Concurrent Parsing In Programmable Logic Array (PLA-) Nets Problems And Proposals

This contribution attempts a conceptual and practical introduction into the principles of wiring or constructing special machines for language processing tasks instead of programming a universal machine. Construction would in principle provide higher descriptive adequacy in computationally based linguistics. After all, our heads do not apply programs on stored symbol arrays but are appropriately wired for understanding or producing language. Introductor~ Remarks i. For me, computational linguistics is not primarily a technical discipline implementing performance processes for independently defined formal structures of linguistic competence. Computational linguistics should be a foundational discipline: It should be related to processoriented linguistics as the theory of logical calculi is to formal linguistics (e.g. generative linguistics, Montague-grammars etc.). 2. As it stands, computational linguistics does not yet meet the requirements for a foundational discipline. Searle's arguments against the claims of artificial intelligence apply fully to computational linguistics: Programmed solutions of tasks may execute the task satisfactorily without giving a model of its execution in the organism. Our intentional linguistic acts are caused by and realized in complicated concurrent processes occcurring in networks of neurons and are experienced as spontaneous. This also applies to special cases such as the recognition of syntactic structure (parsing). These processes are not controlled and executed by central processor units. 3. Computational linguistics must meet the challenge to satisfy the double criterion of descriptive adequacy: Adequacy in the description of what human beings do (e.g. parsing) and adequacy in the description of ho__~w they do it (namely by spontaneous concurrent processes corresponding to unconscious intuitive understanding). It must try to meet the challenge to provide the foundations for a descriptively and explanatorily adequate process-oriented linguistic, even when it is clear that the presently available conceptual means for describing complicated concurrent processes mainly the elements of computer architecture are far less understood than programming theory and programming technique. 4. Note: It does not stand to question that there is any problem which, in principle, could not be solved by programming. It is simply the case that almost all solutions are descriptively inadequate for representing and understanding what goes on in human beings even where they provide an adequate representation of input output relations and would thus pass Turing's test. 5. In my opinion, the main features to be realized in more adequate computational systems are concurrency of localized operations (instead of centrally controlled sequential processes), and signal processing (instead of symbol manipulation). These features cannot be represented by a program on an ordinary von Neumann machine since this type of machine is by definition a sequential,centrally controlled symbol manipulator. This does not exclude that programs may simulate concurrent processes. For instance, programs for testing gate array designs are of this kind. But simulating programs must clearly separate the features they simulate from the features which are only specific for their sequential operation. Electronic worksheet programs (in particular those used for planning and testing of gate arrays) are appropriate simulators of this type since their display on the monitor shows the network and signal flow whereas the specifics of program execut/on are concealed from the user. 6. How should computational linguistics be developed to meet the challenge? I think that the general method has already been specified by yon Neumann and Burks in their attempt to compare behavior and structure in computers and brains in terms of cellular automata. They have shown in this context that we have always two alternatives: Solutions for tasks can be realized by programs to be executed on an universal centrally controlled (von Neumann) machine, or they can be realized by constructing a machine. Since ordinary i.e. non-cellular-von-Neumann machines are sequential, realization of concurrent processes can only be approached by constructing (or describing the construction of such a system, e.g. the brain).