premise: Two bikers a riding along a street in a marathon as the passersby clap for them.
hypothesis: Two bikers compete in a marathon for a charity.
explanation_1: Marathon is conducted for many purposes, not only for charity.
explanation_2: It is possible for bikers to ride in a marathon without competing against each other.  Not every marathon is for a charity.
explanation_3: You can not infer they are in a marathon.
premise_logic: exists s1 x5.(n_clap(x5) & a_passersby(s1) & Theme(s1,x5) & all x1.((n_thing(x1) & n_riding(x1)) -> exists x2 x3 x4.(a_topic(x2) & in(x2,x4) & as(x4,x5) & for(x5,x1) & n_marathon(x4) & along(x2,x3) & n_street(x3) & for(x2,x1) & n_biker(x2) & card_eq_2(x2))))
hypothesis_logic: exists e1 x1 x2 x3.(for(e1,x3) & n_charity(x3) & in(e1,x2) & n_marathon(x2) & Actor(e1,x1) & v_compete(e1) & n_biker(x1) & card_eq_2(x1))