From Wikipedia, the free encyclopedia
This article is within the scope of WikiProject Mathematics , a collaborative effort to improve the coverage of mathematics on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.Mathematics Wikipedia:WikiProject Mathematics Template:WikiProject Mathematics mathematics Mid This article has been rated as Mid-priority on the project's priority scale .
In Section "Mathematical theorem", why the unwieldy notation with negated functions
p
∗
=
inf
x
∈
X
{
f
(
x
)
+
g
(
A
x
)
}
{\displaystyle p^{*}=\inf _{x\in X}\{f(x)+g(Ax)\}}
d
∗
=
sup
y
∗
∈
Y
∗
{
−
f
∗
(
A
∗
y
∗
)
−
g
∗
(
−
y
∗
)
}
{\displaystyle d^{*}=\sup _{y^{*}\in Y^{*}}\{-f^{*}(A^{*}y^{*})-g^{*}(-y^{*})\}}
instead of
p
∗
=
inf
x
∈
X
{
f
(
x
)
+
g
(
A
x
)
}
{\displaystyle p^{*}=\inf _{x\in X}\{f(x)+g(Ax)\}}
d
∗
=
inf
y
∗
∈
Y
∗
{
f
∗
(
A
∗
y
∗
)
+
g
∗
(
−
y
∗
)
}
{\displaystyle d^{*}=\inf _{y^{*}\in Y^{*}}\{f^{*}(A^{*}y^{*})+g^{*}(-y^{*})\}}
? — Preceding unsigned comment added by 132.185.132.13 (talk ) 10:12, 29 April 2014 (UTC) [ reply ]
Answering my own (stupid) question:
Because
sup
y
∗
∈
Y
∗
{
−
f
∗
(
A
∗
y
∗
)
−
g
∗
(
−
y
∗
)
}
=
−
inf
y
∗
∈
Y
∗
{
f
∗
(
A
∗
y
∗
)
+
g
∗
(
−
y
∗
)
}
{\displaystyle \sup _{y^{*}\in Y^{*}}\{-f^{*}(A^{*}y^{*})-g^{*}(-y^{*})\}=-\inf _{y^{*}\in Y^{*}}\{f^{*}(A^{*}y^{*})+g^{*}(-y^{*})\}}
which is equally unwieldy. — Preceding unsigned comment added by 132.185.132.13 (talk ) 11:08, 29 April 2014 (UTC) [ reply ]
Is there a reason "max" rather than "sup" is used in the lede? Jess_Riedel (talk ) 03:07, 2 July 2017 (UTC) [ reply ]
Thanks for noticing that. It was left over from a much earlier version which had min/max. Encyclops (talk ) 18:28, 3 July 2017 (UTC) [ reply ]