Sergio A. Alvarez
Ph.D., University of Maryland at College Park
Research
Combination functions for integration of information sources
I have developed a methodology for the systematic generation of
"combination functions" that allow the integration of two or more
numerical measures (representing disparate information sources) into
a single combined measure. There is a need for such combination
functions in database integration, in management of uncertainty in
knowledge-based systems, and in various experimental studies in
biology and psychology.
My approach uses a single canonical combination function to
generate a multitude of combination functions by choosing
appropriate "reference frames" in the space in which the
measures take their values.
Most recently, my work
in this area has been presented at the 6th International
Symposium on Artificial Intelligence and Mathematics,
Ft. Lauderdale, FL, Jan. 2000, and at the Workshop on Soft
Computing, Marianska u Jachymova, Czech Republic, Nov. 1999.
Performance trade-off in information retrieval and filtering
A trade-off between the measures known as recall and precision
has been widely observed by researchers in information retrieval.
The mechanisms underlying such a trade-off are less well understood.
Recent work involving the application of machine learning techniques
to information retrieval problems require the use of slightly
different measures of performance, including the classification
accuracy. I have obtained results that rigorously establish a
trade-off between recall and precision in this context.
Computational modeling and analysis
I am interested in combining analytical and computational techniques
to understand natural and engineering systems. My work in this
direction includes optimization applied to orbital dynamics,
computational metrics for neurobiological data,
and analysis of mathematical models of phase transitions.
My papers in this area have been accepted for publication
in the following refereed journals: Journal of Guidance,
Control, and Dynamics, Bulletin of Mathematical Biology,
and Differential and Integral Equations.
Publications
Lin, W.-Y., Alvarez, S.A., Ruiz, C.,
"Collaborative Recommendation via Adaptive Asociation Rule Mining",
KDD-2000 Workshop on Web Mining for E-Commerce,
Boston, MA, Aug. 2000
Alvarez, S.A.,
"Web Metasearch as Belief Aggregation",
AAAI-2000 Workshop on AI for Web Search,
Austin, TX, July 2000
Alvarez, S. A.,
"Belief Combination by means of Frame Transformations",
6th International Symposium on Artificial Intelligence and Mathematics,
Ft. Lauderdale, FL, Jan. 2000
Lin, W.-Y., Ruiz, C., Alvarez, S.A.,
"A New Adaptive-Support Algorithm for Asociation Rule Mining",
Technical Report WPI-CS-TR-00-13, Department of Computer Science,
Worcester Polytechnic Institute, May 2000
Streeter, M.J., Ward, M.O., Alvarez, S.A.,
"N2VIS: An Interactive Visualization Tool for Neural Networks",
Technical Report WPI-CS-TR-00-11, Department of Computer Science,
Worcester Polytechnic Institute, March 2000
Carter, T., Alvarez, S. A.,
"Quadratic-based Computation of Optimal Four-Impulse Rendezvous
Near a Circular Orbit",
Journal of Guidance, Control, and Dynamics, vol. 23, no. 1,
Jan.-Feb. 2000, 109-117 abstract (HTML)
Alvarez, S. A.,
"A Geometric Theory of Knowledge Aggregation",
Workshop on Soft Computing, Marianska u Jachymova,
Czech Republic, Nov. 1999
Alvarez, S. A., Levitan, S.L., Reggia, J.A.,
"Metrics for Cortical Map Organization and Asymmetry",
Bulletin of Mathematical Biology, vol. 60 (1998), 27-47;
Carter, T., Alvarez, S. A.,
"Four-Impulse Rendezvous near Circular Orbit",
AIAA/AAS Astrodynamics Specialist Conference,
Session 84-ASD-10, Rendezvous and Orbit Transfer,
Boston, MA, Aug. 1998
Alvarez, S.A.
"Rational comparison of probabilities via a blow-up conjugacy",
Research Report No. 97-NA-010, Center for Nonlinear Analysis,
Carnegie Mellon U., Aug. 1997 abstract (HTML)
Alvarez, S.A., Liu, C.
"Initial Data Dependence for Motion by Minus the Surface
Laplacian of Curvature", Differential and Integral Equations,
accepted; also see
Research Report No. 97-NA-009, Center for Nonlinear Analysis,
Carnegie Mellon U., Aug. 1997
abstract (HTML)
Alvarez, S.A.
Interface Motion Driven by Curvature and
Diffusion: Analytic Dependence on the Initial Data
for the Mullins-Sekerka Equation",
Ph.D. Thesis, University of Maryland at College Park, 1996 abstract (HTML)
Alvarez, S. A.,
"Homothetic Invariance of the Space L0(\mu)",
J. of Math. Analysis and Appl.,
vol. 179, no. 1, 260-274, Oct. 1993
abstract (DVI)
Alvarez, S. A.,
"Lp Arithmetic",
Am. Math. Monthly,
vol. 99, no. 7, 656-662, Aug.-Sept. 1992
abstract (DVI)
Alvarez, S. A.,
"Lattices Generated by Collections of Lp Spaces" Rev. Col. Mat., vol. XXII, 1988
Alvarez, S. A., Noreña, D., Ramos, E.,
``Automated Recognition of Handprinted Alphanumeric Characters'',
Sistemas, No. 23, Apr.-Jun. 1985
abstract (DVI)
Research according to Hollywood
"Do you have any idea how easy this stuff is for me ?!?"
Exasperated 20 year old janitor/genius Will Hunting
trying to explain a mathematical proof to a struggling
Fields Medalist in Good Will Hunting, Miramax Films, 1997