Differences

This shows you the differences between two versions of the page.

--- teaching:mfe:is [2014/03/25 12:51]
svsummer [Foundations of Data Description Languages]
+++ teaching:mfe:is [2016/04/14 08:34]
svsummer
@@ Line 1: / Line 1: @@
-====== MFE 2014-2015 : Web and Information Systems ======
+====== MFE 2016-2017 : Web and Information Systems ======
 ===== Introduction =====
@@ Line 16: / Line 16: @@
 <note>Please note that this list of subjects is **not exhaustive. Interested students are invited to propose original subjects.**</note>
-===== Automatic detection of name variations =====
+===== Master Thesis in Collaboration with Euranova =====
-Toon Calders (WIT)
-For this project a large data collection consisting of historical birth, death, and marriage certificates of the province of North-Brabant in the Netherlands is available. This collection contains certificates for about 3 million people, from 1580 until 1955. This collection of paper documents has been indexed by volunteers. For many of the certificates (unfortunately the index is not complete yet), the names of the people involved in it, and their role have been recorded in a database. Consider for instance the following example of an index entry for a death certificate:
+Our laboratory performs collaborative research with Euranova R&D (http://euranova.eu/). The list of subjects proposed for this year by Euranova can be found
+{{:teaching:mfe:master_thesis_euranova_2015.pdf|here}}
-^ Death certificate ^^
+These subject include topics on distributed graph processing, processing big data using Map/Reduce, cloud computing, and social networks.
-|Deceased	|Johanna Louise Fredrika Frans |
-|Relation of the deceased |Gerard Cornelius Reincke de Sitter |
-|Father of the deceased	|Carl Ludwig Frans |
-|Mother of the deceased	|Alida Philippina Zehender |
-|Type of deed |death certificate |
-|Number of deed	|5 |
-|Place	|Beers |
-|Date of decease |26-02-1825 |
-|Period	|1825 |
-|Contains |Overlijdensregister 1825 |
-|Number of inventory |50 |
-|Record number	|456 |
-There are, however, several problems with the data recorded by the volunteers:
+  * Contact : [[ezimanyi@ulb.ac.be|Esteban Zimanyi]]
-  - Volunteers made mistakes when recording the names
-  - Natural name variations occur; for instance, during the Napoleonic era, Willem preferred to be called Guillaume. After the French left the Netherlands, Willem became Willem again. Other, less spectacular variations: Fredrika versus Frederika.
-  - Another source of variation is the granularity at which locations are reported. Sometimes locations have been reported at suburb or even neighborhood level, whereas in other records only the city is reported.
-  - Also the original data contained errors. For instance, the order of names may have been swapped.
-The goal of this graduation project is to automatically detect name variations for location and person names, using statistical and data mining methods. Because of the large size of the database it is very likely that most name variations occur frequently. In a pilot study, it was shown that name variations could be detected by finding pairs of full names sharing most surnames, but not all. The differences often were name variations. Your task will be to extend this approach to also include locations, and exploit additional background knowledge such as: for most birth certificates there is a matching death certificate, no one has more than one birth and death certificate, etc.
+===== Complex Event Processing in Apache Spark and Apache Storm =====
-This project has a large research component, so your creative input will be required as well. For this project it is absolutely not necessary to speak or understand Dutch.
-Interested? Contact [[toon.calders@ulb.ac.be|Toon Calders]]
+The master thesis is put forward in the context of the SPICES "Scalable Processing and mIning of Complex Events for Security-analytics" research project, funded by Innoviris.
-===== Analyzing state-of-the-art technology for handwritten text recognition in a practical case study =====
+Within this project, our lab is developping a declarative language for Complex Event Processing (CEP for short). The goal in Complex Event Processing is to derive pre-defined patterns in a stream of raw events. Raw events are typically sensor readings (such as "password incorrect for user X trying to log in on machine Y" or "file transfer from machine X to machine Y"). The goal of CEP is then to correlate these events into complex events. For example, repeated failed login attempts by X to Y should trigger a complex event "password cracking warning" that refers to all failed login attempts.
