Showing papers by "Helsinki Institute for Information Technology published in 2003"

Understanding contexts by being there: case studies in bodystorming

Abstract: A thorough appreciation of physical, social, interactional, and psychological contextual factors is crucial in the design of ubiquitous computing applications. This paper investigates the benefits of a method called bodystorming for carrying out design sessions in the original context, `in the wild', instead of the office. A location is selected that is identical or similar to the original environment. Innovation, carried out on-site, is based on ethnographical data presented as concrete design questions. Individual solutions to design questions are brainstormed and discussed on-site. Facets of data collection and preparation, formulation of design questions, selection of locations, session administration, and evaluation of design ideas are presented. We found that bodystorming permits immediate feedback for generated design ideas, and can provide a more accurate understanding of contextual factors. Bodystorming sessions were found memorable and inspiring. It is best suitable for designing for activities that are accessible and unfamiliar to the researchers.

UCPCD: user-centered product concept design

Abstract: Traditional user-centered methodologies have been developed for system-level and detailed-level design and not for concept-level design. This paper discusses thinking models and user-centered practices useful in the earliest phase of product developmentoproduct concept design.

Minimal k-Free Representations of Frequent Sets

Abstract: Due to the potentially immense amount of frequent sets that can be generated from transactional databases, recent studies have demonstrated the need for concise representations of all frequent sets. These studies resulted in several successful algorithms that only generate a lossless subset of the frequent sets. In this paper, we present a unifying framework encapsulating most known concise representations. Because of the deeper understanding of the different proposals thus obtained, we are able to provide new, provably more concise, representations. These theoretical results are supported by several experiments showing the practical applicability.

XML three-way merge as a reconciliation engine for mobile data

Abstract: Optimistic replication approaches are often employed on mobile devices, which raises the need for reconciliation of concurrently modified data. We propose that three-way merging algorithms, in particular those that are able to process tree-structured data in XML format, make good candidates for a generic data reconciliation engine on mobile devices.By exchanging data through XML files we impose minimal constraints on application design and are able to offer reconciliation services to a large number of existing applications. Reconciliation support can be added to an application in several increments, allowing application developers to choose a suitable level of support compared to implementation effort. We give two examples of reconciliation by three-way merging of XML.

Evaluating the role of a shared document-based annotation tool in learner-centered collaborative learning

Abstract: This study presents a shared document-based annotation tool, EDUCOSM. Usefulness of the system is empirically evaluated in a real-life collaborative learning context. Relationships between learner's self-rated use of learning strategies, cognitive outcomes, and completion of various tasks in the system are investigated. An empirical study (n=31) was conducted in order to investigate various dependencies between variables from precourse self-rated questionnaire, system log file data collected during the course and postcourse e-mail survey.

A Markov chain approach to reconstruction of long haplotypes.

Abstract: Haplotypes are important for association based gene mapping, but there are no practical laboratory methods for obtaining them directly from DNA samples. We propose simple Markov models for reconstruction of haplotypes for a given sample of multilocus genotypes. The models are aimed specifically for long marker maps, where linkage disequilibrium between markers may vary and be relatively weak. Such maps are ultimately used in chromosome or genome-wide association studies. Haplotype reconstruction with standard Markov chains is based on linkage disequilibrium (LD) between neighboring markers. Markov chains of higher order can capture LD in a neighborhood of a given size. We introduce a more flexible and robust model, MC-VL, which is based on a Markov chain of variable order. Experimental validation of the Markov chain methods on both a wide range of simulated data and real data shows that they clearly out perform previous methods on genetically long marker maps and are highly competitive with short maps, too. MC-VL performs well across different data sets and settings while avoiding the problem of manually choosing an appropriate order for the Markov chain, and it has low computational complexity.

Comparing SOAP Performance for Various Encodings, Protocols, and Connections

Abstract: SOAP is rapidly gaining popularity as the Web service protocol. At the same time, small mobile devices with wireless access, in particular to the Internet, are becoming more prevalent. At first look, it would seem that SOAP as a protocol consumes quite a lot of network bandwidth and processor time. Therefore its suitability for small devices and wireless links needs to be evaluated. This paper presents two optimizations that can be applied to typical uses of SOAP, message compression and persistent connections, and measures their performance in some common situations. Asynchronous messaging with SOAP is also treated briefly. The measurements indicate that a suitable compression scheme can save bandwidth substantially, and that the protocols underlying the typical use of SOAP can be improved considerably in the presence of unreliable high-latency networks.

