match u,v,w with
    | (u,w,v) when u = "" && v = "" -> (float_of_int(H.find wf w)) /. (float_of_int(_N +_V))
    | (u,w,v) when v = "" -> float_of_int(H.find wpf (u,w)) /. (float_of_int(H.find wf u) +. float_of_int(_V))
    | (u,w,v) when u = "" -> (float_of_int(H.find wf w) /. float_of_int(_N +_V)) *. (float_of_int(H.find wpf (w,v)) /. ((float_of_int(H.find wf w) +. float_of_int(_V)))
    | (u,w,v) ->  0.2