离散数学:设A={1,2,3,4,5},R={|x∈A,y∈A且x-y=3},S={|x∈A,y∈A且x+y=3}试着求R,S,R*S,R^(-1),r(S),S(R)
问题描述:
离散数学:设A={1,2,3,4,5},R={|x∈A,y∈A且x-y=3},S={|x∈A,y∈A且x+y=3}
试着求R,S,R*S,R^(-1),r(S),S(R)
答
R = {,};
S = {,};
R*S = ∅(先S后R),或 {}(先R后S);(注:不知你的你的教材的定义是哪个先)
R^(-1) = {,};
r(S) = {,,,,,,};
s(R) = {,,,}.