Accessing, navigating and browsing multimedia documents from a digital library should be as easy as reading and working with textbooks. However, common user interfaces for replay of multimedia data often assume a more passive, consuming attitude of the user. To be useful, techniques and features are required that allow more user interaction during replay of multimedia data, especially in a teac...

A typical computer user’s desktop contains large amount of formal data, such as addresses, events or bibliopraphies. Especially within a corporate or organizational environment, it is often important to exchange this data between employees. However, state-of-the-art communication technologies such as email or bulletin boards don’t allow to easily integrate desktop data in the communication proc...

A Note to the Reader These notes are based on a 2-week course that I taught for high school students at the Texas State Honors Summer Math Camp. All of the students in my class had taken elementary number theory at the camp, so I have assumed in these notes that readers are familiar with the integers mod n as well as the units mod n. Because one goal of this class was a complete understanding o...

We study combinatorial auctions where each item is sold separately but simultaneously via a second price auction. We ask whether it is possible to efficiently compute in this game a pure Nash equilibrium with social welfare close to the optimal one. We show that when the valuations of the bidders are submodular, in many interesting settings (e.g., constant number of bidders, budget additive bid...

We consider the class of max-min and min-max optimization problems subject to a global budget constraint. We undertake a systematic algorithmic and complexity-theoretic study of such problems, which we call problems design problems. Every optimization problem leads to a natural design problem. Our main result uses techniques of Freund-Schapire [FS99] from learning theory, and its generalization...

Digital libraries are frequently treated just as a new method of storage of digitized artifacts, with all consequences of transferring long-established ways of dealing with physical objects into the digital world. Such attitude improves availability, but often neglects other opportunities offered by global and immediate access, virtuality and linking — as easy as never before. The article prese...

The dependency pair approach is one of the most powerful techniques for automated (innermost) termination proofs of term rewrite systems (TRSs). For any TRS, it generates inequality constraints that have to be satisfied by well-founded orders. However, proving innermost termination is considerably easier than termination, since the constraints for innermost termination are a subset of those for...