-Toon Calders (WIT) and Olivier Debeir (LISA)
-The goal of this project is to study the applicability of current state-of-the-art text recognition tools in the following practical application. Consider the following two exemplary documents:
+The objective of this master thesis is to build an interpreter/compiler for this declarative CEP language that targets the distributed computing frameworks Apache Spark and/or Apache Storm as backends. Getting aquaintend with these technologies is part of the master thesis objective.
-[[https://dl.dropbox.com/u/5119252/MFE/069-50-3165-1813-00009.jpg]] \\
+**Validation of the approach** Validation of the proposed interpreter/compiler should be done on two levels:
-[[https://dl.dropbox.com/u/5119252/MFE/069-50-3165-1815-00003.jpg]]
+  * a theoretical level; by comparing the generated Spark/Storm processors to a processor based on "Incremental computation" that is being developped at the lab
+  * an experimental level; by proposing a benchmark collection of CEP queries that can be used to test the obtained interpreter/compiler, and report on the experimentally observed performance on this benchmark.
-These two documents are scans of birth certificates (actually both are 2 birth certificates) from the Dutch city Grave. We have a huge collection of such paper documents; about 3 million, of which several tens of thousands have been scanned. Furthermore, we have an index on these documents, created by volunteers. This index contains, for the birth certificate, the name of the child, the name of the father and mother, and the witnesses. As you can see in the documents, however, much more information is available. Your task is to answer the following question: is it realistic, given the current state-of-the-art to do automatic recognition of hand-written texts such as these certificates? Most of the documents are very structured, with limited number of possible values (age of a person, profession), and there is a huge amount of training data; the names of all people have been indexed, usually the handwriting is consistent throughout a whole book with certificates. This graduation project includes a thorough literature study and experimentation with (original combinations of) state-of-the-art image recognition techniques adapted to our specific case. The project will be carried out in collaboration with the research labs WIT and LISA.
+**Deliverables** of the master thesis project
+  * An overview of the processing models of Spark and Storm
+  * A definition of the declarative CEP language under consideration
+  * A description of the interpretation/compilation algorithm
+  * A theoretical comparison of this algorithm wrt an incremental evaluation algorithm.
+  * The interpreter/compiler itself (software artifact)
+  * A benchmark set of CEP queries and associated data sets for the experimental validation
+  * An experimental validation of the compiler, and analysis of the results.
-Interested? Contact [[toon.calders@ulb.ac.be|Toon Calders]]
+**Interested?**
+  * Contact : [[stijn.vansummeren@ulb.ac.be|Stijn Vansummeren]]
-===== Process Mining on Company Data for Detecting Security Breaches =====
+**Status**: available
-Toon Calders (WIT)
-According to a recent report of Price Waterhouse Cooper, the most common source of security incidents are current employees, followed at a distance by former employees and only after that truly external threats such as hactivists. [http://www.pwc.com/gx/en/consulting-services/information-security-survey/giss.jhtml?region=&industry=]  This observation leads to the conclusion that in an intelligent security event management system, should also concentrate on internal threats to security.
-The goal of the thesis is to analyze the possibility of using process mining to help in the detection of silent attacks. We will concentrate on company-specific data. From this data typical behavior will be detected and modeled as a process or workflow. We consider three aspects of a workflow: the actor(s), the resources, and the activities. By modeling the normal behavior in the system we are able to detect deviating cases. Based on historical data, the goal is to build models of typical behavior, including the use of resources such as patient records. Such a system would be able to detect for instance if a certain patient record is consulted much more often than usual, or by more people, or outside of the normal workflow (e.g., only reading information, but not writing). Such a pattern could indicate unjustified access to for instance the patient record of a famous patient.
-For modeling the workflows, we propose the use of process mining (Van der Aalst, 2011). Process mining is a state-of-the-art technology concerned with the automatic extraction of process models from event logs. Consider, e.g., a hospital registering all activities that are carried out for the treatment of patients, ranging from the admission, various measurements being taken from the patient, medicine administered, surgical procedures, to the resignation of the patient. Process mining could be used to extrapolate from these examples, a common model of how the hospital deals with a patient. There are several applications of process mining; first it can be used to improve the processes by standardizing them; many companies and organizations may only have informal procedures. By process mining the process logs are used to extract a general model of the actual business processes. Such a model can guide the automation process.
