(Pre)images of intervals
In this file we prove a bunch of trivial lemmas like “if we add a
to all points of [b, c]
,
then we get [a + b, a + c]
”. For the functions x ↦ x ± a
, x ↦ a ± x
, and x ↦ -x
we prove
lemmas about preimages and images of all intervals. We also prove a few lemmas about images under
x ↦ a * x
, x ↦ x * a
and x ↦ x⁻¹
.
Preimages under x ↦ a + x
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Preimages under x ↦ x + a
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Preimages under x ↦ -x
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Preimages under x ↦ x - a
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Preimages under x ↦ a - x
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Images under x ↦ a + x
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Images under x ↦ x + a
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Images under x ↦ -x
Images under x ↦ a - x
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Images under x ↦ x - a
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Multiplication and inverse in a field
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theorem
set.preimage_const_mul_Ioo_of_neg
{k : Type u}
[linear_ordered_field k]
(a b : k)
{c : k} :
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theorem
set.preimage_const_mul_Ioc_of_neg
{k : Type u}
[linear_ordered_field k]
(a b : k)
{c : k} :
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theorem
set.preimage_const_mul_Ico_of_neg
{k : Type u}
[linear_ordered_field k]
(a b : k)
{c : k} :
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theorem
set.preimage_const_mul_Icc_of_neg
{k : Type u}
[linear_ordered_field k]
(a b : k)
{c : k} :
theorem
set.image_mul_left_Icc'
{k : Type u}
[linear_ordered_field k]
{a : k}
(h : 0 < a)
(b c : k) :
The image under inv
of Ioo 0 a
is Ioi a⁻¹
.