is the set F = {A|A or A^c is finite} over R a sigma algebra?
define
My anwser: Yes as
a) if empty set = then A = which belongs to F
b) WLOG if A is finite let B = is uncoutnable but is fintire thus B belongs in F.
c) a union of finite sets is finite thus belong in F
My anwser: Yes as
a) if empty set = then A = which belongs to F
b) WLOG if A is finite let B = is uncoutnable but is fintire thus B belongs in F.
c) a union of finite sets is finite thus belong in F