-In this thesis the goal is to analyze how process mining could be used for anomaly detection; how can the discovered models be used to detect abnormal behavior in a company network? Much like in credit card fraud detection, the approach is to first model normal behavior, in this case using process mining, in order to detect diverging behavior that could indicate security breaches in the network.
-Van der Aalst, W. M. (2011). Process Mining: Discovery, Conformance and Enhancement of Business Processes. Springer.
+===== Graph Indexing for Fast Subgraph Isomorphism Testing =====
+There is an increasing amount of scientific data, mostly from the bio-medical sciences, that can be represented as collections of graphs (chemical molecules, gene interaction networks, ...). A crucial operation when searching in this data is that of subgraph    isomorphism testing: given a pattern P that one is interested in (also a graph) in and a collection D of graphs (e.g., chemical molecules), find all graphs in G that have P as a   subgraph. Unfortunately, the subgraph isomorphism problem is computationally intractable. In ongoing research, to enable tractable processing of this problem, we aim to reduce the number of candidate graphs in D to which a subgraph isomorphism test needs   to be executed. Specifically, we index the graphs in the collection D by means of decomposing them into graphs for which subgraph   isomorphism *is* tractable. An associated algorithm that filters graphs that certainly cannot match P can then formulated based on ideas from information retrieval.
-Interested? Contact [[toon.calders@ulb.ac.be|Toon Calders]]
+In this master thesis project, the student will emperically validate on real-world datasets the extent to which graphs can be decomposed into graphs for which subgraph isomorphism is tractable, and run experiments to validate the effectiveness of the proposed method in terms of filtering power.
-===== Mining patterns for compression =====
+**Interested?** Contact : [[stijn.vansummeren@ulb.ac.be|Stijn Vansummeren]]
-Toon Calders (WIT)
-Data mining is the research discipline that studies the extraction of information from large amounts of data. One of the typical data mining tasks is pattern mining where we try to find regularities that occur frequently in a dataset. The prototypical example is that of a supermarket storing for every customer visiting the supermarket, the transaction; that is, the set of items that were bought by that customer. The frequent itemset mining problem now is to detect which combinations of products were more often sold together than a given threshold. One of the major problems of pattern mining algorithms, however, is the enormous amount of redundant patterns they generate; for instance, very popular items, such as toilet paper, tend to appear in many frequent combinations purely due to chance. In order to deal with this problem, techniques based upon compression and minimum description length were proposed to reduce the number of patterns. The rationale behind the minimal description length principle is that a set of patterns that describes well what is happening in the dataset should allow for a good compression. For a collection of patterns, the quality is measured as the description length of the patterns plus the size of the data compressed with these patterns. For instance, if the pattern {bread, milk, butter} has a high frequency, we could opt to replace every occurrence of this pattern by a special code, effectively reducing the encoding length of the data. Surprisingly, however, the MDL principle was until now only used to rule out redundant patterns, and it has not been researched yet how well the discovered patterns actually do compress the data as compared to compression algorithms such as Lempel–Ziv–Welch.
+**Status**: available
-Hence, in this highly research oriented graduation project, two research questions are central: (1) How good do non-redundant pattern sets based on MDL allow compressing data, and (2) Can we extract useful patterns from existing compression algorithms?
-Interested? Contact [[toon.calders@ulb.ac.be|Toon Calders]]
+===== A Scala-based runtime and compiler for Distributed Datalog =====
-===== Pattern Mining for Object Tracking =====
+Datalog is a fundamental query language in datamanagement based on logic programming. It essentially extends select-from-where SQL queries with recursion. There is a recent trend in data management research to use datalog to specify distributed applications, most notably on the web, as well as do inference on the semantic web. The goal of this thesis is to engineer a basic **distributed datalog system**, i.e., a system that is capable of compiling & running distributed datalog queries. The system should be implemented in the Scala programming language. Learning Scala is part of the master thesis project.
