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)

  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) = {,,,}.