Simplified Bid Languages – A Remedy to Efficiency Losses in Large Spectrum Auctions

Combinatorial auctions have been suggested as a mean to raise efficiency in multi-item negotiations with complementarities among goods as they can be found in procurement, energy markets, transportation, and the sale of spectrum auctions. Since 2008 the Combinatorial Clock Auction (CCA), a two-stage auction format has been used in many countries. [8] tested CCA in the lab and found out that the efficiency of CCA was relatively low, since bidders tended to submit too few bids. To reduce bidders’ complexity concerning evaluating lots of bundles, we simplified the bidding language without losing efficiency. Hereby, we used the knowledge of super-additivity and the fixed descending complementarity type of our value model. In lab experiments, we tested the two phases of the CCA auction, namely the Combinatorial Clock + (CC+) auction and a sealed bid version, with the simplification separately. Both formats yielded in higher efficiency and revenue than the CCA

Automated verification of UMLsec models for security requirements

Abstract. For model-based development to be a success in practice, it needs to have a convincing added-value associated with its use. Our goal is to provide such added-value by developing tool-support for the analysis of UML models against difficult system requirements. Towards this goal, we describe a UML verification framework supporting the construction of automated requirements analysis tools for UML diagrams. The framework is connected to industrial CASE tools using XMI and allows convenient access to this data and to the human user. As a particular example for usage of this framework, we present verification routines for verifying models of the security extension UMLsec of UML. These plug-ins should not only contribute towards usage of UMLsec in practice by offering automated analysis routines connected to popular CASE tools. The verification framework should also allow advanced users of the UMLsec approach to themselves implement verification routines for the constraints of self-defined stereotypes, in a way that allows them to concentrate on the verification logic. In particular, we focus on an analysis plug-in that utilises the model-checker Spin to verify security properties of UMLsec models which make use of cryptography (such as cryptographic protocols).

A Foundation for Tool-Supported Critical Systems Development with UML

High quality development of critical systems poses serious challenges. Formal methods have been proposed to address them, but their use in industry is not as wide-spread as originally hoped. We thus propose to use the Uni£ed Modeling Language (UML), the de-facto industry standard speci£cation language, as a notation together with a formally based tool-support for critical systems development. We introduce UML Machines, which is a formal notation designed to re¤ect properties of the UML execution semantics relevant to criticality requirements. We use it to de£ne a foundation that puts models for the different diagrams into context and gives a precise meaning to mechanisms such as message-passing between objects or components speci£ed in different diagrams, while offering the possibility to analyze criticality requirements. We present tool-support for this approach developed at the TU München, which facilitates transfer of the methodology to industrial contexts