We establish the eventual periodicity of the spectrum of any monadic second-order formula where (i) all relation symbols, except equality, are unary, and (ii) there is only one function symbol and that symbol is unary. Eighteenth Annual IEEE Symposium on Logic in Computer Science (LICS 2003) Microsoft Research, One Microsoft Way, Redmond, WA 98052 Publication 536, partially supported by US–Isra...