showTV (ProbTV a b c     ) = "(ptv "++show a++" "++show b++" "++show c++")"
showTV (ProbTV a b c     ) = "(ptv "++show a++" "++show b++" "++show c++")"
showTV (ProbTV a b c     ) = "(ptv "++show a++" "++show b++" "++show c++")"