Kuhn-Tucker mutiplier is defined by Kuhn-Tucker condition, which is a necessary condition for maximum or minimum point.
the maximization problem with inequlity constraints:
MAX f(x) s.t. g(x)<=b , where f,g,x,b can be vectors.
If x is the local maximizer of the problem, we have:
df/dx=λ dg/dx
λ(g(x)-b)=0
where λ is the Kuhn-Tucker mutiplier.