Zd
dk.k1
Rdkxk1=
d
X
i=1
|xi|x= (x1, ..., xd)∈Rdx∈ZdV(x)
Zdx V (x) = {y∈Zd;ky−xk1= 1}
x2d
AZdI(A)x∈A V (x)⊂A ∂A
A I(A)A=ZdI(A) = A ∂A =∅A
<2d I(A) = ∅∂A =A
f:A−→ RI(A)x∈I(A)
f(x) = 1
2dX
y∈V(x)
f(y).
(Ω,A, P )
Zd
d= 1
f:Z−→ R Z
k f(k+ 2) −2f(k+ 1) + f(k) = 0
Z
f:Z∗−→ RI(Z∗)
I(Z∗)
d
f:Zd−→ R Zd
k∈Zd`∈V(k)f(`)≤2d f(k)
k∈Zd`∈Zdf(`)≤(2d)k`−kk1f(k)
k∈Zdf(k)=0 f
f ` ∈Zd|ln(f(`)) −ln(f(k))| ≤
k`−kk1ln(2d)
f:Zd−→ R Zdf
dN∗Rd(e[1], ..., e[d])
∀(i, j)∈ {1, ..., d}2, e[i]j=(1i=j;
0i6=j.
(Xn)n∈N
Dd={−d, −d+ 1, ..., −1,1, ..., d −1, d}
(Yn)n∈N
Y0= 0,∀n∈N, Yn+1 =Yn+sign(Xn)e[|Xn|],
k∈N∗sign(k) = k
|k|.