Comment Comment by tromp Can it solve retrograde problems too? Let's ask it where the missing White King is in Smullyan's famous problem - - - - - - - - - - - - - r - b - - B - - - - - - - - - - - - - - k - - with White Ba4 and Black Kd1 Rb5 Bd5 and explain why. parent tromp 3 years ago