Motivation or intuition the identity $a=(b-(a-1)^{-1}b(a-1))(a^{-1}ba-(a-1)^{-1}b(a-1))^{-1}$, when $abneq...












3












$begingroup$


In proving the Cartan-Brauer-Hua theorem, Hua uses an obscure identity. That is:
$$
a=(b-(a-1)^{-1}b(a-1))(a^{-1}ba-(a-1)^{-1}b(a-1))^{-1}
$$

for $a$ and $b$ such that $ab neq ba$. All these elements belong to a division ring.
This identity confused me.I want to know some motivation or intuition about this
identity. Thanks for any help.










share|cite|improve this question











$endgroup$








  • 1




    $begingroup$
    Can you provide some more detail about what kind of objects $a$ and $b$ are? If everything commutes, this is not a well-defined statement. Otherwise it may be but it is still unclear which operations are permitted.
    $endgroup$
    – quarague
    Jan 28 at 10:33








  • 1




    $begingroup$
    Conjugation in a group is not "obscure".
    $endgroup$
    – Dietrich Burde
    Jan 28 at 10:48










  • $begingroup$
    I think whatever this identity is, it's probably equivalent to Hua's identity? If so, you're re-asking this question of mine, just with a different formulation of the identity.
    $endgroup$
    – rschwieb
    Jan 28 at 12:07










  • $begingroup$
    @rschwieb,does this identity could be implied by Hua's identity?
    $endgroup$
    – yuan
    Jan 28 at 12:13






  • 1




    $begingroup$
    I have added an answer to this question in math.stackexchange.com/questions/1602573/…
    $endgroup$
    – Jose Brox
    Jan 28 at 16:16
















3












$begingroup$


In proving the Cartan-Brauer-Hua theorem, Hua uses an obscure identity. That is:
$$
a=(b-(a-1)^{-1}b(a-1))(a^{-1}ba-(a-1)^{-1}b(a-1))^{-1}
$$

for $a$ and $b$ such that $ab neq ba$. All these elements belong to a division ring.
This identity confused me.I want to know some motivation or intuition about this
identity. Thanks for any help.










share|cite|improve this question











$endgroup$








  • 1




    $begingroup$
    Can you provide some more detail about what kind of objects $a$ and $b$ are? If everything commutes, this is not a well-defined statement. Otherwise it may be but it is still unclear which operations are permitted.
    $endgroup$
    – quarague
    Jan 28 at 10:33








  • 1




    $begingroup$
    Conjugation in a group is not "obscure".
    $endgroup$
    – Dietrich Burde
    Jan 28 at 10:48










  • $begingroup$
    I think whatever this identity is, it's probably equivalent to Hua's identity? If so, you're re-asking this question of mine, just with a different formulation of the identity.
    $endgroup$
    – rschwieb
    Jan 28 at 12:07










  • $begingroup$
    @rschwieb,does this identity could be implied by Hua's identity?
    $endgroup$
    – yuan
    Jan 28 at 12:13






  • 1




    $begingroup$
    I have added an answer to this question in math.stackexchange.com/questions/1602573/…
    $endgroup$
    – Jose Brox
    Jan 28 at 16:16














3












3








3


0



$begingroup$


In proving the Cartan-Brauer-Hua theorem, Hua uses an obscure identity. That is:
$$
a=(b-(a-1)^{-1}b(a-1))(a^{-1}ba-(a-1)^{-1}b(a-1))^{-1}
$$

for $a$ and $b$ such that $ab neq ba$. All these elements belong to a division ring.
This identity confused me.I want to know some motivation or intuition about this
identity. Thanks for any help.










share|cite|improve this question











$endgroup$




In proving the Cartan-Brauer-Hua theorem, Hua uses an obscure identity. That is:
$$
a=(b-(a-1)^{-1}b(a-1))(a^{-1}ba-(a-1)^{-1}b(a-1))^{-1}
$$

for $a$ and $b$ such that $ab neq ba$. All these elements belong to a division ring.
This identity confused me.I want to know some motivation or intuition about this
identity. Thanks for any help.







