CIKM WORKSHOP REPORT

Report on the Fourth Workshop on Locationand the Web (LocWeb 2014)
Dirk Ahlers1 , Erik Wilde2 , and Bruno Martins3
1

NTNU – Norwegian University of Science and Technology, Trondheim, Norway,
dirk.ahlers@idi.ntnu.no2
Siemens, Berkeley, USA, dret@berkeley.edu
3
ULisboa, IST and INESC-ID, Lisbon, Portugal, bruno.g.martins@ist.utl.pt

Abstract
Location is a major aspect behind many approaches in Information Retrieval, naturally
appearing in diverse forms and as a cross-cutting topic. To give the location topic an adequate venue, LocWeb 2014 restarted a workshop series at the intersection of geospatial search,
information management, and Web architecture, with a main focus on location-aware information access. LocWeb has in the past been a ‘travelling’ workshop, gathering views fromdifferent communities, but always centered on the topic of location. As previously, contributions to the workshop reflected a multitude of fields that demand and use location featuresand geospatial information, and LocWeb 2014 featured presentations that look at the topicof location on the Web from an interdisciplinary perspective. Reflecting this interdisciplinarity, LocWeb 2014 consisted of an interesting variety of contributions from a range of topics:
one keynote, four long and two short papers, and a discussion session. This report gives anoverview of the workshop and summarizes its major contributions.

1Introduction

Location has quickly moved from the next hot thing into being accepted as an important
aspect of the Web and, especially, the mobile Web. Its importance is growing even more,as mobile access is surpassing other forms of Web usage and many players adopt a mobilefirst strategy. Location also plays a role in the form of the explicit or implicit location ofresources, locations described in content, location of users, location APIs, or mobile apps,also being used in geospatial-aware data mining or large-scale analytics. Location is thus astrong driver behind many recent innovations and research activities.
LocWeb, the Workshop on Location and the Web, has taken up location as its main
topic, understanding it as a cross-cutting issue. LocWeb has been a ‘travelling’ workshop,
having been held before at venues as diverse as WWW, CHI, and IoT. Following up on thisbackground, the main objective of the workshop was to bring together a community of researchers at the intersection of location and the Web, for exchanging ideas and discussing andACM SIGIR Forum35Vol. 49 No. 1 June 2015

developing the role of location. LocWeb 2014 took place on November 3rd 2014 in Shanghai,
China, co-located with CIKM 2014, the 23rd ACM International Conference on Informationand Knowledge Management, which was held at the Shanghai Regal International East Asia
Hotel at coordinates 31.2018N, 121.4440E.
The LocWeb workshop series is aimed at establishing an integrated venue where thelocation aspect can be discussed in depth within an interested community. LocWeb follows
the main theme of Location-Aware Information Access, with subtopics related to Search,Analytics, Mobility, Apps, Services, and Systems. The workshop is thus designed to reflect
the multitude of fields that demand and utilize location features from an interdisciplinary
perspective.
A short workshop introduction was available as a preparation for CIKM attendees [2]; wenow aim to give a detailed report of the full workshop including its keynote and discussion
session. Further details, including most of the presentations made at the workshop andprevious editions, can be found on the workshop homepage1 .

2Workshop Theme and Topics

LocWeb addresses the subject of location as a cross-cutting issue in Web research and technology, consequently examining location aspects in the domains of search, analytics, mobility,apps, services, and systems. Through LocWeb, we hope to further the integration of thegeospatial dimension into the Web, by promoting research on the topic.
Our general aim is to establish a topic-specific venue where researchers from different
fields and backgrounds, be it data mining, recommendation, search, systems, social media,applications, or standards, can discuss and develop the role of location. This can hopefully
aid researchers in identifying common issues of geospatial information management acrossdifferent fields and from different perspectives, and in learning about new approaches.
The main topics of interest, as announced in the call for papers for LocWeb 2014,
are: Location-Aware Information Access, Geospatial Web Search, Location-Based Services,
Geospatial Web Analytics, Geospatial Visual Analytics, Location-Aware Data Mining, Location-Aware Text Processing, Location-Based Entity Retrieval, Conflation, Merging, Integration, Location-Based Recommendation, Place Semantics, Lifecycle of Location Data, Modeling Location, Geo-Social Media and Systems, Location-Based Social Networks, Geo-Crowdsourcing, Map-Based Interfaces and Geospatial HCIR, Geospatial Applications, Geospatial
Awareness, Mobile Search and Recommendation, Mobile Apps and Mobile Context, MobilityData, Location-Aware Web-Scale Systems, Large Ecosystems, and Location Standards.

