David L.
Waltz, a computer scientist whose early research in information retrieval
provided the foundation for today’s Internet search engines, died on Thursday
in
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Eileen Barroso for
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The cause was brain cancer, his
wife, Bonnie Waltz, said. He died at the
During his career as a teacher and a
technologist at start-up companies as well as large corporate laboratories, Dr.
Waltz made fundamental contributions to computer science in areas ranging from
computer vision to machine learning.
One signal achievement was the
development of a basic technique that makes it possible for computers to render
three-dimensional scenes accurately. As part of his Ph.D. dissertation at the
Massachusetts Institute of Technology, he developed an algorithm that could
extract a rich three-dimensional understanding of a scene from two-dimensional
line drawings with shadows.
The 3-D research was seminal in the
fields of computer vision and artificial intelligence. Known as “constraint
propagation,” the technique is now used in industry for solving problems like
route scheduling, package routing and construction scheduling.
At M.I.T., Dr. Waltz was taught by
Marvin Minsky, a pioneer in artificial intelligence. Dr. Waltz graduated in
1972, then taught computer science at the
But it was as a member of a group of
researchers at the Thinking Machines Corporation, in
“For the first time it was possible
to use simple algorithms with lots and lots of data,” said Brewster Kahle, a
computer scientist who directs the Internet Archives and was one of the
Thinking Machines researchers.
Access to that database was crucial
to Dr. Waltz’s development of a technique known as memory, or “case based,”
reasoning. It revolutionized the way computers recognized characters, words,
images and later, even voices. Before, a computer had to follow a set of
programmed rules to arrive at recognition (it’s an “i” if there’s a dot, for
example). Now it could comb through its vast memory and deduce what the image
was by comparing it to what had been stored there.
The technique transformed the field
of artificial intelligence and also greatly advanced voice recognition and
machine vision technology. And it led directly to the “big data” and
data-science approaches that are essential tools for search engines, allowing
them to sift through large collections of information to improve accuracy and
relevance.
“He was a real pioneer,” said Peter
Norvig, Google’s director of research. “The two main changes that got us modern
A.I. were probabilistic reasoning and using memory rather than rules.”
“I don’t know if Larry and Sergey
read his papers directly,” he added, referring to Google’s founders, Larry Page
and Sergey Brin, “but the idea, filtered through however many people, was
certainly a key.”
While at the
In another early project, a Thinking
Machines group led by Dr. Waltz designed an information retrieval system that
made it possible for a remote user to gain access to a supercomputer and then
be able to search through large volumes of documents.
The system, known as Wide Area
Information Server, or WAIS, and designed in cooperation with the Dow Jones
Corporation, Apple Computer and KPMG Peat Marwick, was not the first
information retrieval system. But it was innovative in enabling the user to
uncover connections between seemingly disparate documents. For example, the
WAIS system was able to give an early warning of the
WAIS also introduced techniques to
narrow a document search. It was followed by other search systems, like
Veronica, Gopher and Archie, which predated the search engines offered today by
Google, Microsoft, Yahoo and other companies.
After leaving Thinking Machines in
1993, Dr. Waltz joined the NEC Research Institute in
The center has worked with Con
Edison of New York in developing systems that can predict power failures and
thus enhance maintenance of the electric power grid. Researchers there are also
working on creating a computer-based system to give people with epilepsy early
warnings of seizures. The technique involves mining data generated by
electrodes implanted in patients.
Dr. Waltz earlier was instrumental
in establishing interdisciplinary research centers: the Beckman Institute at
the
David Leigh Waltz was born in
Besides his wife, he is survived by
a brother, Peter; a son, Jeremy; a daughter, Vanessa Waltz, and a
granddaughter.