I remember before that ET said {and, or, not} are a universal set of logic operators:
If nand can make not, and, or and not, and, or can make all other logic operators, that means nand can also make all other operators. I bet nor can make all other operators too.
To answer the first question I think a small set of universal logic operators is {nand}. Idk if “operators” in the first question means that I have to include two operators.
For the second question, I had to look up what a subset is. I think you can make the universal sets {and, not} or {or, not} from {and, not, or}.
I read ahead and found this question:
nand isn’t missing anything as a universal set cuz it can make nor too.