“…For typical examples of one‐sided solutions derived using the principle of smooth fit, we refer to papers on Russian options due to Shepp and Shiryaev (, ). Villeneuve () gives sufficient conditions to have threshold optimal strategies, and Arkin () gives necessary and sufficient conditions for Itô diffusions with C 2 payoffs functions to have one‐sided solutions, whereas Arkin and Slastnikov () and Crocce and Mordecki () give also necessary and sufficient conditions in different and more general diffusion frameworks. For more general Markov processes, Christensen and Irle (), Christensen, Salminen, and Ta (), and Mordecki and Salminen () propose verification results for one‐sided solutions, but also for problems where the optimal stopping time is of the form …”