. _:b19036009 . . _:b19035983 . _:b19035998 . _:b19036008 . _:b19035997 . _:b19036015 . _:b19035996 . _:b19036014 . _:b19036013 . _:b19035987 . . _:b19036012 . . _:b19035986 . . _:b19036019 . _:b19035985 . _:b19036003 . _:b19036018 . . "https://en.m.wikipedia.org/wiki/Level_set" . _:b19035984 . _:b19036002 . _:b19036017 . _:b19035991 . _:b19036001 . _:b19036016 . _:b19035990 . . _:b19036000 . _:b19035989 . . . . _:b19036007 . . . . _:b19035988 . _:b19036006 . _:b19036021 . . _:b19035995 . . _:b19036005 . . _:b19036020 . _:b19035994 . _:b19036004 . . . _:b19035993 . _:b19036011 . . . _:b19035992 . _:b19036010 . . . _:b19035999 . . .