3Keynote

After a short introduction given by the organizers, the workshop started with a keynoteby Vanessa Murdock from Microsoft, titled Two Ways of Thinking About Where People
Go [8]. We partly paraphrase from her abstract. The keynote reflected on how classicalstudies in human mobility can still inspire current and highly-innovative research, particularly
focusing on Ravenstein’s Gravitational Model from 1885 [10] and on Stouffer’s Intervening
Opportunities Model from 1940 [11].
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http://dhere.de/locweb2014/

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Both these authors wrote at a time when people were beginning to be mobile and affluent,a trend which nowadays continues in a way that they could not have imagined. They proposed
contrasting models to explain human mobility, which are as fresh and relevant today as in
the day they were originally published, due to the vast amount of data people are nowadays
volunteering about where they go in their daily lives. There is an interesting aspect of
granularity in the work, which was used to explain large migratory movements from rural
to urban areas, yet it is general enough that it can also be applied to individual users andtheir local movements within a city. Vanessa Murdock presented her reflections on how
these two models relate to recent work on the subject of local search and point of interest
recommendation, arguing that the models naturally correspond to different reasons to whysome particular places might be considered as more relevant than others (i.e., places may beconsidered as relevant because they possess specific properties, and their relevance is likely todecrease according to geospatial distance towards the user, and also according to the numberof other relevant places that are located nearby). She argues that there is a spectrum of places
ranging from merely convenient to very special. Following, the question of what makes places
special to particular individuals assumes a key importance in the context of future directions
for research in the area of local search.
In her presentation, she also highlighted particular engineering challenges related to data
quality and large-scale information integration, given that the resources that are currently
supporting Web-scale location-based services often result from the consolidation of multiple sources of heterogeneous data. Exemplarily, she demonstrated the difficulty of location
detection in social media by an experiment with two native english speakers from different countries who could only reach an inter-assessor agreement of about 74% on location
detection. These and other observations also fueled the discussion session.

4Paper Presentations

The workshop accepted 6 papers, which were arranged in two sessions of two long and one
short paper each. We had, on average, 3.125 reviews per paper and the overall acceptance
rate was 75%. We had author groups from all over the world, namely from Australia,
Germany, Japan, Taiwan, and the US. There were no cross-country authorships. Full papers
had 25 minutes of presentation and 10 minutes time for discussion, while short papers werepresented for 15 minutes with 5 minutes for questions, to make the workshop more interactive
and facilitate discussion. The proceedings [1] are available in the ACM Digital Library2 .
The first session was titled Indexing and Interfaces, showing the first part of the broad
range of topics that are currently dealing with location.
The first paper, titled Hybrid Quantized Resource Descriptions for Geospatial Source Selection and authored by Kufer and Henrich, took on the issue of representing geotagged
media collections in peer-to-peer networks, so as to make them efficiently searchable. Thechallenge is to describe the geospatial footprint of media collections stored on one peer in
a compact way, this way making querying within the distributed system efficient by selecting only promising sources. The authors proposed a hybrid approach that optimizes both
selectivity and representation size to support the selection of those peers that potentiallycarry relevant results [5]. This work was also presented as a demo showcasing the differentapproaches that were implemented.
2