-Toon Calders (WIT)
-Pattern mining techniques are more and more often used in computer vision
+The system should:
-to obtain features that are more discriminative than those extracted
+  * incorporate recently proposed worst-case join algorithms (i.e., the [[http://arxiv.org/abs/1210.0481|leapfrog trie join]])
-using computer vision algorithms. This is true for example in content-based
+  * employ known local datalog optimizations (such as magic sets and QSQ)
-images/videos retrieval, indexing, classiﬁcation, tracking, etc. However, the main
-drawback of using traditional pattern mining techniques is their ineﬃciency when
-dealing with huge set of data (for example provided by Google image or Youtube
-for videos) or when trying to tackle real-time analysis problems. The data mining
-community has been working on the “Big Data” problem for many years coming
-up with promising solutions such as stream mining. The aim of this project
-is to explore the possibility of using pattern mining in data streams for the (real-time) analysis of videos and, in particular, for object tracking.
-For more extensive information regarding the context and problem setting, see the following paper:
+**Validation of the approach** The thesis should propose a benchmark collection of datalog queries and associated data workloads that be used to test the obtained system, and measure key performance characteristics (elasticity of the system; memory frootprint; overall running time, ...)
-Toon Calders, Elisa Fromont, Baptiste Jeudy and Hoang Thanh Lam.
+**Required reading**:
-[[http://labh-curien.univ-st-etienne.fr/~fromont/|Analysis of Videos using Tile Mining.]]\\
+  * Datalog and Recursive Query Processing - Foundations and trends in query processing.
-In: //ECML/PKDD Workshop on Real-World Challenges for Data Stream Mining//, Prague, 2013
+  * LogicBlox, Platform and Language: A Tutorial (Todd J. Green, Molham Aref, and Grigoris Karvounarakis)
+  * Dedalus: Datalog in Time and Space (Peter Alvaro, William R. Marczak, Neil Conway, Joseph M. Hellerstein, David Maier, and Russell Sears)
+  * Declarative Networking (Loo et al). For the distributed evaluation strategy.
+  * Parallel processing of recursive queries in distributed architectures (VLDB 1989)
+  * Evaluating recursive queries in distributed databases (IEEE trans knowledge and data engieneering, 1993)
-Interested? Contact [[toon.calders@ulb.ac.be|Toon Calders]]
+**Deliverables**:
+  * Semantics of datalog; overview of known optimization strategies (document)
+  * Description of the leapfrog trie join (document)
+  * Datalog system (software artifact)
+  * Experimental analysis of developped system on a number of use cases (document)
-===== Master Thesis in Collaboration with Euranova =====
+**Interested?**
+  * Contact : [[stijn.vansummeren@ulb.ac.be|Stijn Vansummeren]]
-Our laboratory performs collaborative research with Euranova R&D (http://euranova.eu/). The list of subjects proposed for this year by Euranova can be found
+**Status**: available
-{{:teaching:mfe:mt2014_euranova.pdf|here}}
-These subject include topics on distributed graph processing, processing big data using Map/Reduce, cloud computing, and social networks.
+===== Développement d’un système de gestion de l’information pour un réseau de dépistage et de suivi des lésions précancéreuses et cancéreuses du col de l’utérus dans la Région de Cochabamba en Bolivie =====
-  * Contact : [[ezimanyi@ulb.ac.be|Esteban Zimanyi]]
+Full description available here:{{:teaching:mfe:mfe_u_bio-mechatronics_codepo_01.docx|}}
-===== Structural compression of relational and semantic web databases =====
-Recent research in database management systems at ULB has shown how to
+**Interested?**
-theoretically construct succinct (compressed) representations for
+  * Contact :   * Contact : [[stijn.vansummeren@ulb.ac.be|Stijn Vansummeren]]
-relational databases and semantic web databases. The advantage of
-these succinct representations is that they allow querying directly
-*on the succinct representation*, without needing to consult the
-underlying database.
-The goal of this thesis is to study scalable algorithms for
+**Status**: available
-constructing the actual succinct representations. Some in-memory
-algorithms are already known, but given the large size of typical
-database, distributed and out-of-memory alternatives need to be found.
