Universal differential equation

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A universal differential equation (UDE) is a non-trivial differential algebraic equation with the property that its solutions can approximate any continuous function on any interval of the real line to any desired level of accuracy.

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Precisely, a (possibly implicit) differential equation is a UDE if for any continuous real-valued function and for any positive continuous function there exist a smooth solution of with for all . [1]

The existence of an UDE has been initially regarded as an analogue of the universal Turing machine for analog computers, because of a result of Shannon that identifies the outputs of the general purpose analog computer with the solutions of algebraic differential equations. [1] However, in contrast to universal Turing machines, UDEs do not dictate the evolution of a system, but rather sets out certain conditions that any evolution must fulfill. [2]

Examples

and , whose solutions are of class for n > 3.
, where n > 3.

See also

References

  1. 1 2 3 Rubel, Lee A. (1981). "A universal differential equation". Bulletin of the American Mathematical Society. 4 (3): 345–349. doi: 10.1090/S0273-0979-1981-14910-7 . ISSN   0273-0979.
  2. 1 2 3 Pouly, Amaury; Bournez, Olivier (2020-02-28). "A Universal Ordinary Differential Equation". Logical Methods in Computer Science. 16 (1). arXiv: 1702.08328 . doi:10.23638/LMCS-16(1:28)2020. S2CID   4736209.
  3. Duffin, R. J. (1981). "Rubel's universal differential equation". Proceedings of the National Academy of Sciences. 78 (8): 4661–4662. Bibcode:1981PNAS...78.4661D. doi: 10.1073/pnas.78.8.4661 . ISSN   0027-8424. PMC   320216 . PMID   16593068.
  4. Briggs, Keith (2002-11-08). "Another universal differential equation". arXiv: math/0211142 .