Traducción del inglés al castellano (sin diccionario), correspondiente al examen para la
V convocatoria de la Oposición al Cuerpo Superior de Sistemas y Tecnologías de la
Información. Tiempo asignado : Una hora exacta
The Galaxy’s guide to the hitch-hiker
IN FILMS about the future, computers generally feature either as electronic
personifications of evil, or as your plastic pal who’s fun to be with. But whichever
guise they appear in, they differ from the cussed, keyboard-driven creatures
familiar to contemporary man in two important ways. They can listen. And they can
Talking is not too difficult , speech-synthesis programs have around for a while,
though computers are hardly great conversationalists. Listening and, more
importantly, understanding, though, is still mostly science fiction. But the desire to
design a listening machine is strong in software engineers. So strong that they have
been at it for several decades, with what might generously be described as limited
The problems are legion. The computer must first recognize each word in a
sentence, even when spoken in a sloppy, everyday cadence. It must parse the
sentence into its grammatical elements. It must then try to understand the meaning
of what it has parsed, and finally it must act on it.
This is a formidable task, particularly for the limited brains of the personal
computers (PCs) on which a useful system would have to run. But on top of all
this, there is the problem of context. Critics of a philosophical bent argue that
language is a social activity requiring shared background assumptions. Since those
assumptions can never be completely listed, they cannot be programmed into a
The Spoken Language Systems Group at the Massachusetts Institute of Technology
Laboratory for Computer Science, which is led by Victor Zue, thinks, however, that
it has gone some way to dealing with these difficulties. It has done so by removing
most of the processing problem from the PCs to powerful central machines that can
do some serious word-crunching, and by dodging the issue of context.
Dr. Zue’s systems restrict context by operating in limited “knowledge domains”.
Two prototypes that have running for the past few years are extremely limited.
Voyager is a user’s guide to Cambridge, helping people to find their way to
Chinese restaurants and other tourists necessities. And Pegasus is connected to the
American Airlines Eaasy reservation system. But a third system, Galaxy, which Dr.
Zue is in the process of developing, manages to have it both ways. By operating in a bigger virtual world —the World Wide Web of the Internet —it can link disparate knowledge domains together in a way that is invisible to the user.
Galaxy’s goal is to do for the Internet what graphical icons did for personal
computers —give it an intuitive feel that anyone can grasp. A person asking Galaxy
for help does not need to know who created the information sought, which
computer it sits on, its address on the network, or even its “transmission protocol”
(i.e., which acronym or jokey mnemonic —such as ftp, gopher or http —is needed
to fetch it). He merely asks, “What will the weather be like tomorrow in
Manhattan?” and, with luck, the answer will come back in a few seconds (though
not necessarily any more accurately than if he had got it from a human weather
forecaster). And if Galaxy does not understand the first time, it can ask
supplementary questions, like an interviewer trying to pin down the ambiguities of
Galaxy’s manifestation in a user’s PC is a small program known as a client. This
serves merely as a courier, shuttling the user’s questions to a piece of heavyweight
silicon known as a language server, and then taking the server’s reply and
delivering it back to the PC’s user. The language servers do the computationally
intensive work of speech recognition and language processing. Each also knows
how to interrogate the relevant “knowledge server” for the question at hand. These
machines find the data a language server needs to compose answers for the original
PC’s client program to turn into synthesized speech (or a typed text for those
unfortunates still chained to a screen). Making all this possible requires an
enormous amount of programming.
The basic research that Dr. Zue’s team has had to carry out in order to write
Galaxy’s programs includes modelling how people hear, what linguistic regularities
pop up in their spontaneous speech (which may, in this context, be English,
Spanish, Chinese or Japanese), and how to deal with such problems as foreign
accents. For only having understood the question (Galaxy knows more than 4.000
english words, and dealing with unknown ones was yet another wrinkle that Dr.
Zue’s team had to iron out), can the server then seek an answer from the
appropriate knowledge domain.
Ultimately, Dr. Zue hopes to eliminate the PC altogether, and have a system that
answers questions down a telephone. Whether other people will create enough
knowledge-domain servers out there to provide the answers, and whether they will
be fun to be with, remains to be seen.