34 research outputs found
Searching Multi-Hierarchical XML Documents: the Case of Fragmentation
To properly encode properties of textual documents using XML, multiple markup hierarchies must be used, often leading to conflicting markup in encodings. Text Encoding Initiative (TEI) Guidelines [1] recognize this problem and suggest a number of ways to incorporate multiple hierarchies in a single well-formed XML document. In this paper, we present a framework for processing XPath queries over multi-hierarchical XML documents represented using fragmentation, one of the TEI-suggested techniques. We define the semantics of XPath over DOM trees of fragmented XML, extend the path expression language to cover overlap in markup, and describe FragXPath, our implementation of the proposed XPath semantics over fragmented markup
A Hierarchical Extension of the D ∗ Algorithm
In this paper a contribution to the practice of path planning using a new hierarchical
extension of the D
∗ algorithm is introduced. A hierarchical graph is stratified into several abstraction
levels and used to model environments for path planning. The hierarchical D∗ algorithm uses a downtop
strategy and a set of pre-calculated trajectories in order to improve performance. This allows
optimality and specially lower computational time. It is experimentally proved how hierarchical
search algorithms and on-line path planning algorithms based on topological abstractions can be
combined successfully
Hierarchical D ∗ algorithm with materialization of costs for robot path planning
In this paper a new hierarchical extension of the D
∗ algorithm for robot path planning is introduced. The hierarchical D
∗
algorithm uses a down-top strategy and a set of precalculated paths (materialization of path costs) in order to improve performance.
This on-line path planning algorithm allows optimality and specially lower computational time. H-Graphs (hierarchical graphs)
are modified and adapted to support on-line path planning with materialization of costs and multiple hierarchical levels. Traditional
on-line robot path planning focused in horizontal spaces is also extended to vertical and interbuilding spaces. Some experimental
results are showed and compared to other path planning algorithms
Tagging, Folksonomy & Co - Renaissance of Manual Indexing?
This paper gives an overview of current trends in manual indexing on the Web.
Along with a general rise of user generated content there are more and more
tagging systems that allow users to annotate digital resources with tags
(keywords) and share their annotations with other users. Tagging is frequently
seen in contrast to traditional knowledge organization systems or as something
completely new. This paper shows that tagging should better be seen as a
popular form of manual indexing on the Web. Difference between controlled and
free indexing blurs with sufficient feedback mechanisms. A revised typology of
tagging systems is presented that includes different user roles and knowledge
organization systems with hierarchical relationships and vocabulary control. A
detailed bibliography of current research in collaborative tagging is included.Comment: Preprint. 12 pages, 1 figure, 54 reference
Multi-level chirality in liquid crystals formed by achiral molecules
M.S., D.P., and N.V. acknowledge the support of the National Science Centre (Poland) under the grant no. 2016/22/A/ST5/00319. E.G. acknowledges the funding from the Foundation for Polish Science through the Sabbatical Fellowships Program. N.V. acknowledges the support of the Slovenian Research Agency (ARRS), through the research core funding no. P1-0055. R.W. gratefully acknowledges the Carnegie Trust for the Universities of Scotland for funding the award of a PhD scholarship. The beamline 11.0.1.2 at the Advanced Light Source at the Lawrence Berkeley National Laboratory is supported by the director of the Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.Peer reviewedPublisher PD
A multiple layer model to compare RNA secondary structures
International audienceWe formally introduce a new data structure, called MiGaL for ``Multiple Graph Layers'', that is composed of various graphs linked together by relations of abstraction/refinement. The new structure is useful for representing information that can be described at different levels of abstraction, each level corresponding to a graph. We then propose an algorithm for comparing two MiGaLs. The algorithm performs a step-by-step comparison starting with the most ``abstract'' level. The result of the comparison at a given step is communicated to the next step using a special colouring scheme. MiGaLs represent a very natural model for comparing RNA secondary structures that may be seen at different levels of detail, going from the sequence of nucleotides, single or paired with another to participate in a helix, to the network of multiple loops that is believed to represent the most conserved part of RNAs having similar function. We therefore show how to use MiGaLs to very efficiently compare two RNAs of any size at different levels of detail
Pattern-based design applied to cultural heritage knowledge graphs
Ontology Design Patterns (ODPs) have become an established and recognised
practice for guaranteeing good quality ontology engineering. There are several
ODP repositories where ODPs are shared as well as ontology design methodologies
recommending their reuse. Performing rigorous testing is recommended as well
for supporting ontology maintenance and validating the resulting resource
against its motivating requirements. Nevertheless, it is less than
straightforward to find guidelines on how to apply such methodologies for
developing domain-specific knowledge graphs. ArCo is the knowledge graph of
Italian Cultural Heritage and has been developed by using eXtreme Design (XD),
an ODP- and test-driven methodology. During its development, XD has been
adapted to the need of the CH domain e.g. gathering requirements from an open,
diverse community of consumers, a new ODP has been defined and many have been
specialised to address specific CH requirements. This paper presents ArCo and
describes how to apply XD to the development and validation of a CH knowledge
graph, also detailing the (intellectual) process implemented for matching the
encountered modelling problems to ODPs. Relevant contributions also include a
novel web tool for supporting unit-testing of knowledge graphs, a rigorous
evaluation of ArCo, and a discussion of methodological lessons learned during
ArCo development
NAPG: Non-Autoregressive Program Generation for Hybrid Tabular-Textual Question Answering
Hybrid tabular-textual question answering (QA) requires reasoning from
heterogeneous information, and the types of reasoning are mainly divided into
numerical reasoning and span extraction. Despite being the main challenge of
the task compared to extractive QA, current numerical reasoning method simply
uses LSTM to autoregressively decode program sequences, and each decoding step
produces either an operator or an operand. However, the step-by-step decoding
suffers from exposure bias, and the accuracy of program generation drops
sharply with progressive decoding. In this paper, we propose a
non-autoregressive program generation framework, which facilitates program
generation in parallel. Our framework, which independently generates complete
program tuples containing both operators and operands, can significantly boost
the speed of program generation while addressing the error accumulation issue.
Our experiments on the MultiHiertt dataset shows that our model can bring about
large improvements (+7.97 EM and +6.38 F1 points) over the strong baseline,
establishing the new state-of-the-art performance, while being much faster
(21x) in program generation. The performance drop of our method is also
significantly smaller than the baseline with increasing numbers of numerical
reasoning steps
Mobile Robot Navigation in Indoor Environments: Geometric, Topological, and Semantic Navigation
The objective of the chapter is to show current trends in robot navigation systems related to indoor environments. Navigation systems depend on the level of abstraction of the environment representation. The three main techniques for representing the environment will be described: geometric, topological, and semantic. The geometric representation of the environment is closer to the sensor and actuator world and it is the best one to perform local navigation. Topological representation of the environment uses graphs to model the environment and it is used in large navigation tasks. The semantic representation is the most abstract representation model and adds concepts such as utilities or meanings of the environment elements in the map representation. In addition, regardless of the representation used for navigation, perception plays a significant role in terms of understanding and moving through the environment