problem-set/pelletier/p39.desc created : 08/17/89 revised : 08/17/89 Natural Language Description: Full Predicate Logic (without Identity and Functions). Problem #39. Russell's paradox: there is no `Russell set' (a set which contains exactly those sets which are not members of themselves) -(Ex)(Ay)(Fyx <-> -Fyy). Versions: p39.in - declarative representation. created by : From Pelletier paper, 1986. verified for ITP : untested. translated for OTTER by : caw. verified for OTTER : 08/17/89.