The emergence of the web service market in the last years offers more and more the opportunity for companies to buy web services from external service providers as an alternative to develop them internally. Such considerations are well-known in IS literature and discussed in the context of IT outsourcing and make-orbuy decision making regarding IT applications. However, characteristics of web s...

COMMUNICATIONS OF THE ACM March 1999/Vol. 42, No. 3 81 However, the potential of the Internet for transforming commerce is largely unrealized. Electronic purchases are still largely nonautomated. While information about products and vendors is more easily accessible, and orders and payments are dealt with electronically, humans are still in the loop in all stages of the buying process, adding t...

In this work, we show that for linear upper triangular systems of differential equations, we can use the diagonal entries to obtain the Sacker and Sell, or Exponential Dichotomy, and also –under some restrictions– the Lyapunov spectral intervals. Since any bounded and continuous coeficient matrix function can be smoothly transformed to an upper triangular matrix function, our results imply that...

The emergence of the web service market has enabled firms to choose between developing web services internally and purchasing them externally from web service providers. In general, these socalled make-or-buy decisions have been the object of intense debate in the IT outsourcing literature. However, characteristics of web services such as loose coupling and the current trend of digitalizing app...

One prominent feature of information goods is that they have large fixed costs of production, and small variable costs of reproduction. Cost-based pricing makes little sense in this context; value-based pricing is much more appropriate. Different consumers may have radically different values for a particular information good, so techniques for differential pricing become very important. There a...

The emergence of the web service market in the last years offers more and more the opportunity for companies to buy web services from external service providers as an alternative to develop them internally. Such considerations are well-known in IS literature and discussed in the context of IT outsourcing and make-orbuy decision making regarding IT applications. However, characteristics of web s...

A trading strategy is an algorithm that provides decision support for a trader. An ideal system suggests which stocks to buy and sell at every moment. Limited but still very useful trading strategies suggest stocks to buy, but leave the sell decisions and the decision of proportions of different stocks to the trader, or to another automatic decision mechanisim. In this paper we use a previously...

BACKGROUND It is often claimed that a regulated kidney market would significantly reduce the kidney shortage, thus saving or improving many lives. Data are lacking, however, on how many people would consider selling a kidney in such a market. METHODS A survey instrument, developed to assess behavioural dispositions to and attitudes about a hypothetical regulated kidney market, was given to Sw...

HyLL (Hybrid Linear Logic) and SELL (Subexponential Linear Logic) are logical frameworks that have been extensively used for specifying systems that exhibit modalities such as temporal or spatial ones. Both frameworks have linear logic (LL) as a common ground and they admit (cut-free) complete focused proof systems. The difference relies on the way modalities are handled. In HyLL, truth judgmen...