abstract-algebra ring-theory






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Jan 28 at 11:19







yuan

















asked Jan 28 at 9:47









yuanyuan

393




393








  • 1




    $begingroup$
    Can you provide some more detail about what kind of objects $a$ and $b$ are? If everything commutes, this is not a well-defined statement. Otherwise it may be but it is still unclear which operations are permitted.
    $endgroup$
    – quarague
    Jan 28 at 10:33








  • 1




    $begingroup$
    Conjugation in a group is not "obscure".
    $endgroup$
    – Dietrich Burde
    Jan 28 at 10:48










  • $begingroup$
    I think whatever this identity is, it's probably equivalent to Hua's identity? If so, you're re-asking this question of mine, just with a different formulation of the identity.
    $endgroup$
    – rschwieb
    Jan 28 at 12:07










  • $begingroup$
    @rschwieb,does this identity could be implied by Hua's identity?
    $endgroup$
    – yuan
    Jan 28 at 12:13






  • 1




    $begingroup$
    I have added an answer to this question in math.stackexchange.com/questions/1602573/…
    $endgroup$
    – Jose Brox
    Jan 28 at 16:16














  • 1




    $begingroup$
    Can you provide some more detail about what kind of objects $a$ and $b$ are? If everything commutes, this is not a well-defined statement. Otherwise it may be but it is still unclear which operations are permitted.
    $endgroup$
    – quarague
    Jan 28 at 10:33








  • 1




    $begingroup$
    Conjugation in a group is not "obscure".
    $endgroup$
    – Dietrich Burde
    Jan 28 at 10:48










  • $begingroup$
    I think whatever this identity is, it's probably equivalent to Hua's identity? If so, you're re-asking this question of mine, just with a different formulation of the identity.
    $endgroup$
    – rschwieb
    Jan 28 at 12:07










  • $begingroup$
    @rschwieb,does this identity could be implied by Hua's identity?
    $endgroup$
    – yuan
    Jan 28 at 12:13






  • 1




    $begingroup$
    I have added an answer to this question in math.stackexchange.com/questions/1602573/…
    $endgroup$
    – Jose Brox
    Jan 28 at 16:16








1




1




$begingroup$
Can you provide some more detail about what kind of objects $a$ and $b$ are? If everything commutes, this is not a well-defined statement. Otherwise it may be but it is still unclear which operations are permitted.
$endgroup$
– quarague
Jan 28 at 10:33






$begingroup$
Can you provide some more detail about what kind of objects $a$ and $b$ are? If everything commutes, this is not a well-defined statement. Otherwise it may be but it is still unclear which operations are permitted.
$endgroup$
– quarague
Jan 28 at 10:33






1




1




$begingroup$
Conjugation in a group is not "obscure".
$endgroup$
– Dietrich Burde
Jan 28 at 10:48




$begingroup$
Conjugation in a group is not "obscure".
$endgroup$
– Dietrich Burde
Jan 28 at 10:48












$begingroup$
I think whatever this identity is, it's probably equivalent to Hua's identity? If so, you're re-asking this question of mine, just with a different formulation of the identity.
$endgroup$
– rschwieb
Jan 28 at 12:07




$begingroup$
I think whatever this identity is, it's probably equivalent to Hua's identity? If so, you're re-asking this question of mine, just with a different formulation of the identity.
$endgroup$
– rschwieb
Jan 28 at 12:07












$begingroup$
@rschwieb,does this identity could be implied by Hua's identity?
$endgroup$
– yuan
Jan 28 at 12:13




$begingroup$
@rschwieb,does this identity could be implied by Hua's identity?
$endgroup$
– yuan
Jan 28 at 12:13




1




1




$begingroup$
I have added an answer to this question in math.stackexchange.com/questions/1602573/…
$endgroup$
– Jose Brox
Jan 28 at 16:16




$begingroup$
I have added an answer to this question in math.stackexchange.com/questions/1602573/…
$endgroup$
– Jose Brox
Jan 28 at 16:16










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