Ã
n-1
X = (0, 1) An = (0, ) n " N {An} Ã({An})
n
X = R A1 = {(n, n + 1) : n " Z} A2 = {[n, n + 1] : n " Z}
Ã(A1) ‚" Ã(A2) Ã(A1) ƒ" Ã(A2).
Bn B Ã Rn
B
R R
[a, b] (a, b] [a, b)
Ã({(a, b) : a, b " R, a < b}) = B
R
à R
à R
Ã1 = Ã({(a, b) : a, b " R, a < b}), Ã9 = Ã({(p, q) : p, q " Q, p < q}),
Ã2 = Ã({[a, b] : a, b " R, a < b}), Ã10 = Ã({[p, q] : p, q " Q, p < q}),
Ã3 = Ã({[a, b) : a, b " R, a < b}), Ã11 = Ã({[p, q) : p, q " Q, p < q}),
Ã4 = Ã({(a, b] : a, b " R, a < b}), Ã12 = Ã({(p, q] : p, q " Q, p < q}),
Ã5 = Ã({(-", a) : a " R}), Ã13 = Ã({(-", p) : p " R}),
Ã6 = Ã({(-", a] : a " R}), Ã14 = Ã({(-", p] : p " R}),
Ã7 = Ã({(a, ") : a " R}), Ã15 = Ã({(p, ") : p " R}),
Ã8 = Ã({[a, ") : a " R}), Ã16 = Ã({[p, ") : p " R}).
Ãi = Ãj 1 i < j 16