19,731 research outputs found
There is no tame triangulation of the infinite real Grassmannian
We show that there is no triangulation of the infinite real Grassmannian of
k-planes in R^\infty which is nicely situated with respect to the coordinate
axes. In terms of matroid theory, this says there is no triangulation of the
Grassmannian subdividing the matroid stratification. This is proved by an
argument in projective geometry, considering a specific sequence of
configurations of points in the plane.Comment: 11 page
The Phone Walkers: A study of human dependence on inactive mobile devices
The development of mobile phones has largely increased human interactions.
Whilst the use of these devices for communication has received significant
attention, there has been little analysis of more passive interactions. Through
census data on casual social groups, this work suggests a clear pattern of
mobile phones being carried in people's hands, without the person using it
(that is, not looking at it). Moreover, this study suggests that when
individuals join members of the opposite sex there is a clear tendency to stop
holding mobile phones whilst walking. Although it is not clear why people hold
their phones whilst walking in such large proportions (38% of solitary women,
and 31% of solitary men), we highlight several possible explanation for holding
the device, including the need to advertise status and affluence, to maintain
immediate connection with friends and family, and to mitigate feelings related
to anxiety and security.Comment: To appear in "Behaviour". 21 pages; 7 figures; Appendix in journal
version onl
Sparsity and `Something Else': An Approach to Encrypted Image Folding
A property of sparse representations in relation to their capacity for
information storage is discussed. It is shown that this feature can be used for
an application that we term Encrypted Image Folding. The proposed procedure is
realizable through any suitable transformation. In particular, in this paper we
illustrate the approach by recourse to the Discrete Cosine Transform and a
combination of redundant Cosine and Dirac dictionaries. The main advantage of
the proposed technique is that both storage and encryption can be achieved
simultaneously using simple processing steps.Comment: Revised manuscript- Software for implementing the Encrypted Image
Folding proposed in this paper is available on
http://www.nonlinear-approx.info
Entity Query Feature Expansion Using Knowledge Base Links
Recent advances in automatic entity linking and knowledge base
construction have resulted in entity annotations for document and
query collections. For example, annotations of entities from large
general purpose knowledge bases, such as Freebase and the Google
Knowledge Graph. Understanding how to leverage these entity
annotations of text to improve ad hoc document retrieval is an open
research area. Query expansion is a commonly used technique to
improve retrieval effectiveness. Most previous query expansion
approaches focus on text, mainly using unigram concepts. In this
paper, we propose a new technique, called entity query feature
expansion (EQFE) which enriches the query with features from
entities and their links to knowledge bases, including structured
attributes and text. We experiment using both explicit query entity
annotations and latent entities. We evaluate our technique on TREC
text collections automatically annotated with knowledge base entity
links, including the Google Freebase Annotations (FACC1) data.
We find that entity-based feature expansion results in significant
improvements in retrieval effectiveness over state-of-the-art text
expansion approaches
- …