In this paper, we generalize the polar transforms of spacelike isothermic
surfaces in Q14β to n-dimensional pseudo-Riemannian space forms Qrnβ. We
show that there exist cβpolar spacelike isothermic surfaces derived from a
spacelike isothermic surface in Qrnβ, which are into Srn+1β(c),
Hrβ1n+1β(c) or Qrnβ depending on c>0,<0, or =0. The cβpolar
isothermic surfaces can be characterized as generalized Hβsurfaces with null
minimal sections. We also prove that if both the original surface and its
cβpolar surface are closed immersion, then they have the same Willmore
functional. As examples, we discuss some product surfaces and compute the
cβpolar transforms of them. In the end, we derive the permutability theorems
for cβpolar transforms and Darboux transform and spectral transform of
isothermic surfaces.Comment: 12 pages, to appear in J. Geom. Ph