-  * Contact : [[stijn.vansummeren@ulb.ac.be|Stijn Vansummeren]]
-===== Aspects of Text Analytics and Information Extraction =====
+=====Publishing and Using Spatio-temporal Data on the Semantic Web=====
-Automatically extracting structured information from text is a task that has been pursued for decades. As a discipline, //Information Extraction// (IE) had its start with the [[http://acl.ldc.upenn.edu/C/C96/C96-1079.pdf|DARPA Message Understanding Conference in 1987]].  While early work in the area focused largely on military applications, recent changes have made information extraction increasingly important to an increasingly broad audience.  Trends such as the rise of social media have produced huge amounts of text data, while analytics platforms like Hadoop have at the same time made the analysis of this data more accessible to a broad range of users.  Since most analytics over text involves information extraction as a first step, IE is a very important part of
-data analysis in the enterprise today.
-Broadly speaking, there are two main schools of thought on the realization of IE: the //statistical// (machine-learning) methodology and the  //rule-based// approach.  The first started with simple models, then progressed to approaches based onprobabilistic graph models. Within the rule-based approach, most of the solutions build upon [[https://www.google.be/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&ved=0CEEQFjAB&url=http%3A%2F%2Fwww.dfki.de%2F~neumann%2Fesslli04%2Freader%2Foverview%2FIJCAI99.pdf&ei=1yZIUdSZPMWHPa2rgagP&usg=AFQjCNFA6QYIt4yNR0oZRL4yjd--kev37A&sig2=nEILF_cNDk4JWiVDS5BXvg&bvm=bv.43828540,d.ZWU|cascaded finite-state  transducers]].  Most systems in both categories were built for academic settings, where most users are highly-trained computational linguists, where workloads cover only a small number of very well-defined tasks and data sets, and where extraction throughput is far less important than the accuracy of results.
+[[http://www.w3c.org/|RDF]] is the [[http://www.w3c.org/|W3C]] proposed framework for representing information
+in the Web. Basically, information in RDF is represented as a set of triples of the form (subject,predicate,object).  RDF syntax is based on directed labeled graphs, where URIs are used as node labels and edge labels. The [[http://linkeddata.org/|Linked Open Data]] (LOD) initiative is aimed at extending the Web  by means of publishing various open datasets as RDF,  setting RDF links between data items from different data sources.  Many companies  and government agencies are moving towards publishing data following the LOD initiative.
+In order to do this, the original data must be transformed into Linked Open Data. Although most of these data are alphanumerical, most of the time they contained  a spatial or spatio-temporal component, that must also be transformed. This can be exploited
+by application providers, that can build attractive and useful applications, in particular, for devices like mobile phones, tablets, etc.
-In practice, these existing tools suffer from a number of practical problems. For example, users need to have an intuitive understanding of machine learning or the ability to build and understand complex and highly interdependent rules. Determining why an extractor produced a given incorrect result
+The goals of this thesis are: (1) study the existing proposals for mapping spatio-temporal data into LOD; (2) apply this mapping to a real-world case study (as was the case for the [[http://www.oscb.be/|Open Semantic Cloud for Brussels]] project; (3) Based on the produced mapping, and using existing applications like the [[http://linkedgeodata.org/|Linked Geo Data project]], build applications that make use of LOD for example, to find out which cultural events are taking place at a given time at a given location.
-is hence often deemed extremely difficult, which makes reuse of extractors across different data sets and applications impractical.  And extremely
-high CPU and memory requirements made extractors cost-prohibitive to deploy over large-scale data sets.
-In 2005, researchers at the IBM Almaden Research Center started work on a new system specifically geared for practical information extraction in the enterprise.  This effort lead to [[https://www.google.be/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&ved=0CEYQFjAB&url=http%3A%2F%2Fciteseerx.ist.psu.edu%2Fviewdoc%2Fdownload%3Fdoi%3D10.1.1.179.356%26rep%3Drep1%26type%3Dpdf&ei=gyhIUe-XPIexPJ-fgLAG&usg=AFQjCNHgkbcREbd6bCA26BVf0FuIZ9n7Sg&sig2=LVQkus_67uSVlwK34BXZ8w&bvm=bv.43828540,d.ZWU|SystemT]] , a rule-based IE system with an SQL-like declarative language named [[http://pic.dhe.ibm.com/infocenter/bigins/v2r0/topic/com.ibm.swg.im.infosphere.biginsights.analyze.doc/doc/aql_overview.html|AQL (Annotation Query Language)]].
