122 research outputs found
Contract bridge as a micro-world for reasoning about communication agents
We argue that bidding in the game of Contract Bridge can profitably be
regarded as a micro-world suitable for experimenting with pragmatics. We sketch an
analysis in which a "bidding system" is treated as the semantics of an artificial
language, and show how this "language", despite its apparent simplicity, is capable of
supporting a wide variety of common speech acts parallel to those in natural languages;
we also argue that the reason for the relatively unsuccessful nature of previous
attempts to write strong Bridge playing programs has been their failure to address the
need to reason explicitly about knowledge, pragmatics, probabilities and plans. We give
an overview of Pragma, a system currently under development at SICS, which embodies
these ideas in concrete form, using a combination of rule-based inference, stochastic
simulation, and "neural-net" learning. Examples are given illustrating the functionality
of the system in its current form
The Speech-Language Interface in the Spoken Language Translator
The Spoken Language Translator is a prototype for practically useful systems
capable of translating continuous spoken language within restricted domains.
The prototype system translates air travel (ATIS) queries from spoken English
to spoken Swedish and to French. It is constructed, with as few modifications
as possible, from existing pieces of speech and language processing software.
The speech recognizer and language understander are connected by a fairly
conventional pipelined N-best interface. This paper focuses on the ways in
which the language processor makes intelligent use of the sentence hypotheses
delivered by the recognizer. These ways include (1) producing modified
hypotheses to reflect the possible presence of repairs in the uttered word
sequence; (2) fast parsing with a version of the grammar automatically
specialized to the more frequent constructions in the training corpus; and (3)
allowing syntactic and semantic factors to interact with acoustic ones in the
choice of a meaning structure for translation, so that the acoustically
preferred hypothesis is not always selected even if it is within linguistic
coverage.Comment: 9 pages, LaTeX. Published: Proceedings of TWLT-8, December 199
Hybrid language processing in the Spoken Language Translator
The paper presents an overview of the Spoken Language Translator (SLT)
system's hybrid language-processing architecture, focussing on the way in which
rule-based and statistical methods are combined to achieve robust and efficient
performance within a linguistically motivated framework. In general, we argue
that rules are desirable in order to encode domain-independent linguistic
constraints and achieve high-quality grammatical output, while corpus-derived
statistics are needed if systems are to be efficient and robust; further, that
hybrid architectures are superior from the point of view of portability to
architectures which only make use of one type of information. We address the
topics of ``multi-engine'' strategies for robust translation; robust bottom-up
parsing using pruning and grammar specialization; rational development of
linguistic rule-sets using balanced domain corpora; and efficient supervised
training by interactive disambiguation. All work described is fully implemented
in the current version of the SLT-2 system.Comment: 4 pages, uses icassp97.sty; to appear in ICASSP-97; see
http://www.cam.sri.com for related materia
Abductive Equivalential Translation and its application to Natural Language Database Interfacing
The thesis describes a logical formalization of natural-language database
interfacing. We assume the existence of a ``natural language engine'' capable
of mediating between surface linguistic string and their representations as
``literal'' logical forms: the focus of interest will be the question of
relating ``literal'' logical forms to representations in terms of primitives
meaningful to the underlying database engine. We begin by describing the nature
of the problem, and show how a variety of interface functionalities can be
considered as instances of a type of formal inference task which we call
``Abductive Equivalential Translation'' (AET); functionalities which can be
reduced to this form include answering questions, responding to commands,
reasoning about the completeness of answers, answering meta-questions of type
``Do you know...'', and generating assertions and questions. In each case, a
``linguistic domain theory'' (LDT) and an input formula are given,
and the goal is to construct a formula with certain properties which is
equivalent to , given and a set of permitted assumptions. If the
LDT is of a certain specified type, whose formulas are either conditional
equivalences or Horn-clauses, we show that the AET problem can be reduced to a
goal-directed inference method. We present an abstract description of this
method, and sketch its realization in Prolog. The relationship between AET and
several problems previously discussed in the literature is discussed. In
particular, we show how AET can provide a simple and elegant solution to the
so-called ``Doctor on Board'' problem, and in effect allows a
``relativization'' of the Closed World Assumption. The ideas in the thesis have
all been implemented concretely within the SRI CLARE project, using a real
projects and payments database. The LDT for the example database is described
in detail, and examples of the types of functionality that can be achieved
within the example domain are presented.Comment: 162 pages, Latex source, PhD thesis (U Stockholm, 1993). Uses
style-file ustockholm_thesis.st
Adapting the Core Language Engine to French and Spanish
We describe how substantial domain-independent language-processing systems
for French and Spanish were quickly developed by manually adapting an existing
English-language system, the SRI Core Language Engine. We explain the
adaptation process in detail, and argue that it provides a fairly general
recipe for converting a grammar-based system for English into a corresponding
one for a Romance language.Comment: 9 pages, aclap.sty; to appear in NLP+IA 96; see also
http://www.cam.sri.com
Finding out = Achieving Decidability
We present a framework for reasoning about the concepts of "knowing
what" and "finding out", in which the key concept is to identify "finding out
the answer to question Q" with "achieving a situation in which Q is decidable"
. We give examples of how the framework can be used to formulate non-trivial
problems involving the construction of plans to acquire and use information,
and go on to demonstrate that these problems can often be solved by systematic
application of a small set of goal-directed backward-chaining rules. In
conclusion, it is suggested that systems of this kind are potentially
implementable in l-Prolog, a logic programming language based on higher-order
logic
Estimating Performance of Pipelined Spoken Language Translation Systems
Most spoken language translation systems developed to date rely on a
pipelined architecture, in which the main stages are speech recognition,
linguistic analysis, transfer, generation and speech synthesis. When making
projections of error rates for systems of this kind, it is natural to assume
that the error rates for the individual components are independent, making the
system accuracy the product of the component accuracies.
The paper reports experiments carried out using the SRI-SICS-Telia Research
Spoken Language Translator and a 1000-utterance sample of unseen data. The
results suggest that the naive performance model leads to serious overestimates
of system error rates, since there are in fact strong dependencies between the
components. Predicting the system error rate on the independence assumption by
simple multiplication resulted in a 16\% proportional overestimate for all
utterances, and a 19\% overestimate when only utterances of length 1-10 words
were considered.Comment: 10 pages, Latex source. To appear in Proc. ICSLP '9
- …