Duality pairing in Banach spaces












2












$begingroup$


Suppose we have a Banach space $X$ and its dual $X^{'}$. Then the duality pairing is often written
$$langle f,vrangle_{X^{'},X} = f(v)$$



for $f in X^{'}$ and $v in X$. But is it allowed to write



$$
langle v,frangle_{X,X^{'}}
$$

to mean $langle f,vrangle_{X^{'},X}$?



In the setting of a Hilbert space $H$, for a given linear operator $A:Hto H^{'}$, I saw $A$ being self-adjont is written as



$$
langle Av,urangle = langle v,Aurangle
$$



Does $langle v,Aurangle$ here actually mean $langle Au,vrangle= Au(v)$?










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$endgroup$












  • $begingroup$
    It's just a convention, there's no mathematics reason why you can only write $langle v,frangle$ but not $langle f,vrangle$ and vise versa. You just need to be consistence.
    $endgroup$
    – BigbearZzz
    Jan 17 at 19:03


















2












$begingroup$


Suppose we have a Banach space $X$ and its dual $X^{'}$. Then the duality pairing is often written
$$langle f,vrangle_{X^{'},X} = f(v)$$



for $f in X^{'}$ and $v in X$. But is it allowed to write



$$
langle v,frangle_{X,X^{'}}
$$

to mean $langle f,vrangle_{X^{'},X}$?



In the setting of a Hilbert space $H$, for a given linear operator $A:Hto H^{'}$, I saw $A$ being self-adjont is written as



$$
langle Av,urangle = langle v,Aurangle
$$



Does $langle v,Aurangle$ here actually mean $langle Au,vrangle= Au(v)$?










share|cite|improve this question











$endgroup$












  • $begingroup$
    It's just a convention, there's no mathematics reason why you can only write $langle v,frangle$ but not $langle f,vrangle$ and vise versa. You just need to be consistence.
    $endgroup$
    – BigbearZzz
    Jan 17 at 19:03
















2












2








2





$begingroup$


Suppose we have a Banach space $X$ and its dual $X^{'}$. Then the duality pairing is often written
$$langle f,vrangle_{X^{'},X} = f(v)$$



for $f in X^{'}$ and $v in X$. But is it allowed to write



$$
langle v,frangle_{X,X^{'}}
$$

to mean $langle f,vrangle_{X^{'},X}$?



In the setting of a Hilbert space $H$, for a given linear operator $A:Hto H^{'}$, I saw $A$ being self-adjont is written as



$$
langle Av,urangle = langle v,Aurangle
$$



Does $langle v,Aurangle$ here actually mean $langle Au,vrangle= Au(v)$?










share|cite|improve this question











$endgroup$




Suppose we have a Banach space $X$ and its dual $X^{'}$. Then the duality pairing is often written
$$langle f,vrangle_{X^{'},X} = f(v)$$



for $f in X^{'}$ and $v in X$. But is it allowed to write



$$
langle v,frangle_{X,X^{'}}
$$

to mean $langle f,vrangle_{X^{'},X}$?



In the setting of a Hilbert space $H$, for a given linear operator $A:Hto H^{'}$, I saw $A$ being self-adjont is written as



$$
langle Av,urangle = langle v,Aurangle
$$



Does $langle v,Aurangle$ here actually mean $langle Au,vrangle= Au(v)$?







functional-analysis






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Jan 17 at 18:54









SvanN

2,0411422




2,0411422










asked Jan 17 at 18:51









mmnnmmnn

566




566












  • $begingroup$
    It's just a convention, there's no mathematics reason why you can only write $langle v,frangle$ but not $langle f,vrangle$ and vise versa. You just need to be consistence.
    $endgroup$
    – BigbearZzz
    Jan 17 at 19:03




















  • $begingroup$
    It's just a convention, there's no mathematics reason why you can only write $langle v,frangle$ but not $langle f,vrangle$ and vise versa. You just need to be consistence.
    $endgroup$
    – BigbearZzz
    Jan 17 at 19:03


















$begingroup$
It's just a convention, there's no mathematics reason why you can only write $langle v,frangle$ but not $langle f,vrangle$ and vise versa. You just need to be consistence.
$endgroup$
– BigbearZzz
Jan 17 at 19:03






$begingroup$
It's just a convention, there's no mathematics reason why you can only write $langle v,frangle$ but not $langle f,vrangle$ and vise versa. You just need to be consistence.
$endgroup$
– BigbearZzz
Jan 17 at 19:03












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