Suppose S is the smallest ΓΖ-algebra on R containing {(r,s] : r,s Γ’ΛΛ Q}. Prove that S is the collection of Borel subsets of R. Suppose S is the smallest ΓΖ-algebra on R containing {(r,n] : r Γ’ΛΛ Q, n Γ’ΛΛ Z}. Prove that S is the collection of Borel subsets of R. Suppose S is the smallest ΓΖ-algebra on R containing {(r,r + 1) : r Γ’ΛΛ Q}. Prove that S is the collection of Borel subsets of R. Suppose S is the smallest ΓΖ-algebra on R containing {[r,0) : r Γ’ΛΛ Q}. Prove that S is the collection of Borel subsets of R.