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Institution

Helsinki Institute for Information Technology

FacilityEspoo, Finland
About: Helsinki Institute for Information Technology is a facility organization based out in Espoo, Finland. It is known for research contribution in the topics: Population & Bayesian network. The organization has 630 authors who have published 1962 publications receiving 63426 citations.


Papers
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Book ChapterDOI
10 Sep 2012
TL;DR: This work introduces a distributed algorithm that has a novel time---space tradeoff and, in practice, achieves a significant reduction in both memory and time compared to state-of-the-art methods.
Abstract: The goal of frequency constrained string mining is to extract substrings that discriminate two (or more) datasets. Known solutions to the problem range from an optimal time algorithm to different time---space tradeoffs. However, all of the existing algorithms have been designed to be run in a sequential manner and require that the whole input fits the main memory. Due to these limitations, the existing algorithms are practical only up to a few gigabytes of input. We introduce a distributed algorithm that has a novel time---space tradeoff and, in practice, achieves a significant reduction in both memory and time compared to state-of-the-art methods. To demonstrate the feasibility of the new algorithm, our study includes comprehensive tests on large-scale metagenomics data. We also study the cost of renting the required infrastructure from, e.g. Amazon EC2. Our distributed algorithm is shown to be practical on terabyte-scale inputs and affordable on rented infrastructure.

14 citations

Proceedings ArticleDOI
25 Jun 2007
TL;DR: An overview of the arguments in favor of a binary format in scientific computing, of work done in this area by the W3C, and some benchmarks comparing XML with various processing techniques available with binary formats are provided.
Abstract: XML is a widely-used technology for interoperable data representation, and its scope of usage has widened even more in recent years. However, this expansion of XML's application areas has identified limitations and inefficiencies that seem inherent in XML due to its verbosity and redundancy. Because of this, various industry groups and standardization organizations have undertaken to define alternate representations of XML data to better address their needs while still retaining compatibility with XML. This paper provides an overview of the arguments in favor of a binary format in scientific computing, of work done in this area by the W3C, and some benchmarks comparing XML with various processing techniques available with binary formats.

14 citations

Journal ArticleDOI
TL;DR: A user-centric approach was chosen to develop a "hybrid book", a combination of a traditional schoolbook and a mobile phone, which facilitated utilization of the digital content both inside and outside the classroom.
Abstract: Printed and digital learning materials are usually developed separately. Therefore, little notice has been given to the possibilities of combining the two. This study introduces a new concept that combines printed and digital materials. A user-centric approach was chosen to develop a "hybrid book", a combination of a traditional schoolbook and a mobile phone. Learning materials were combined into one entity by enabling access to the digital material through images in the book. The user groups of interest were 11-and 12-year-old pupils, their teachers, and parents. The concept was tested with materials for English as a foreign language EFL. After a human-centred design process, the final application was given to one class for actual use and evaluation for a period of three weeks. Many potential benefits of using mobile phones for learning purposes were recognized, as they facilitated utilization of the digital content both inside and outside the classroom.

14 citations

Journal ArticleDOI
TL;DR: Analysis of data collected in two FIA World Rally Championships events asks how it is possible for a control center that is seemingly so “ad hoc” in nature to achieve a remarkable safety level in the face of many safety-critical incidents.
Abstract: Control centers in large-scale events entail heterogeneous combinations of off-the-shelf and proprietary systems built into ordinary rooms, and in this respect they place themselves in an interesting contrast to more permanent control rooms with custom-made systems and a large number of operational procedures. In this article we ask how it is possible for a control center that is seemingly so “ad hoc” in nature to achieve a remarkable safety level in the face of many safety-critical incidents. We present analyses of data collected in two FIA World Rally Championships events. The results highlight three aspects of the workers' practices: (a) the practice of making use of redundancy in technologically mediated representations, (b) the practice of updating the intersubjective understanding of the incident status through verbal coordination, and (c) the practice of reacting immediately to emergency messages even without a comprehensive view of the situation, and gradually iterating one's hypothesis to correct...

14 citations

Journal ArticleDOI
TL;DR: This work presents an algorithm for testing connectedness of large implicit graphs and brings forward a benchmark instance for such algorithms.
Abstract: Switching is a local transformation that when applied to a combinatorial object gives another object with the same parameters. It is here shown that the cycle switching graph of the 11 084 874 829 isomorphism classes of Steiner triple systems of order 19 as well as the cycle switching graph of the 1 348 410 350 618 155 344 199 680 000 labeled such designs are connected. In addition to giving an understanding of the multitude of Steiner triple systems—at least for order 19 but perhaps also generally—this work also presents an algorithm for testing connectedness of large implicit graphs and brings forward a benchmark instance for such algorithms.

14 citations


Authors

Showing all 632 results

NameH-indexPapersCitations
Dimitri P. Bertsekas9433285939
Olli Kallioniemi9035342021
Heikki Mannila7229526500
Jukka Corander6641117220
Jaakko Kangasjärvi6214617096
Aapo Hyvärinen6130144146
Samuel Kaski5852214180
Nadarajah Asokan5832711947
Aristides Gionis5829219300
Hannu Toivonen5619219316
Nicola Zamboni5312811397
Jorma Rissanen5215122720
Tero Aittokallio522718689
Juha Veijola5226119588
Juho Hamari5117616631
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
20231
20224
202185
202097
2019140
2018127