(* Weak Axiom of Cost Minimization *)



efficOf[i_, j_, w_, x_] := (w[[j]].x[[i]])/(w[[j]].x[[j]])



eff[w_, x_, y_] := Map[Union,

    Table[If[y[[i]] <= y[[j]], Min[efficOf[j, i, w, x], 1], 1],

      {i, 1, Length[y]}, {j, 1, Length[y]}]]



costEfficiency[w_, x_, y_] := Map[Min, eff[w, x, y]]