Find!
x1=c1=z2 laughs about x2=z1 (abstract) in property/aspect x3=z3; x1=c1=z2 is amused about x2=z1 (abstract) amusing in property/aspect x3=z3 which causes x1=c1=z2 to laugh.
See also: cmila (to laugh, not neccessarly because of amuement)