%0 Journal Article %A Silverman, Joseph H. %T The field of definition for dynamical systems on $\mathbb {P}^1$ %J Compositio Mathematica %D 1995 %P 269-304 %V 98 %N 3 %I Kluwer Academic Publishers %U http://archive.numdam.org/item/CM_1995__98_3_269_0/ %G en %F CM_1995__98_3_269_0