Exercises 0.3 #4

I) Let E be a correspondence from U to X. If (s0, x0) ∈ (ED)C then there is a t0 ∈ T such that (t0, x0) ∈ ED and (s0, t0) ∈ C. And there is a u0 ∈ U such that (u0, x0) ∈ E and (t0, u0) ∈ D. So (s0, u0) ∈ DC and (s0, x0) ∈ E(DC). Thus (ED)C ⊂ E(DC). If (s1, x1) ∈ E(DC) then there is a u1 ∈ U such that (u1, x1) ∈ E and (s1, u1) ∈ DC. And there is a t1 ∈ T such that (t1, u1) ∈ D and (s1, t1) ∈ C. So (t1, x1) ∈ ED and (s1, x1) ∈ (ED)C. Thus E(DC) ⊂ (ED)C. Therefore (ED)C = E(DC).

II) To do

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