We show, under weaker assumptions than in the previous literature, that a
perpetual optimal stopping game always has a value. We also show that there
exists an optimal stopping time for the seller, but not necessarily for the
buyer. Moreover, conditions are provided under which the existence of an
optimal stopping time for the buyer is guaranteed. The results are illustrated
explicitly in two examples.Comment: Published at http://dx.doi.org/10.1214/105051606000000204 in the
Annals of Applied Probability (http://www.imstat.org/aap/) by the Institute
of Mathematical Statistics (http://www.imstat.org