×

Dynamical recognizers: real-time language recognition by analog computers. (English) Zbl 0902.68098

Summary: We consider a model of analog computation which can recognize various languages in real time. We encode an input word as a point in \({\mathbb{R}}^{d}\) by composing iterated maps, and then apply inequalities to the resulting point to test for membership in the language. Each class of maps and inequalities, such as quadratic functions with rational coefficients, is capable of recognizing a particular class of languages. For instance, linear and quadratic maps can have both stack-like and queue-like memories. We use methods equivalent to the Vapnik-Chervonenkis dimension to separate some of our classes from each other: linear maps are less powerful than quadratic or piecewise-linear ones, polynomials are less powerful than elementary (trigonometric and exponential) maps, and deterministic polynomials of each degree are less powerful than their non-deterministic counterparts. Comparing these dynamical classes with various discrete language classes helps illuminate how iterated maps can store and retrieve information in the continuum, the extent to which computation can be hidden in the encoding from symbol sequences into continuous spaces, and the relationship between analog and digital computation in general. We relate this model to other models of analog computation; in particular, it can be seen as a real-time, constant-space, off-line version of Blum, Shub and Smale’s real-valued machines.

MSC:

68Q45 Formal languages and automata
Full Text: DOI

References:

[1] R. Bartlett, M. Garzon, Computational complexity of piecewise linear maps of the interval, Thèoret. Comput. Sci., submitted.; R. Bartlett, M. Garzon, Computational complexity of piecewise linear maps of the interval, Thèoret. Comput. Sci., submitted. · Zbl 0820.68082
[2] Berstel, J., Transductions and Context-Free Languages (1978), Teubner Studienbücher: Teubner Studienbücher Stuttgart · Zbl 0424.68040
[3] Blum, L.; Shub, M.; Smale, S., On a theory of computation and complexity over the real numbers: NP-completeness, recursive functions and universal machines, Bull. Amer. Math. Soc., 21, 1-46 (1989) · Zbl 0681.03020
[4] Blumer, A.; Ehrenfeucht, A.; Haussler, D.; Warmuth, M. K., Learning and the Vapnik-Chervonenkis dimension, J. ACM, 36, 4, 929-965 (1989) · Zbl 0697.68079
[5] Boasson, L.; Courcelle, B.; Nivat, M., The rational index: a complexity measure for languages, SIAM J. Comput., 10, 2, 284-296 (1981) · Zbl 0469.68083
[6] Book, R.; Greibach, S., Quasi-realtime languages, Math. Systems Theory, 4, 97-111 (1970) · Zbl 0188.33102
[7] Brandenburg, F. J., Intersections of some families of languages, (Proc. 13th ICALP. Proc. 13th ICALP, Lecture Notes in Computer Science, vol. 226 (1986), Springer: Springer Berlin), 61-68 · Zbl 0596.68057
[8] Casey, M., The dynamics of discrete-time computation, with application to recurrent neural networks and finite-state machine extraction, Neural Comput., 8, 6 (1996), to appear.
[9] Cherubini, A.; Citrini, C.; Reghizzi, S. C.; Mandrioli, D., QRT FIFO automata, breadth-first grammars and their relations, Theoret. Comput. Sci., 85, 171-203 (1991) · Zbl 0745.68069
[10] Koiran, P.; Cosnard, M.; Garzon, M., Computability properties of low-dimensional dynamical systems, Theoret. Comput. Sci., 132, 113-128 (1994) · Zbl 0821.68053
[11] F. Cucker, M. Matamala, On digital nondeterminism, Math. Systems Theory, to appear.; F. Cucker, M. Matamala, On digital nondeterminism, Math. Systems Theory, to appear. · Zbl 0868.68058
[12] Cucker, F.; Grigoriev, D., On the power of real Turing machines over binary inputs, NeuroCOLT Technical Report NC-TR-94-007 (1994)
[13] Das, S.; Giles, C. L.; Sun, G. Z., Using prior knowledge in an NNPDA to learn languages, Adv. Neural Inform. Process. Systems, 5, 65-72 (1993)
[14] Elman, J., Language as a dynamical system, (Port, R. F.; van Gelder, T., Mind as Motion: Explorations in the Dynamics of Cognition (1995), MIT Press: MIT Press Cambridge, MA)
[15] Garey, M. R.; Johnson, D. S., Computers and Intractability: A Guide to the Theory of NP-Completeness (1979), Freeman: Freeman New York · Zbl 0411.68039