+    * Contact: [[ezimanyi@ulb.ac.be|Esteban Zimányi]]
-The declarative nature of AQL enables new kinds of tools for extractor
-development, and a cost-based optimizer for
-performance.
-The goal of this thesis is to study and compare both the
+=====Extending SPARQL for Spatio-temporal Data Support=====
-traditional methods towards information extraction and the new
-AQL-based method proposed by SystemT, based on experimental
-evaluation of information extraction problems on the
-Web. Additional possible topics of study include the (1)
-implementation and optimization aspects of AQL, (2) the extension
-of AQL with probablistic methods, or (3) the inference of AQL
-rules from examples.
+[[http://www.w3.org/TR/rdf-sparql-query/|SPARQL]] is the W3C standard language to query RDF data over the semantic web. Although syntactically similar to SQL,  SPARQL is based on graph matching. In addition, SPARQL is aimed, basically, to query alphanumerical data.
+Therefore, a proposal to extend SPARQL to support spatial data, called  [[http://www.opengeospatial.org/projects/groups/geosparqlswg/|GeoSPARQL]], has been presented to the Open Geospatial Consortium.
+In this thesis we propose to (1) perform an analysis of the current proposal for GeoSPARQL; (2) a study of  current implementations of SPARQL that support spatial data; (3) implement simple extensions for SPARQL to support spatial data, and use these language in real-world use cases.
-Interested? Contact [[stijn.vansummeren@ulb.ac.be|Stijn Vansummeren]]
+   * Contact: [[ezimanyi@ulb.ac.be|Esteban Zimányi]]
-===== Models for programming Data Management in the Cloud =====
+=====Efficient Management of (Sub-)structure  Similarity Search Over Large Graph Databases. =====
-Many say that "The Cloud" is the next computing platform on the
+The problem of (sub-)structure similarity search over graph data has recently drawn significant research interest due to its importance in many application areas such as in Bio-informatics, Chem-informatics, Social Network, Software Engineering, World Wide Web, Pattern Recognition, etc.  Consider, for example, the area of drug design, efficient techniques are required to query and analyze huge data sets of chemical molecules thus shortening the discovery cycle in drug design and other scientific activities.
-Web. Unfortunately, "the cloud" has become a marketing buzzword with
-many different services offered, from the rental of virtual machines,
-to the rental of storage space, to specific compute platforms
-(e.g. MapReduce) that offer transparent parallelization.
-In this thesis, we are interested in the cloud from the point of view
+Graph edit distance is widely accepted as a similarity measure of labeled graphs due to its ability to cope with any kind of graph structures and labeling schemes.  Today, graph edit similarity plays a significant role in managing graph data , and is employed in a variety of analysis tasks such as graph classification and clustering, object recognition in computer vision, etc.
-of data management. There is a recent trend in data management
-research to use logic programming rule-based languages to specify
-distributed applications, most notably on the web, as well as
-inference in the semantic web (see below for a list of
-references). The goal of this thesis is to study, compare, and where
-possible extend the current (logic-programming based) proposals for
-managing data in the cloud.
-  * References:
+In this master thesis project,  due to the hardness of graph edit distance (computing graph edit distance is known to be NP-hard problem), the student  will investigate the current approaches that deals with problem complexity while searching for similar (sub-)structures.  At the end, the student should be able to empirically analyze and contrast some of the interesting approaches.
-       * http://boom.cs.berkeley.edu/
-       * http://p2.cs.berkeley.edu/index.php
-       * http://www.comlab.ox.ac.uk/files/3608/RR-10-21.pdf
-\\
+=====A Generic Similarity Measure For Symbolic Trajectories=====
-  * Contact : [[stijn.vansummeren@ulb.ac.be|Stijn Vansummeren]]
+Moving object databases (MOD) are database systems that can store and manage moving object data. A moving object is a value that changes over time. It can be spatial (e.g., a car driving on the road network), or non-spatial (e.g., the temperature in Brussels). Using a variety of sensors, the changing values of moving objects can be recorded in digital formats. A MOD, then, helps storing and querying such data. There are two types of MOD. The first is the trajectory database, that manages the history of movement. The second type, in contrast, manages the stream of current movement and the prediction of the near future. This thesis belongs to the first type (trajectory databases). The research in this area mainly goes around proposing data persistency models and query operations for trajectory data.
