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APPROXIMATE PEXIDERIZED EXPONENTIAL TYPE FUNCTIONS

  • Lee, Young-Whan (Department of Computer Hacking and Information Security, College of Natural Science, Daejeon University)
  • Received : 2012.04.05
  • Accepted : 2012.05.14
  • Published : 2012.05.31

Abstract

We show that every unbounded approximate Pexiderized exponential type function has the exponential type. That is, we obtain the superstability of the Pexiderized exponential type functional equation $$f(x+y)=e(x,y)g(x)h(y)$$. From this result, we have the superstability of the exponential functional equation $$f(x+y)=f(x)f(y)$$.

Keywords

References

  1. J. Baker: The stability of the cosine equations. Proc. Amer. Math. Soc. 80 (1980), 411-416. https://doi.org/10.1090/S0002-9939-1980-0580995-3
  2. J. Baker, J. Lawrence & F. Zorzitto: The stability of the equation f(x + y) = f(x) + f(y). Proc. Amer. Math. Soc. 74 (1979), 242-246.
  3. G.L. Forti: Hyers-Ulam stability of functional equations in several variables. Aequationes Math. 50 (1995), 146-190.
  4. R. Ger: Superstability is not natural. Rocznik Naukowo-Dydaktyczny WSP Krakkowie, Prace Mat. 159 (1993), 109-123.
  5. D.H. Hyers: On the stability of the linear functional equation. Proc. Natl. Acad. Sci. 27 (1941), 222-224. https://doi.org/10.1073/pnas.27.4.222
  6. D.H. Hyers & Th.M. Rassias: Approximate homomorphisms. Aequatioues Math. 44 (1992), 125-153. https://doi.org/10.1007/BF01830975
  7. D.H. Hyers, G. Isac & Th.M. Rassias: Stability of functional equations in several variables. Birkhauser-Basel-Berlin (1998).
  8. K.-W. Jun, G.H. Kim & Y.W. Lee: Stability of generalized gamma and beta functional equations. Aequationes Math. 60 (2000), 15-24 https://doi.org/10.1007/s000100050132
  9. S.-M. Jung: On the general Hyers-Ulam stability of gamma functional equation. Bull. Korean Math. Soc. 34 (1997), no. 3, 437-446.
  10. G.H. Kim & Y.W. Lee: Approximate gamma-beta type functions. Nonlinear Analysis. 71 (2009), e1567-e1574. https://doi.org/10.1016/j.na.2009.01.206
  11. G.H. Kim & Y.W. Lee: The stability of the beta functional equation. Babes-Bolyai Mathematica XLV (2000), no. 1, 89-96.
  12. Y.W. Lee: On the stability of a quadratic Jensen type functional equation. J. Math. Anal. Appl. 270 (2002) 590-601. https://doi.org/10.1016/S0022-247X(02)00093-8
  13. Y.W. Lee: The stability of derivations on Banach algebras. Bull. Institute of Math. Academia Sinica 28 (2000), 113-116.
  14. Y.W. Lee: Superstability and stability of the pexiderized multiplicative functional equation. J. Inequal. and Appl. (2010) Article ID 486325, 1-15.
  15. Th.M. Rassias: On the stability of the linear mapping in Banach spaces. Proc. Amer. Math. Soc. 72 (1978), 297-300. https://doi.org/10.1090/S0002-9939-1978-0507327-1
  16. Th.M. Rassias: The problem of S.M. Ulam for approximately multiplication mappings. J. Math. Anal. Appl. 246 (2000), 352-378. https://doi.org/10.1006/jmaa.2000.6788
  17. S.M. Ulam: Problems in Modern Mathematics. Proc. Chap. VI. Wiley. NewYork, 1964.