>>782
d(x,y)<ε
ρ(x)=inf{d(x,a)|a∈A}≦inf(d(x,y)+d(y,a)|a∈A}=d(x,y)+inf{d(y,a)|a∈A}<ε+ρ(y)
ρ(y)<ε+ρ(x)
|ρ(x)-ρ(y)|<ε
uniform continuous
x∈X-A
∀a∈A∃Ua∋x,Va∋a Ua∩Va=φ
∪Va⊃A:compact
a1,…,an∈A V=∪Vak⊃A
Wx=∩Uak:open Wx∩V=φ
X-A⊃X-V⊃Wx∋x
X-A:open
f^-1(φ)=φ,f^-1(R)=R
g^-1(φ)=φ,g^-1(R)=R
f^-1(Us)=Ug(s)
g^-1(Us)=(-∞,s-1] for s∈Z, (-∞,f(s)] otherwize