R(R)= R∪Ix = { & lt； a，a & gt，& ltb，b & gt，& ltc，c & gt，& lta，b & gt，& ltb，c & gt，& ltc，a & gt}

S(R)=R ∪ R (inverse) = {

S(R)=R( 1 order) ∪ r (order 2) ∪ r (order 3) ... = {< a, b>,<b, a>,<b, c>},<c, b>.

R( 1 order) = r = {

R (second order) = {

R (third order) = {

R (fourth order) = {

Therefore: s (r) = {

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