-  * Status: **already taken**
-===== Distributed Structural Indexes for RDF Data =====
+A sub-topic of MOD is the study of semantic trajectories. It is motivated by the fact that the semantic of the movement is lost during the observation process. You GPS logger, for instance, would record a sequence of (lon, lat, time) that describe your trajectory. It won't, however, store the purpose of your trip (work, leisure, …), the transportation mode (car, bus, on foot, …), and other semantics of your trip. Research works have accordingly emerged to extract semantics from the trajectory raw data, and to provide database persistency to semantic trajectories.
-In an effort to enable people to share information in a
+Recently, Ralf Güting et al. published a model called “symbolic trajectories”, which can be viewed as a representation of semantic trajectories:
-structured form on the Web as easily as they can share unstructured
+Ralf Hartmut Güting, Fabio Valdés, and Maria Luisa Damiani. 2015. Symbolic Trajectories. ACM Trans. Spatial Algorithms Syst. 1, 2, Article 7 (July 2015), 51 pages.
-HTML documents today, the World Wide Web Consortium (W3C for short) is
+A symbolic trajectory is a very simple structure composed of a sequence of pairs (time interval, label). So, it is a time dependent label, where every label can tell something about the semantics of the moving object during its associated time interval. We think this model is promising because of its simplicity and genericness.
-calling for the creation of a Web of Linked Data. In the same way as
-one uses HTML and hyperlinks to publish and connect information on the
-Web of Documents, one uses the RDF data model and RDF links to publish
-and connect structured information on the Web of Linked Data. The
-advantage of RDF over HTML lies in its simplicity: all information is
-represented uniformly as triples of the form (subject, predicate,
-object). This allows one to represent both facts about entities (e.g.,
-(Tim Berners-Lee, age, 54)) and links between entities (e.g. (Tim
-Berners-Lee, author of, http://...))  in an easily
-machine-interpretable manner. This is much more difficult with HTML
-where there is little or no constraint on the way information is
-represented.
-Linked Data has the potential to turn the Web into one huge database
+The goal of this thesis is to implement a similarity operator for symbolic trajectories. There are three dimensions of similarity in symbolic trajectories: temporal similarity, value similarity, and semantic similarity. Such an operator should be flexible to express arbitrary combinations of them. It should accept a pair of semantic trajectories and return a numerical value that can be used for clustering or ranking objects based on their similarity. Symbolic trajectories are similar to time series, except that labels are annotated by time intervals, rather than time points. We think that the techniques of time series similarity can be adopted for symbolic trajectories. This thesis should assess that, and implement a similarity measure based on time series similarity. The implementation is required to be done as an extension to PostGIS. We have already implemented some temporal types and operations on top of PostGIS, where you can start from.
-with structured querying capabilities that vastly exceed the limited
-keyword search queries so common on the Web of Documents today.
-As a key component of efficient query answering in Linked Data Management systems, much research is focused on devising high-performance native RDF indexing data structures. One class of such indexes, called structural indexes, seem very promising in this respect. Currently however, structural indexes for RDF are difficult to distribute accross the web. Given the importance of distribution in web-scale data, the goal of this thesis is to investigate how structural RDF indexes can be used in a distributed query answering platform.
+**Deliverables** of the master thesis project
+  * Reporting on the state of art of semantic trajectory similarity measures.
+  * Reporting on the state of art in time series similarity measures.
+  * Assessing the application of time series similarity to symbolic trajectories.
+  * Implementing symbolic trajectories on top of PostGIS.
+  * Implementation and evaluating the proposed symbolic trajectory similarity operator.
