Let PāP1ā(Q) be a periodic point for a monic polynomial
with coefficients in Z. With elementary techniques one sees that the
minimal periodicity of P is at most 2. Recently we proved a generalization
of this fact to the set of all rational functions defined over Q
with good reduction everywhere (i.e. at any finite place of Q). The
set of monic polynomials with coefficients in Z can be
characterized, up to conjugation by elements in PGL2ā(Z), as the
set of all rational functions defined over Q with a totally ramified
fixed point in Q and with good reduction everywhere. Let p be a
prime number and let Fpā be the field with p elements. In the
present paper we consider rational functions defined over the rational global
function field Fpā(t) with good reduction at every finite place.
We prove some bounds for the cardinality of orbits in Fpā(t)āŖ{ā} for periodic and preperiodic points.Comment: arXiv admin note: substantial text overlap with arXiv:1403.229