Find the local maximum and minimum values and saddle point(s) of the function. If you have three dimensional graphing software, graph the function with a domain and viewpoint that reveal all the important aspects of the function. (Enter your answers as a comma-separated list. If an answer does not exist, enter DNE.)

f(x,y) =x⁴+y⁴4xy+2

local maximum value(s)=

local minimum value(s)=

saddle point(s)(x,y,f)=