A New Frontier in Computation--Computation with Information Described in Natural Language
Lotfi A. Zadeh
What is computation with information described in natural language? A simple example: I am planning to drive from Berkeley to Santa Barbara, with a stopover for lunch in Monterey. It is about 10 am. It will probably take me about two hours to get to Monterey and about an hour to have lunch. From Monterey, it will probably take me about five hours to get to Santa Barbara. What is the probability that I will arrive in Santa Barbara before about six pm?
Computation with information described in natural language, or NL-Computation for short, is a problem of intrinsic importance because much of human knowledge is described in natural language. Existing natural language techniques do not address the problem of NL-Computation.
Our approach to NL-Computation centers on what is referred to as generalized-constraint-based computation, or GC-Computation for short. A generalized constraint is expressed as X isr R, where X is the constrained variable, R is a constraining relation and r is an indexical variable which defines the way in which R constrains X.
NL-Computation involves three modules: (a) Precisiation module; (b) Protoform module; and (c) Computation module. The meaning of an element of a natural language, NL, is precisiated through translation into GCL and is expressed as a generalized constraint. An object of precisiation, p, is referred to as precisiend, and the result of precisiation, p*, is called a precisiand. The Protoform module serves the function of abstraction and summarization. The Computation module is a collection of protoformal deduction rules, with a rule having two parts: symbolic and computational. These rules are employed to compute an answer to a query.
The generalized-constraint-based computational approach to NL-Computation opens the door to a wide-ranging enlargement of the role of natural languages in scientific theories. Particularly important application areas are decision-making with information described in natural language, economics, systems engineering, risk assessment, qualitative systems analysis, search, question-answering, and theories of evidence.