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Discrete mathematical homomorphism
The first chapter is the basis of set theory.

1. Let S = {2, a, {3}, 4}, R ={{a}, 3,4, 1}, and point out which of the following statements is right and which is wrong. {a}? s,{a}? r,{a,4,{3}}? s,{{a}, 1,3,4}? R,R=S,{a}? s,{a}? R,R,{{a}}? r? e,{? }? s,R,{{3},4} .

Solution: {a}? s? ,{a}? r? ,{a,4,{3}}? s? ,{{a}, 1,3,4 }? r? ,R = S? ,{a}? s? ,{a}? r? ,R? ,{{a}}? r? e? ,{? } ? s? ,R? , {{3},4 }?

Write the power set of the following set.

{a,{b}},{ 1,? },{X,Y,Z}

Solution: Let A={a, {b}}, then? (A)={? 、{a}、{{b}}、{a、{ b } } }

Let B={ 1,? }, and then what? (B)= {? ,{ 1},{? },{ 1,? }};

Let C={X, y, Z}, then? (C)= {? 、{X}、{Y}、{Z}、{X,Y}、{X,Z}、{Y,Z }、{X,Y,Z } }