premise: A line of rollerbladers crouch down aerodynamically
hypothesis: A group of rollerbladers are crouching.
explanation_1: A group is synonymous with a line.
explanation_2: A line of rollerbladers is a group.  People who crouch down is crouching.
explanation_3: Line of rollerbladers is a group of rollerbladers, and are crouching is a rephrasing of crouch down aerodynamically.
premise_logic: exists e1 s1 s2 x1 x2.(a_aerodynamically(s2) & Manner(e1,s2) & a_down(s1) & Manner(e1,s1) & Actor(e1,x1) & v_crouch(e1) & of(x1,x2) & n_rollerblader(x2) & n_line(x1))
hypothesis_logic: exists e1 x1 x2.(Actor(e1,x1) & v_crouch(e1) & of(x1,x2) & n_rollerblader(x2) & n_group(x1))