Proving that a given gate is universal The question is: Given gate called NEW has 4 inputs and 1 output NEW(w,x,y,z)=zy(w+z) Is NEW is Universal logic gate? I found that the gate is not universal because I can't create `NOT` gate with it. How should I prove it? thanks

Show that $NEW(1,1,1,1)=1$, and then use induction to show that no matter $NEW$ gates you string together, you'll always end up with $1$ on the output if all inputs are $1$