20090207, 09:48  #1 
May 2004
2^{2}×7×11 Posts 
Return to failure functions
Old timers may perhaps recall my posts pertaining to failure functions. I now propose to present in a sysematic manner the definitions pertaining to
the above relevant to the following areas of number theory: a) Polynomial functions b) exponential functions and Diophantine equations. Polynomial functions Let phi(x) be a function of x ( x belongs to Z). Let the definition of a failure be a composite number. Then x = psi(x_0) = x_0 + k.phi(x_0) generate values of x which enable phi(x) to generate only failures (composite numbers). Here x_0 is a specific value of x and k belongs to N. Let me give a simple numerical illustration. Let phi(x) = x^2 + x + 15. When x =1 phi(x) = 17. x = psi(1) = 1 + k.17 generates values of x which when substituted in phi(x) yield only composite numbers (each a multiple of 17). Note: when phi(x) is composite each factor contributes a failure function. A.K.Devaraj (To be continued) 
20090207, 13:08  #2  
May 2004
464_{8} Posts 
Return to failure functions
Quote:
To continue: Exponential functions: Let phi(x)= a^x + c where a,x and c belong to N, a and c being fixed. Let the definition of a failure again be a composite number. Then x = psi(x_0) = x_0 + k.Eulerphi(phi(x_0)) is a failure function since phi(psi(x_0)) generates only failures ( composite numbers). Note: phi(psi(x_0)) are multiples of phi(x_0). Numerical illustration: Let phi(x) = 2^n + 7. When x =1, phi(1) = 9 and x = psi(1) = 1 + k.Eulerphi(9) is a failure function generating values of x such that phi(x) are failures (composites) being multiples of 9. When x=2, phi(2) = 11and the relevant failure function is x = psi(2) = 2 + k.10. i.e. phi(x) for values of x = 2, 12, 22....generates only failures (all multiples of 11). Pl note a) whenever phi(x) is composite each factor contributes a failure function and b) this is a generalisation of Fermat's theorem. (To be continued) A.K.Devaraj Last fiddled with by devarajkandadai on 20090207 at 13:11 

20090208, 04:03  #3 
May 2004
2^{2}·7·11 Posts 
Return to failure functions
c. Diohantine equations
Perhaps the best intro to the role of failure functions in solving Diophantine equations wd be my paper " A Theorem a la Ramanujan" on www.crorepatibaniye.com\failurefunctions A.K.Devaraj (To be continued) 
20090208, 14:54  #4 
Nov 2003
2^{2}·5·7·53 Posts 
Your post should be retitled "The Failure Returns"

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