10
The Proof
•
3 Steps
1.
Design
s
,
f
B
s.t.
A
²
f
B
iff
A
is an atomic
boolean algebra,
A
= (2
X
,
µ
)
Let EVEN
B
= (EVEN(|X|)
Æ
f
B
2.
Show that EVEN
B
2
(FO + <)
inv
3.
Prove (using EF-games) that EVEN
B
Ï
FO