A Hill-Climbing Approach for Optimizing Classification Trees Xiaorong Sun, Steve Y. Chiu and Louis Anthony Cox U S WEST Advanced Technology Boulder, CO 80303, USA

We consider the problem of minimizing the expected cost of determining the correct value of a binary-valued function when it is costly to inspect the values of its arguments. This type of problem arises in distributed computing, in the design of diagnostic expert systems, in reliability analysis of multi-component systems, and in many other applications. Any feasible solution to the problem can be described by a sequential inspection procedure which is usually represented by a binary classification tree. In this paper, we propose an efficient hill-climbing algorithm to search for the optimal or near-optimal classification trees. Computational results show that the hill-climbing approach was able to find optimal solutions for 95% of the cases tested. 11.1 Introduction The following minimum expected-cost classification problem arises in many logical inference, reliability testing, pattern recognition, and statistical classification applications. Suppose that X = (x 1 ; \Delta \Delta \De..

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Modern work is highly communication-centric. Research shows the critical role that communication applications- in particular email- play in everyday work. Email is used to organize and delegate tasks, to manage communications, as an archival repository for work documents and as a contact manager (Bellotti et al., 2005, Duchenaut and Bellotti, 2001, Whittaker, 2005, Whittaker and Sidner, 1996). However, there are numerous problems using email for task management (Bellotti et al., 2005, Whittaker et al., 2002, Whittaker, 2005). Users relying on email complain about: • forgetting commitments from self and others (tasks that they ‘owe ’ or are ‘owed’) • tracking global task status (it’s hard to abstract from multiple messages to determine where a project currently stands) • determining who’s involved in a complex task • integrating information across different technologies (people may communication about a task in email, voicemail or using IM – and it’s often hard to combine information) • managing attachments. Partly because of these problems, there have been various attempts made to develop alternative models and technologies for collaboration. The most significant of these are shared workspaces such as TeamRooms and more recently Wikis. The defining feature of these technologies is that they support collaboration using a Shared Representation- which provides the structure into which participants can publish their contributions, or organize collections of objects. Let us consider a system that addresses activity management by providing a shared representation of activities