A group of people standing on the lawn in front of a building.
There is at least one guy standing in front of the building
A group does not automatically indicate a mixture of the sexes. A guy or girl might be part of larger group made up solely of the same sex. To indicate that there is at least one guy tells the reader that the group is comprised mostly of the opposite sex.
exists e1 x1 x2 x3 x4 x5 x6.(n_lawn(x4) & a_topic(x1) & of(x1,x2) & in(e1,x5) & of(x5,x6) & n_building(x6) & n_front(x5) & on(e1,x4) & Actor(e1,x3) & v_stand(e1) & (x2 = x3) & n_people(x2) & n_group(x1))
exists p1 x1 x5.(n_building(x5) & exists s1 x2 x3 x4.(at(x1,x2) & in(x2,x4) & of(x4,x5) & n_front(x4) & r_most(s1) & a_least(s1) & Theme(s1,x2) & n_standing(x2) & of(x2,x3) & n_guy(x3) & card_eq_1(x2)))