A boat floats near someone swimming in clear, blue water.
There was a boat in the lake.
You can not infer there is a boat.
exists e1 s1 s2 s3 x1 x2 x3 x4.(near(e1,x2) & in(x2,x4) & n_water(x4) & a_blue(s3) & Theme(s3,x4) & a_,(s2) & Theme(s2,x4) & a_clear(s1) & Theme(s1,x4) & Time(x2,x3) & n_swimming(x3) & n_person(x2) & Actor(e1,x1) & v_float(e1) & n_boat(x1))
exists p1 x1 x2.(n_lake(x2) & in(p1,x2) & exists x3.((x1 = x3) & n_boat(x3)))