-  * Contact : [[stijn.vansummeren@ulb.ac.be|Stijn Vansummeren]]
+**Interested?**
+  * Contact : [[ezimanyi@ulb.ac.be|Esteban Zimanyi]]
+**Status**: available
+=====Assessing Existing Communication Protocols In The Context Of DaaS =====
+Data-as-a-Service (DaaS) is an emerging cloud model. The main offering of DaaS is to allow data producers/owners to publish data services on the cloud. The idea of publishing data via a service interface is not new. SOA protocols have enabled this long ago. Yet, these protocols were not developed with the cloud and the big data in mind. This is probably why the term DaaS has emerged. It marks the need for protocols and tools that enable big data exchange.
-=====Publishing and Using Spatio-temporal Data on the Semantic Web=====
+DaaS services need to exchange large amounts of data. Large here refers to large message size, large message count, or a combination of both. RESTful services, for instance, communicate over HTTP, which is not a good choice for communicating large messages/files. SOAP services are not bound to HTTP, but they introduce another overhead of requiring messages to be strictly formatted in XML. This is why researchers started to reconsider older protocols like the BitTorrent, and suggesting extension to existing protocols like the SOAP with Attachments.
+The topic of this thesis is to perform a comprehensive survey on the protocols data exchange, and assess their suitability for DaaS. A quantitative comparison of protocols need to be done, considering at least these two dimensions: (1) the protocol: SOAP, REST, BitTorrent, etc, and (2) the message: short inline, long inline, file. The assessment should be in terms of reliability, performance, and security.
-[[http://www.w3c.org/|RDF]] is the [[http://www.w3c.org/|W3C]] proposed framework for representing information
+**Deliverables** of the master thesis project
-in the Web. Basically, information in RDF is represented as a set of triples of the form (subject,predicate,object).  RDF syntax is based on directed labeled graphs, where URIs are used as node labels and edge labels. The [[http://linkeddata.org/|Linked Open Data]] (LOD) initiative is aimed at extending the Web  by means of publishing various open datasets as RDF,  setting RDF links between data items from different data sources.  Many companies  and government agencies are moving towards publishing data following the LOD initiative.
+  * A report that reviews the state of art communication protocols.
-In order to do this, the original data must be transformed into Linked Open Data. Although most of these data are alphanumerical, most of the time they contained  a spatial or spatio-temporal component, that must also be transformed. This can be exploited
+  * Propose a tool for DaaS developers to choose the best protocol/s based on their application needs. Such a tool might also provide means of automatically switching between protocols on certain thresholds.
-by application providers, that can build attractive and useful applications, in particular, for devices like mobile phones, tablets, etc.
+  * Experiments to assess the suitability of protocols for DaaS, and to compare between them. These experiments need to be repeatable, so that others can use them on their own datasets and configurations.
-The goals of this thesis are: (1) study the existing proposals for mapping spatio-temporal data into LOD; (2) apply this mapping to a real-world case study (as was the case for the [[http://www.oscb.be/|Open Semantic Cloud for Brussels]] project; (3) Based on the produced mapping, and using existing applications like the [[http://linkedgeodata.org/|Linked Geo Data project]], build applications that make use of LOD for example, to find out which cultural events are taking place at a given time at a given location.
+**Interested?**
+  * Contact : [[ezimanyi@ulb.ac.be|Esteban Zimanyi]]
-    * Contact: [[ezimanyi@ulb.ac.be|Esteban Zimányi]]
+**Status**: available
-=====Extending SPARQL for Spatio-temporal Data Support=====
-[[http://www.w3.org/TR/rdf-sparql-query/|SPARQL]] is the W3C standard language to query RDF data over the semantic web. Although syntactically similar to SQL,  SPARQL is based on graph matching. In addition, SPARQL is aimed, basically, to query alphanumerical data.
-Therefore, a proposal to extend SPARQL to support spatial data, called  [[http://www.opengeospatial.org/projects/groups/geosparqlswg/|GeoSPARQL]], has been presented to the Open Geospatial Consortium.
-In this thesis we propose to (1) perform an analysis of the current proposal for GeoSPARQL; (2) a study of  current implementations of SPARQL that support spatial data; (3) implement simple extensions for SPARQL to support spatial data, and use these language in real-world use cases.
-   * Contact: [[ezimanyi@ulb.ac.be|Esteban Zimányi]]