I had no idea where to post questions related to Boolean algebra and logic gates, so I thought that the logic section would be good enough. If not please move it. Anyways are there any parameters that a gate must satisfy to be a universal gate. NAND and NOR gates are universal gates while others are not. Whats so special in these gates that make them universal. So are there any parameters such that we look at them and can judge if a gate is universal or not?