小中学校範囲の算数・数学の問題のスレ

rule[x_] := Module[{f},
f = (Not[MemberQ[x, 1]] && Not[MemberQ[x, 2]]) || (MemberQ[x, 1] && MemberQ[x, 2]);
If[f, MemberQ[x, 1] || MemberQ[x, 2], x === {}]
]

li = {{}, {1}, {2}, {1, 2}};
rule /@ li