http://dl.acm.org/citation.cfm?id=2663713

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In Considering Common Data Model for Indoor Location-aware Services, Niu, Matsumoto, Saiki, and Nakamura describe their work towards the formal definition of data
models for indoor positioning, abstracting from different implementations of indoor positioning systems to allow for easier generation of location-based services. This work aimed
to achieve a looser coupling of components, and the authors have the long-term goal ofestablishing a more standardized way to model indoor locations and their relations [9].
In a short paper by Tytyk and Baldwin titled Automatic Zoom Level Prediction forInformal Location Descriptions, the authors considered the automatic selection of appropriate
zoom levels in map interfaces, when presented with informal location descriptions. They
presented a classification approach that uses multiple features of geospatial descriptions,evaluating it on different levels of noisy data [12].
The second paper session was titled Processing and Understanding, and formed the second
half of the technical programme.
In Automatic Identification of Locative Expressions from Social Media Text: A Comparative Analysis, Liu, Vasardani, and Baldwin presented a comparative analysis over various
geoparsers in the task of identifying locative expressions, benchmarking their performanceon examples of the informal language that is commonly found in status updates in socialnetworks. The obtained results indicate that, on informal content, the geoparsing accuracy
is decidedly lower that what one would expect from the analysis of previous work on thearea. The authors also discussed and analyze in detail the observed errors, as well as theprocess taken for the construction of the corpus supporting their experiments [7].
Chang, Fan, and Chen, in a paper titled On the Semantic Annotation of Daily Places: A
Machine-Learning Approach, reported on the use of learning-based classification approaches
to understand human movement data, inferring place semantics of visited locations based on
temporal patterns associated to the location tracking of participants in a field study [3].
Finally, the short paper titled HMM-based Address Parsing with Massive Synthetic Training Data Generation, by Li, Kardes, Wang, and Sun, reported on the use of Hidden Markov
Models to parse and segment addresses into their multiple components and exploring ways togenerate training data along the way. This was a rare issue where the original data was too
clean and training data had to be derived to add noise. Their system is used in a similarity
function for record linkage [6].

5Discussion Session

The discussion session was designed to uncover open issues in the field and lay a foundation
for future work. Authors were asked to provide an overview of the open issues in their own
work and bring it to the workshop as a starting point. The discussion showed a number ofissues, some of which were of course focused on the individual work, and also yielded a fairnumber of general issues and themes.
The work presented at the workshop brings together a representative broad list of application scenarios. These include local search, indexing, location models, user support,geoparsing, and trajectories and place annotation.
The general discussions at the workshop show that there are major cultural, language, andgeographical differences that have to be addressed within the location topic. For example,
there is not yet a reliable unified geoparser available that would work both for broad placereferences and precise addresses in all countries. Individual research efforts happen for various

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regions but are not yet integrated. On the other hand, commercial providers and searchengines have developed their own address parsers for local search, but they are of unknown
quality, with the perceived quality closely related to the perceived importance of regions toindustry. This is closely related to imbalanced resources and tools for various regions are otherbiases, mostly population bias and technology bias, where populated regions and regions
populated by technology-savvy people tend to be overrepresented in many datasources, notonly in user-generated data or social media. Geoparsing and georeferencing is also an ongoing
topic in TREC or the GIR workshop series [4]. We also saw that the location topic can benefit
from a strong connection between different communities and for the future, also a stronger
connection to W3C activities.
While we are dealing quite often with simple point-based locations, there are insufficient
data models for larger places, unclear semantics of what exactly is located at the coordinatesor how they were derived. In short, many places have an unknown extent, which is an issue
of unknown granularity. We also see some concern towards the use of relative versus absolute
positioning and a stronger demand towards location normalisation and standardisation.
One thing that we found confirmed in the papers and the discussion is the need forthorough work on error analysis and descriptions of limitations of current methods andtools. We encourage everyone working on these issues to embrace them as a good way tolearn and to move the field forward.

6Conclusion and Future Directions

The 2014 Workshop on Location and the Web had its main focus on location-aware information access. The workshop featured an interesting variety of contributions, with one keynote,four long papers, two short papers, and a final discussion session. Presenters and attendees,
both from industry and academia, debated current important aspects in the field, as well as
open issues and future research directions. Overall, we have seen a lot of interesting open
issues. Few of them are easy, most are actually very challenging. It will be our pleasure tocontinue to work on them in the future.
The next edition of LocWeb, The 5th International Workshop on Location and the Web3 ,will be held in May 2015 at the 24th World Wide Web Conference, in Florence, Italy.

