To RCS & Baker: As far as I understood, they thought the chlorobenzene was probably real, not due to contamination & processing, because they'd tested other rocks too and not seen it. But I do not know. Mars evidently pretty weird place with perchlorate all over. Perchlorates and chlorates would never survive on Earth for geological time scales. Didn't they already know about the perchlorates from previous (viking) lander? (And I must say I find the notion of using perchlorate as rocket fuel on Earth, disturbing for pollution reasons.) Robert Zubrin in some amusing book proposed a plan to travel to mars with a big hydrogen tank, then from martian CO2 synthesize methane and oxygen as fuel you would then use to take off & return to Earth. His ship carried a nuclear reactor to mars for power. He actually built & tested a chemical reactor to carry out the methane synthesis. To Latto: A = [-x/2, x/2], B = [2,3] the intersection of A with B is 0, then a linear function of x, then 1. Oh, I see, the last two parts are convex, but not the first two parts. Well, I guess I was only thinking of the function of x starting at the least x for which we get a nonzero volume. You & Veit both made some interesting suggestions about good conjectures, but I do not know their answers.