660 research outputs found
Automatic Classification of Text Databases through Query Probing
Many text databases on the web are "hidden" behind search interfaces, and
their documents are only accessible through querying. Search engines typically
ignore the contents of such search-only databases. Recently, Yahoo-like
directories have started to manually organize these databases into categories
that users can browse to find these valuable resources. We propose a novel
strategy to automate the classification of search-only text databases. Our
technique starts by training a rule-based document classifier, and then uses
the classifier's rules to generate probing queries. The queries are sent to the
text databases, which are then classified based on the number of matches that
they produce for each query. We report some initial exploratory experiments
that show that our approach is promising to automatically characterize the
contents of text databases accessible on the web.Comment: 7 pages, 1 figur
Structure of Higher Spin Gauge Interactions
In a previous paper, higher spin gauge field theory was formulated in an
abstract way, essentially only keeping enough machinery to discuss "gauge
invariance" of an "action". The approach could be thought of as providing an
interface (or syntax) towards an implementation (or semantics) yet to be
constructed. The structure then revealed turns out to be that of a strongly
homotopy Lie algebra.
In the present paper, the framework will be connected to more conventional
field theoretic concepts. The Fock complex vertex operator implementation of
the interactions in the BRST-BV formulation of the theory will be elaborated.
The relation between the vertex order expansion and homological perturbation
theory will be clarified. A formal non-obstruction argument is reviewed. The
syntactically derived sh-Lie algebra structure is semantically mapped to the
Fock complex implementation and it is shown that the recursive equations
governing the higher order vertices are reproduced.
Global symmetries and subsidiary conditions are discussed and as a result the
tracelessness constraints are discarded. Thus all equations needed to compute
the vertices to any order are collected. The framework is general enough to
encompass all possible interaction terms.
Finally, the abstract framework itself will be strengthened by showing that
it can be naturally phrased in terms of the theory of categories.Comment: A few changes and additions made in the Introduction. Three
references added. Typos corrected. Text agrees with published version in J.
Math. Phys. except for minor journal specific proof-reading changes. 61 page
Microscale distribution patterns of terrestrial bryophytes in a subalpine forest: the use of logistic regression as an interpretive tool
This study investigated microhabitat relationships of terrestrial bryophytes in a subalpine forest of coastal British Columbia. Substratum affinities were characterized for dominant bryophytes. Logistic regression analysis was used to gain insight into the ecological determinants of fine scale (0.1 m2) bryophyte distribution by examining the predictive relationship between bryophyte species occurrence and localized environmental conditions, as well as the coverage of other bryophytes. The predictive relationships were compared to evaluate the relative importance of environmental factors versus interspecific interactions in structuring bryophyte communities. The results indicate that bryophytes show unique responses in their relationships to environmental conditions and other bryophytes. Positive feedback appears to be an important process among terrestrial bryophytes in subalpine forests
- …