problem-set/puzzles/truth.lies/mars_venus2.desc created : 08/08/88 revised : 08/17/89 Natural Language Description : Here's the situation: human observers in this exclusive club on Ganymede can't distinguish Martians from Venusians, males from females, except for the fact that Venusian women and Martian men always tell the truth and Venusian men and Martian women always lie. A says "I'm from Mars" B exclaims "That's not true!" A and B are married; are they a mixed couple? Versions : mars_venus2: Uses hyperresolution, paramodulation, and unit deletion. created : 08/08/88. verified for ITP : 08/08/88. translated for OTTER : caw. verified for OTTER : 08/17/89.