Week 5 Tutorial
Fix an irrational number
α
and put
T
(
x
)
=
x
+
α
mod
1
for all
x
∈
[
0
,
1
)
.
Is there
n
∈
N
with
0
<
T
n
(
0
)
<
1
4
?
Is there
n
∈
2
N
with
0
<
T
n
(
0
)
<
1
4
?
Is there
n
∈
2
N
+
1
with
0
<
T
n
(
0
)
<
1
4
?
Is there
0
≤
n
≤
3
with
0
<
T
n
(
0
)
<
1
4
?
Is there
0
≤
n
≤
7
1000
with
0
<
T
n
(
0
)
<
1
4
?
Is there
0
≤
n
≤
3
with
−
1
8
<
T
n
(
0
)
<
1
8
?
Is there
0
≤
n
≤
7
1000
with
−
1
8
<
T
n
(
0
)
<
1
8
?
Give an example of a set
E
⊂
[
0
,
1
)
with
lim
N
→
∞
1
N
∑
n
=
0
N
−
1
1
E
(
T
n
(
x
)
)
=
0
and
λ
(
E
)
=
1
.
Give an example of a set
E
⊂
[
0
,
1
)
for which
lim
N
→
∞
1
N
∑
n
=
0
N
−
1
1
E
(
T
n
(
x
)
)
does not exist.
A continuous function
f
:
[
0
,
1
)
→
[
0
,
∞
)
is such that
lim
N
→
∞
1
N
∑
n
=
0
N
−
1
f
(
T
n
(
x
)
)
=
0
holds. What can you say about
f
?