lattice ordered group; affine completeness; direct product
In the paper it is proved that a nontrivial direct product of lattice ordered groups is never affine complete.
 J. Jakubík: Affine completeness of complete lattice ordered groups
. Czechoslovak Math. J. 45 (1995), 571–576. MR 1344522
 K. Kaarli and A. F. Pixley: Polynomial Completeness in Algebraic Systems
. Chapman-Hall, London-New York-Washington, 2000. MR 1888967