of asynchronous systems has seen a resurgence in the last twenty years, and Nowick has been at the forefront. Such systems, assembled with “Lego-like” hardware building blocks, which are plugged together and communicate locally, promise to overcome some of the extreme barriers faced in the microelectronics industry, providing low energy, ease of assembly, high performance, and reliable operation.

Recent asynchronous advances include “brain-inspired” (i.e. neuromorphic) chips from IBM (TrueNorth) and Intel (Loihi). Nowick has collaborated closely with AMD Research, migrating his asynchronous on-chip networks into the company’s advanced technology, and experimentally demonstrating significant benefits in power, performance and area, over their synchronous commercial designs. He and his students have also introduced an influential set of computer-aided design (CAD) software tools, optimization algorithms and analysis techniques, for asynchronous circuits and systems. In addition, he has worked closely over the years with IBM Research, Boeing and NASA on asynchronous design projects.

Nowick is an IEEE Fellow (2009), a recipient of an Alfred P. Sloan Research Fellowship (1995), received NSF CAREER (1995) and RIA (1993) awards, and he is also a Senior Member of the ACM. He received Best Paper Awards at the IEEE International Conference on Computer Design (1991, 2012) and the IEEE Async Symposium (2000). He also acted as program chair at various workshops and conferences, as well as served on leading journal editorial boards, such as IEEE Design & Test Magazine, IEEE Transactions on Computer-Aided Design, IEEE Transactions on VLSI Systems, and ACM Journal on Emerging Technologies in Computer Systems, and served as a guest editor for a special issue of the Proceedings of the IEEE. He holds 13 issued US patents, and his research has been supported by over 20 grants and gifts. In recognition of his teaching, he also received the SEAS Alumni Distinguished Faculty Teaching Award in 2011.

But the pull of music has become stronger in recent years. 

“In the back of my mind I always knew I would return to it and I should do it now while I can still do it well, rather than when I’m in my 80s or 90s,” said Nowick.

He plays the piano and his focus will be classical composition. He has written music for string quartet, orchestra, choir, piano, cello, two flutes, and for voice and piano. He is writing new compositions and looks forward to his music being performed. 

“Music will be his act two,” said Montek Singh. “So in a sense he’s come full circle.”

CS Professors Part of the Inaugural J.P. Morgan Faculty Research Awards

The J.P. Morgan AI Research Awards 2019 partners with research thinkers across artificial intelligence. The program is structured as a gift that funds a year of study for a graduate student.


Prediction semantics and interpretations that are grounded in real data
Principal Investigator: Daniel Hsu Computer Science Department & Data Science Institute

The importance of transparency in predictive technologies is by now well-understood by many machine learning practitioners and researchers, especially for applications in which predictions may have serious impacts on human lives (e.g., medicine, finance, criminal justice). One common approach to providing transparency is to ensure interpretability in the models and predictions produced by an application, or to accompany predictions with explanations. Interpretations and explanations may help individuals understand predictions that affect them, and also help developers reason about failure cases of their applications.

However, there are numerous possibilities for what constitutes a suitable interpretation or explanation, and the semantics of such provided by existing systems are not always clear. 

Suppose, for example, that a bank uses a linear model to predict whether or not a loan applicant will forfeit on a loan. A natural strategy is to seek a sparse linear model, which are often touted as highly interpretable. However, attributing significance to variables with non-zero regression coefficients (e.g., zip-code) and not others (e.g., race, age) is suspect when variables may be correlated. Moreover, an explanation based on pointing to individual variables or other parameters of a model ignores the source of the model itself: the training data (e.g., a biased history of borrowers and forfeiture outcomes) and the model fitting procedure. Invalid or inappropriate explanations may create a “transparency fallacy” that creates more problems than are solved.

The researchers propose a general class of mechanisms that provide explanations based on training or validation examples, rather than any specific component or parameters of a predictive model. In this way, the explanation will satisfy two key features identified in successful human explanations: the explanation will be contrastive, allowing an end-user to compare the present data to the specific examples chosen from the training or validation data, and the explanation will be pertinent to the actual causal chain that results in the prediction in question. These features are missing in previous systems that seek to explain predictions based on machine learning methods.

“We expect this research to lead to new methods for interpretable machine learning,” said Daniel Hsu, the principal investigator of the project. Because the explanations will be based on actual training examples, the methods will be widely applicable, in essentially any domain where examples can be visualized or communicated to a human. He continued, “This stands in contrast to nearly all existing methods for explanatory machine learning, which either require strong assumptions like linearity or sparsity, or do not connect to the predictive model of interest or the actual causal chain leading to a given prediction of interest.”


Efficient Formal Safety Analysis of Neural Networks
Principal Investigators: Suman Jana Computer Science Department, Jeannette M. Wing Computer Science Department & Data Science Institute, Junfeng Yang Computer Science Department

Over the last few years, artificial intelligence (AI), in particular Deep Learning (DL) and Deep Neural Networks (DNNs), has made tremendous progress, achieving or surpassing human-level performance for a diverse set of tasks including image classification, speech recognition, and playing games such as Go. These advances have led to widespread adoption and deployment of DL in critical domains including finance, healthcare, autonomous driving, and security. In particular, the financial industry has embraced AI in applications ranging from portfolio management (“Robo-Advisor”), algorithmic trading, fraud detection, loan and insurance underwriting, sentiment and news analysis, customer service, to sales.  

“Machine learning models are used in more and more safety and security-critical applications such as autonomous driving and medical diagnosis,” said Suman Jana, one of the principal investigators of the project. “Yet they are known to be fragile and frequently mispredicts on edge cases.“ 

In many critical domains including finance and autonomous driving, such incorrect behaviors can lead to disastrous consequences such as a gigantic loss in automated financial trading or a fatal collision of a self-driving car. For example, in 2016, a Google self-driving car crashed into a bus because it expected the bus to yield under a set of rare conditions but the bus did not. Also in 2016, a Tesla car in autopilot crashed into a trailer because the autopilot system failed to recognize the trailer as an obstacle due to its ‘white color against a brightly lit sky’ and the ‘high ride height.’

Before AI can become the next technological revolution, it must be robust against such corner-case inputs and does not cause disasters. The researchers believe AI robustness is one of the biggest challenges that needs to be solved in order to fully tame AI for good.

“Our research aims to create novel tools to verify that a machine learning model will not mispredict on certain important input ranges, ensuring safety and security,” said Junfeng Yang, one of the investigators of the research. 

The proposed work enables rigorous analysis of autonomous AI systems and machine learning (ML) algorithms, enabling data scientists to (1) verify that their AI models function correctly within certain input regions and violate no critical properties they specify (e.g., bidding price is never higher than a given maximum) or (2) locate all sub-regions where their models misbehave and repair their model accordingly. This capability will also enable data scientists to explain and interpret the outputs from autonomous AI systems and ML algorithms by understanding how different input regions may lead to different output predictions. Said Yang,”If successful, our work will dramatically boost the robustness, explainability, and interpretability of today’s autonomous AI systems and ML algorithms, benefiting virtually every individual, business, and government that relies on AI and ML.”