premise: A man is navigating a boat.
hypothesis: A man is steering a large yacht down the lake.
explanation_1: Not every boat is a yacht, just because he is navigating the boat does not mean it is down the lake.
explanation_2: The man navigating may be different from the man steering. The boat may not be a large yacht and this sentence does not indicate that the boat is on a lake.
explanation_3: There are many types of boats, doesn't mean it was a large yacht, he could also be navigating in the ocean
premise_logic: exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_navigate(e1) & n_boat(x2) & n_man(x1))
hypothesis_logic: exists e1 s1 x1 x2 x3.(n_lake(x3) & Theme(e1,x2) & Actor(e1,x1) & v_steer(e1) & down(x2,x3) & n_yacht(x2) & a_large(s1) & Theme(s1,x2) & n_man(x1))