Minimum Description Length Block Finder, a Method to Identify Haplotype Blocks and to Compare the Strength of Block Boundaries

Abstract: We describe a new probabilistic method for finding haplotype blocks that is based on the use of the minimum description length (MDL) principle. We give a rigorous definition of the quality of a segmentation of a genomic region into blocks and describe a dynamic programming algorithm for finding the optimal segmentation with respect to this measure. We also describe a method for finding the probability of a block boundary for each pair of adjacent markers: this gives a tool for evaluating the significance of each block boundary. We have applied the method to the published data of Daly and colleagues. The results expose some problems that exist in the current methods for the evaluation of the significance of predicted block boundaries. Our method, MDL block finder, can be used to compare block borders in different sample sets, and we demonstrate this by applying the MDL-based method to define the block structure in chromosomes from population isolates.

Transaction management for m-commerce at a mobile terminal

Abstract: Although there has been a lot of discussion of "transactions" in mobile e-commerce (m-commerce), very little attention has been paid for distributed transactional properties of the computations facilitating m-commerce. In this paper, we first present a requirement analysis and then present a wireless terminal-based transaction manager (TM) architecture. This architecture is based on the assumption that there is an application that supports certain business transaction(s) and that it uses the TM to store transactional state information and retrieve it after a communication link, application, or terminal crash. We present the design of such a TM, including the application interface, modules and log structure. A pilot implementation of this TM for the location-based application is also discussed. We further discuss other alternatives to design such a TM that together can be called "ontological transaction monitor". This acts as an intelligent component between the application and the servers accessed during m-commerce transactions and controls the perceivable communication behavior of the terminal towards the servers, maintains the state information and takes care of tight coupling of transactional properties of the computations as well as of security and privacy.

EDUCOSM - personalized writable Web for learning communities

Abstract: Many of the possibilities of Web-based education are still unexplored. It seems that novel ways of thinking about both learning and technology are needed to get beyond the limitations of the traditional classroom setting. In this paper we introduce EDUCOSM, which focusses on the possibilities of collaboration and the open-ended nature of the Web. Its main features include sharing and annotation of arbitrary Web-pages, and an adaptive desktop for accessing the evolving contents of the system. EDUCOSM has been used in a real Web-based course, and the experiences are discussed along with a description of the tool. Although the approach requires both the teacher and the students to rethink their roles, the feedback received so far has been encouraging.

When discriminative learning of Bayesian network parameters is easy

Abstract: Bayesian network models are widely used for discriminative prediction tasks such as classification. Usually their parameters are determined using 'unsupervised' methods such as maximization of the joint likelihood. The reason is often that it is unclear how to find the parameters maximizing the conditional (supervised) likelihood. We show how the discriminative learning problem can be solved efficiently for a large class of Bayesian network models, including the Naive Bayes (NB) and tree-augmented Naive Bayes (TAN) models. We do this by showing that under a certain general condition on the network structure, the discriminative learning problem is exactly equivalent to logistic regression with unconstrained convex parameter spaces. Hitherto this was known only for Naive Bayes models. Since logistic regression models have a concave log-likelihood surface, the global maximum can be easily found by local optimization methods.

Complexity of simple nonlogarithmic loss functions

Abstract: The loss complexity for nonlogarithmic loss functions is defined analogously to the stochastic complexity for logarithmic loss functions such that its mean provides an achievable lower bound for estimation, the mean taken with respect to the worst case data generating distribution. The loss complexity also provides a lower bound for the worst case mean prediction error for all predictors. For the important /spl alpha/-loss functions |y-/spl circ/y|/sup /spl alpha//, where y-y/spl circ/ denotes the prediction or fitting error and /spl alpha/ is in the interval, an accurate asymptotic formula for the loss complexity is given.

Adaptive Agent-based Service Composition for Wireless Terminals

Abstract: Software agents are one of the building blocks of ambient intelligence and pervasive computing. Adaptation to changes in the execution context is necessary in order to provide continuous and smooth provision of services for wireless clients. In this paper, we present a system for adapting a service consisting of multiple agents based on application, terminal and communication models and profiles. The system adapts and composes the service by finding the best combination of local and external agents to contact. The context models are based on experimentation with actual devices and environments. We present a theoretical cost model for runtime service composition, and examine experimental results that are based on an example scenario.