Acknowledgements
We would like to thank the authors of submitted papers for their efforts, and all attendees
for making LocWeb 2014 an interesting, interactive and diverse workshop. A special thanks
goes to Vanessa Murdock, for giving a very inspiring keynote. Our thanks especially include
the members of the program committee for their work in reviewing the contributions:
Susanne Boll, University of Oldenburg, Germany; Keith Cheverst, Lancaster University,UK; Karen Church, Yahoo! Research, USA; Max Egenhofer, University of Maine, USA; Claudia Hauff, Delft University, Netherlands; Andreas Henrich, University of Bamberg, Germany;
Christopher Jones, Cardiff University, UK; Eric Kansa, Alexandria Archive Institute, USA;
Carsten Kessler, CUNY, USA; Mareike Kritzler, Siemens, USA; Chandan Kumar, OFFIS,Germany; Vanessa Murdock, Bing, USA; Kjetil Nørvåg, NTNU, Norway; Clodoveu Davis3

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Jr., Federal University of Minas Gerais, Brazil; Adrian Popescu, CEA LIST, France; RossPurves, Universität Zürich, Switzerland; Daniele Quercia, Yahoo!Labs, Barcelona, Spain;
Martin Raubal, ETH Zürich, Switzerland; Massimiliano Ruocco, NTNU, Norway; Johannes
Schöning, Hasselt University, Belgium; Steven Schockaert, Cardiff University; Rainer Simon, AIT Austrian Institute for Technology; Arjen de Vries, CWI, Netherlands; Xing Xie,Microsoft Research Asia, China.
We are also grateful to the organizers of CIKM for hosting the workshop and to ACMand Sheridan for their support. Dirk Ahlers would like to thank the ERCIM Fellowship
Program and the NTNU IDI travel fund for support. Bruno Martins acknowledges the financial support from FCT, through project grants with references EXPL/EEI-ESS/0427/2013(KD-LBSN), EXCL/EEI-ESS/0257/2012 (DATASTORM) and PEst-OE/EEI/LA0021/2013(INESC-ID’s multi-annual funding).

References[1] D. Ahlers, E. Wilde, and B. Martins, editors. LocWeb ’14: Proceedings of the 4thInternational Workshop on Location and the Web, CIKM 2014, New York, NY, USA,2014. ACM.
[2] D. Ahlers, E. Wilde, and B. Martins. LocWeb’14 – 4th International Workshop onLocation and the Web: CIKM 2014 Workshop Summary. In Proceedings of the 23rd
ACM International Conference on Information and Knowledge Management, New York,NY, USA, 2014. ACM.
[3] C.-W. Chang, Y.-C. Fan, and A. Chen. On the Semantic Annotation of Daily Places:
A Machine-Learning Approach. In [1].
[4] C. B. Jones and R. S. Purves. GIR’13 Workshop Report: 7th ACM SIGSPATIAL Workshop on Geographic Information Retrieval. SIGSPATIAL Special, 6(1):14–14, 2014.
[5] S. Kufer and A. Henrich. Hybrid Quantized Resource Descriptions for Geospatial Source
Selection. In [1].
[6] X. Li, H. Kardes, X. Wang, and A. Sun. HMM-based Address Parsing with Massive
Synthetic Training Data Generation. In [1]. Short Paper.
[7] F. Liu, M. Vasardani, and T. Baldwin. Automatic Identification of Locative Expressions
from Social Media Text: A Comparative Analysis. In [1].
[8] V. Murdock. Two ways of thinking about where people go. In [1]. Keynote.
[9] L. Niu, S. Matsumoto, S. Saiki, and M. Nakamura. Considering Common Data Modelfor Indoor Location-aware Services. In [1].
[10] E. G. Ravenstein. The Laws of Migration. Journal of the Statistical Society of London,48(2), 1885.
[11] S. A. Stouffer. Intervening Opportunities: A Theory Relating Mobility and Distance.
American Sociological Review, 5(6), 1940.
[12] I. Tytyk and T. Baldwin. Automatic Zoom Level Prediction for Informal Location
Descriptions. In [1]. Short Paper.

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