P " ƒérie d9exer™i™es n¦PF sx„iq‚e„syxF ixer™i™e I X ‚estri™tion

X
Aσ X A ⊂X
A∩ A := {A∩B B ∈ A} σ A
A∩ A ⊂ A A∈ A A∩ A =
P(A)∩ A
Y f :X→Y
f|A:A→Y
(An)n∈NX X =
∪n∈NAnn∈NAn∈ A f:X→Y
n∈Nf|An:An→Y f
(X, A)
A X X0Y
f:X→R
A χA:X→R
f:X0→R
ARA
χA:R→R
f:X0→Y f
σ X0
f:X0→Y σ
X0
R
MER
E
ECE
E EC
R=E∪EC
MσR
RM
σ6=
σ
σ
E
R R
fR R f
f
gnf

fR R f
f
f