Timeline for How to decide this function takes integer values?

7 events

when toggle format	what		by	license	comment
Jun 8, 2011 at 18:01	comment	added	Geoff Robinson		It's much nicer to outline a general strategy, of course, though each individual problem of this type probably leaves some room for ingenuity.
Jun 8, 2011 at 13:35	comment	added	Noam D. Elkies		By the way, here's a link to a one-page paper outlining an elementary proof of the uniqueness of the Hoffman-Singleton graph: math.harvard.edu/~elkies/Misc/hsgraph.pdf With a bit more care you can use this technique also to count the graph's symmetries (there are 252000). The group turns out to be isomorphic with $P\Sigma U_3({\bf F}_5)$, but that's considerably harder; Mathworld gives the reference Hafner, P. R. "The Hoffman-Singleton Graph and Its Automorphisms." J. Algebraic Combin. 18, 7-12, 2003.
Jun 8, 2011 at 13:29	comment	added	Noam D. Elkies		I don't see how Runge's theorem relates here - can you please explain? Note that the approximating polynomial must have rational coefficients; this technique won't let you solve $y^2 = 2x^4 - 1$.
Jun 8, 2011 at 13:27	history	edited	Noam D. Elkies	CC BY-SA 3.0	Fixed TeXo; added phrases about origin of problem
Jun 8, 2011 at 9:23	comment	added	Felipe Voloch		This seems related to Runge's theorem.
Jun 8, 2011 at 3:28	history	edited	Noam D. Elkies	CC BY-SA 3.0	Correct the question (x and f(x), not x and n); correct number of factors r of 2^36 3^12 to allow r<0
Jun 8, 2011 at 3:20	history	answered	Noam D. Elkies	CC BY-SA 3.0