Clifford Seth Stein (born December 14, 1965), a computer scientist, is a professor of industrial engineering and operations research at Columbia University in New York, NY, where he also holds an appointment in the Department of Computer Science. Stein is chair of the Industrial Engineering and Operations Research Department at Columbia University. Prior to joining Columbia, Stein was a professor at Dartmouth College in New Hampshire. Stein's research interests include the design and analysis of algorithms, combinatorial optimization, operations research, network algorithms, scheduling, algorithm engineering and computational biology. Stein has published many influential papers in the leading conferences and journals in his fields of research, and has occupied a variety of editorial positions including in the journals ACM Transactions on Algorithms, Mathematical Programming, Journal of Algorithms, SIAM Journal on Discrete Mathematics and Operations Research Letters.

In reinforcement learning, agents have successfully used environments modeled with Markov decision processes (MDPs). However, in many problem domains, an agent may suffer from noisy observations or random times until its subsequent decision. While partially observable Markov decision processes (POMDPs) have dealt with noisy observations, they have yet to deal with the unknown time aspect. Of course, one could discretize the time, but this leads to Bellman's Curse of Dimensionality. To incorporate continuous sojourn-time distributions in the agent's decision making, we propose that partially observable semi-Markov decision processes (POSMDPs) can be helpful in this regard. We extend \citet{Spaan2005a} randomized point-based value iteration (PBVI) \textsc{Perseus} algorithm used for POMDP to POSMDP by incorporating continuous sojourn time distributions and using importance sampling to reduce the solver complexity. We call this new PBVI algorithm with importance sampling for POSMDPs -- \textsc{ChronosPerseus}. This further allows for compressed complex POMDPs requiring temporal state information by moving this information into state sojourn time of a POMSDP. The second insight is that keeping a set of sampled times and weighting it by its likelihood can be used in a single backup; this helps further reduce the algorithm complexity. The solver also works on episodic and non-episodic problems. We conclude our paper with two examples, an episodic bus problem and a non-episodic maintenance problem.

" "In light of the explosive growth in the amount of data and the diversity of computing applications, efficient algorithms are needed now more than ever. This beautifully written, thoughtfully organized book is the definitive introductory book on the design and analysis of algorithms. The first half offers an effective method to teach and study algorithms; the second half then engages more advanced readers and curious students with compelling material on both the possibilities and the challenges in this fascinating field."--Shang-Hua Teng, University of Southern California ""Introduction to Algorithms, " the'bible' of the field, is a comprehensive textbook covering the full spectrum of modern algorithms: from the fastest algorithms and data structures to polynomial-time algorithms for seemingly intractable problems, from classical algorithms in graph theory to special algorithms for string matching, computational geometry, and number theory. The revised third edition notably adds a chapter on van Emde Boas trees, one of the most useful data structures, and on multithreaded algorithms, a topic of increasing importance."--Daniel Spielman, Department of Computer Science, Yale University "As an educator and researcher in the field of algorithms for over two decades, I can unequivocally say that the Cormen book is the best textbook that I have ever seen on this subject.

Introduction to Algorithms, the'bible' of the field, is a comprehensive textbook covering the full spectrum of modern algorithms: from the fastest algorithms and data structures to polynomial-time algorithms for seemingly intractable problems, from classical algorithms in graph theory to special algorithms for string matching, computational geometry, and number theory. The revised third edition notably adds a chapter on van Emde Boas trees, one of the most useful data structures, and on multithreaded algorithms, a topic of increasing importance.

A panel of esteemed cryptographers at RSA 2017 expressed doubt over artificial intelligence's applicability in the cybersecurity space, tossing cold water on what otherwise appeared to be a hot technology at the conference. "The real problem is that what AI and machine learning is great at is lots of data and dealing with it effectively and what we're dealing with, with the serious attacks are anomalous situations and AI does not look like it's going to be useful there," said Susan Landau, professor of cybersecurity policy and professor of computer science at Worcester Polytechnic Institute, during the session earlier this week. Adi Shamir, Borman professor of computer science at the Weizmann Institute in Israel, said that AI would likely be helpful in defending against attacks when they happen, but not sniffing out threats before they materialize. "I think that AI can be very helpful on the defensive side," said Shamir, who earlier this month was named a recipient of the 2017 Japan Prize. "I doubt it would be so helpful for new zero days because this requires more ingenuity and originality. But when you talk about finding deviations from normal behavior, I think that AI systems are going to be very useful... Ronald Rivest, a professor at the MIT Institute, said that he was "skeptical" that AI would have a significant impact on security. He did, however, acknowledge that AI played an important role in spreading fake news and propaganda during the U.S. election. "There are AI bots talking on chat rooms... adding misinformation and disinformation," said Rivest. "I can imagine 10 or 15 years from now, we're going to find ourselves competing to find the humans among just a sea of bots talking to each other intelligently." But Shamir had a different vision for AI as it becomes super intelligent in the next 15 years: I can foresee a situation which we'll give all of the available data about cybersecurity to this program and it will think for a long time and then say in a calm voice, 'In order to save the Internet I'll have to kill it,'" said Shamir, facetiously.

SAN FRANCISCO--Cryptographers said at the RSA Conference Tuesday they're skeptical that advances in quantum computing and artificial intelligence will profoundly transform computer security. "I'm skeptical there will be much of an impact," Ron Rivest, a MIT professor and inventor of several symmetric key encryption algorithms, said early at the annual Cryptographers' Panel here. Susan Landau, a professor who specializes in cybersecurity policy and computer science at Worcester Polytechnic Institute, said that while artificial intelligence can be helpful when it comes to processing lots of data effectively, she doesn't think it will be useful in fingering out series attacks or anomalous situations. Adi Shamir, Borman Professor of Computer Science at the Weizmann Institute, said he was optimistic about AI's potential when it comes to defense – anything that involves finding deviations in behavior – but said he doubts it can ever be used in offensive sense, such as in identifying zero days, something he said requires more ingenuity and originality. The discussion was steered by a report recently released by the Global Risk Institute on the emergence of quantum computing technologies.

It was unusual for Martin Hellman, a professor of electrical engineering at Stanford University, to present two papers on cryptography at the International Symposium on Information Theory in October 1977. Under normal circumstances, Steve Pohlig or Ralph Merkle, the doctoral students who also had worked on the papers, would have given the talks, but on the advice of Stanford's general counsel, it was Hellman who spoke. The reason for the caution was that an employee of the U.S. National Security Agency, J.A. Meyer, had claimed publicly discussing their new approach to encryption would violate U.S. law prohibiting the export of weapons to other countries. Stanford's lawyer did not agree with that interpretation of the law, but told Hellman it would be easier for him to defend a Stanford employee than it would be to defend graduate students, so he recommended Hellman give the talk instead. Whitfield Diffie, another student of Hellman's who says he was a hippie with "much more anti-societal views then," had not been scheduled to present a paper at the conference, but came up with one specifically to thumb his nose at the government's claims.