premise: A group of onlookers glance at a person doing a strange trick on her head.
hypothesis: A boy does a card trick.
explanation_1: A group is not a single boy
explanation_2: A person can be anyone not just a boy.  A trick can be anything not just a card trick.
explanation_3: A boy that does a card trick cannot be among the onlookers.
premise_logic: exists e1 s1 x1 x2 x3 x4 x5 x6 x7.(a_topic(x1) & Theme(e1,x6) & Actor(e1,x5) & v_do(e1) & on(x6,x7) & n_head(x7) & of(x7,x1) & n_female(x1) & n_trick(x6) & a_strange(s1) & Theme(s1,x6) & (x1 = x5) & at(x1,x4) & n_person(x4) & of(x1,x2) & n_glance(x2) & of(x2,x3) & n_onlooker(x3) & n_group(x1))
hypothesis_logic: exists e1 x1 x2 x3.(Theme(e1,x2) & Actor(e1,x1) & v_do(e1) & n_trick(x2) & of(x2,x3) & n_card(x3) & n_boy(x1))