1For the Caesar cipher, it can be shown that {
c∣c 
} is actually a partition of = , and the relation ≡ defined by
m1 ≡ m2 iff ∃c(m1 c ∧ m2 c) is an equivalence relation.
1For the Caesar cipher, it can be shown that {c∣c } is actually a partition of = , and the relation ≡ defined by
m1 ≡ m2 iff ∃c(m1 c ∧ m2 c) is an equivalence relation.