f
f
f
IRf:I→R
I
∀x∈I, f(x)6= 0
∀y∈R,∃x∈I, f(x) = y
∃M∈R,∀x∈I, |f(x)|6M
∀x, y ∈I, x 6y⇒f(x)6f(y)
∀x, y ∈I, f(x) = f(y)⇒x=y
∀x∈I, f(x)>0⇒x60
f1, f2, f3R R
(∀j∈ {1,2,3})(∃a∈R), fj(a)=1
(∃j∈ {1,2,3})(∀a∈R), fj(a)=1
(∃a∈R)(∀j∈ {1,2,3}), fj(a) = 1
(∀a∈R)(∃j∈ {1,2,3}), fj(a)=1
A, B E
A∩X=B
X∈ P(E)
A∪X=B
A E A
f E {0,1}f(x) = 0 x /∈A f(x) = 1 x∈A
A B E f g
1−f
fg
f+g−fg
E F f :E→F
f g :F→E g ◦f=IdE
f g :F→E f ◦g=IdF
f g :F→E g ◦f=IdEf◦g=IdF
f:E→F g :F→E f ◦g◦f
f g
P(P({a})) a