Client mobility in rendezvous-notify

Abstract: Event-based computing is vital for the next generation mobile services and applications that need to meet user requirements irrespective of time and location The event paradigm is a form of asynchronous one-to-many communication and allows clients to receive information that matches their interests through filtering Event-based communication is a good candidate for mobile computing, because it is asynchronous and supports disconnected operation However, user and terminal mobility present problems pertaining to synchronization and delivery that need to be solved In this paper, we examine and analyze mobility in the Rendezvous-Notify architecture This event-delivery architecture is based on two server roles: access servers that maintain subscription information and buffered events, and resolution servers that are responsible for event channels and routing events to access servers Access to event channels is done using a rendezvous mechanism

Joint Annotation and Knowledge Building in Collaborative E-Learning

Abstract: Tools to enable joint annotation help in collaborative knowledge building in elearning. EDUCOSM is a system that offers two types of annotation, namely highlights and comments, on any Web-page that are visible to other learners immediately. The tool is built to enable straightforward interaction between the students and the material. Empirical data suggests that the concept of joint annotation can help in processing large amount of material by a large number of students.

Designing personalized user experiences for eCommerce: theory, methods, and research

Abstract: The present workshop aims to form a community of individuals interested in exploring the user implications of personalized eCommerce applications. People working in industry, academia, and government are welcomed to participate. The aim of the two-day workshop is to access the current state of theory, methods, and research in this area and to create a theoretical framework on personalization of the user experience in eCommerce to help identify critical questions and guide future research.

Deciding Termination of Query Evaluation in Transitive-Closure Logics for Constraint Databases

Abstract: We study extensions of first-order logic over the reals with different types of transitive-closure operators as query languages for constraint databases that can be described by Boolean combinations of polynomial inequalities over the reals. We are in particular interested in deciding the termination of the evaluation of queries expressible in these transitive-closure logics. It turns out that termination is undecidable in general. However, we show that the termination of the transitive closure of a continuous function graph in the two-dimensional plane, viewed as a binary relation over the reals, is decidable, and even expressible in first-order logic over the reals. Based on this result, we identify a particular transitive-closure logic for which termination of query evaluation is decidable and which is more expressive than first-order logic over the reals. Furthermore, we can define a guarded fragment in which exactly the terminating queries of this language are expressible.

Expressing the box cone radius in the relational calculus with real polynomial constraints

Abstract: We show that there is a query expressible in first-order logic over the reals that returns, on any given semi-algebraic set A, for every point, a radius around which A is conical in every small enough box. We obtain this result by combining results from differential topology and real algebraic geometry, with recent algorithmic results by Rannou.

The Role of Inservice Teachers’ Motivation, Learning Strategy and Social Ability Profiles in a CSCL Environment

Abstract: The process of employing Finnish inservice teacher’s (N=54) self-rated motivation, learning strategy, and social ability profile into collaborative learning tasks of an on-line learning environment was investigated The profile information obtained from a 34-item questionnaire was stored into a system consisting of a set of asynchronous collaborative knowledge constructing tools Learners were expected to form a group of two, and annotate by highlighting and commenting an on-line document The preliminary results show that annotation quality in the learning tasks was rated low on those students who like practical instructions from teacher Annotation quality was rated high on those students who are interested in the course topic and generally prefer to study demanding subjects from which they can learn something new Both self-made highlightings and comments were experienced to be more useful for the learning process than those made by other learners Preliminary results of the e-mail survey indicated that all the respondents strongly agreed when asked if the system brought added value to their learning processes

The Impact of Free and Open Source Components for Competition in Microcomputer Operating System Software Markets

Abstract: This paper describes the impact of different open source copyright licensing arrangements to the competition in microcomputer operating system markets. We compare the historical evolution of the licensing policies of Microsoft Windows, Apple OS X and GNU/Linux operating systems. We argue that open source and free software licensing has been one of the most important changing factors in the microcomputer operating system markets in the recent years. We have seen both new entrants in the relatively closed markets and renewed business models by incumbents. However, there has been no single open source strategy but merely all market players have adopted open source into their operating system strategy in one form or other.