[16] Giles, C. L.; Miller, C. B.; Chen, D.; Chen, H. H.; Sun, G. Z.; Lee, Y. C., Learning and extracting finite-state automata with second-order recurrent networks, Neural Comput., 2, 331-349 (1992)
[17] Goldberg, P. W.; Jerrum, M. R., Bounding the Vapnik-Chevonenkis dimension of concept classes parametrized by real numbers, Machine Learning, 18, 131-148 (1995) · Zbl 0831.68087
[18] Grädel, E.; Meer, K., (Proc. 27th Symp. on the Theory of Computing (1995)), 315-324 · Zbl 0968.68517
[19] Greibach, S. A., A note on undecidable properties of formal languages, Math. Systems Theory, 2, 1, 1-6 (1968) · Zbl 0157.01902
[20] Guckenheimer, J.; Holmes, P., Nonlinear Oscillations, Dynamical Systems, and Bifurcations of Vector Fields (1983), Springer: Springer Berlin · Zbl 0515.34001
[21] Hopcroft, J. E.; Ullman, J. D., Introduction to Automata Theory, Languages, and Computation (1979), Addison-Wesley: Addison-Wesley Reading, MA · Zbl 0196.01701
[22] Knuth, D. E., Seminumerical Algorithms (1981), Addison-Wesley: Addison-Wesley Reading, MA · Zbl 0477.65002
[23] Koiran, P., Computing over the reals with addition and order, Theoret. Comput. Sci., 133, 35-47 (1994) · Zbl 0822.68028
[24] Koiran, P., A weak version of the Blum, Shub and Smale model, DIMACS Technical Report 94-10 (1994) · Zbl 0869.68049
[25] P. Koiran, C. Moore, Closed-form analytic maps in one and two dimensions can simulate Turing machines, Theoret. Comput. Sci., to appear.; P. Koiran, C. Moore, Closed-form analytic maps in one and two dimensions can simulate Turing machines, Theoret. Comput. Sci., to appear. · Zbl 0912.68033
[26] Leong, B. L.; Seiferas, J. I., New real-time simulations of multihead tape units, J. ACM, 28, 1, 166-180 (1981) · Zbl 0454.68033
[27] Liu, L.; Weiner, P., An infinite hierarchy of intersections of context-free languages, Math. Systems Theory, 7, 185-192 (1973) · Zbl 0257.68077
[28] Meer, K., Real number models under various sets of operations, J. Complexity, 9, 366-372 (1993) · Zbl 0782.68048
[29] Michaux, C., Differential fields, machines over the real numbers and automata, (Ph.D. thesis (1991), Université de Mons Hainaut, Faculte des Sciences) · Zbl 0638.03029
[30] Moore, C., Nonlinearity, 4, 199-230 (1991) · Zbl 0725.58013
[31] Moore, C., Generalized one-sided shifts and maps of the interval, Nonlinearity, 4, 727-745 (1991) · Zbl 0736.58020
[32] C. Moore, Smooth one-dimensional maps of the interval and the real line capable of universal computation, Santa Fe Institute Working Paper 93-01-001.; C. Moore, Smooth one-dimensional maps of the interval and the real line capable of universal computation, Santa Fe Institute Working Paper 93-01-001.
[33] Nilsson, U.; Hald, F., Her er en lille gris (1994), Gyldendal
[34] Papadimitriou, C. H., Computational Complexity (1994), Addison-Wesley: Addison-Wesley Reading, MA · Zbl 0557.68033
[35] Paradaens, J.; Vincke, R., A class of measures on formal languages, Acta Inform., 9, 73-86 (1977) · Zbl 0363.68098
[36] Pollack, J., The induction of dynamical recognizers, Machine Learning, 7, 227-252 (1991)
[37] Rosenberg, A. L., Real-time definable languages, J. ACM, 14, 645-662 (1967) · Zbl 0153.00902
[38] Siegelmann, H.; Sontag, E. D., Analog computation via neural networks, Theoret. Comput. Sci., 131, 331-360 (1994) · Zbl 0822.68029
[39] Steijvers, M.; Grünwald, P. D.G., A recurrent network that performs a context-sensitive prediction task, NeuroCOLT Technical Report NC-TR-96-035 (1996)
[40] in: Proc. 18th Annual Conf. Cognitive Science Society, Erlbaum, London, in press.; in: Proc. 18th Annual Conf. Cognitive Science Society, Erlbaum, London, in press.
[41] Warren, H. E., Lower bounds for approximation by nonlinear manifolds, Trans. Amer. Math. Soc., 133, 167-178 (1968) · Zbl 0174.35403
This reference list is based on information provided by the publisher or from digital mathematics libraries. Its items are heuristically matched to zbMATH identifiers and may contain data conversion errors. In some cases that data have been complemented/enhanced by data from zbMATH Open. This attempts to reflect the references listed in the original paper as accurately as possible without claiming completeness or a perfect matching.