Riemann bilinear relations and meromorphic abelian differentials












1














I am getting quite confused with Riemann bilinear relations.



Let $Sigma$ be a compact Riemann surface of genus $g$, with a canonical homology basis $a_1,b_1,dots,a_g,b_g$, with associated normalised holomorphic and anti-holomorphic one-forms $omega_I,bar omega_I$, $I=1dots,g$, such that $oint_{a_I} omega_J = delta_{IJ}$.



Let further $tau_{P,Q}$ be an abelian differential on $Sigma$ with poles at $P,Q$ of residues $pm1$, normalised so that its $a$-cycles periods are zero : $$oint_{a_I} tau_{PQ}=0.$$
It is called an abelian differential of the third kind and the normalisation guarantees that it is unique. Besides, it is closed on $Sigma-{P,Q}$.
For more details, see Bobenko or textbooks on Riemann surfaces like Farkas & Kra.



I've read in a few places the following statement:
$$iint_Sigma tau_{PQ} wedge bar omega_J propto int_Q^P Im omega_J$$
up to some factors of $2,pi,i$ and sign.



I can't get where the imaginary part comes from. Calling $f=overline{int^zomega_J}$, it seems to me that the standard proof of the Riemann identities based on Stokes theorem, $int_{partial Sigma} f tau_{PQ} = iint bar omega_J wedge tau_{PQ}$ will hold ($partial Sigma$ means the union of $a,b,a^{-1}$ and $b^{-1}$ cycles that constitute a canonical dissection of the surface; the standard 4g-gon) and because $tau_{PQ}$ has zero a-periods this is evaluated to
$$iint_Sigma tau_{PQ} wedge bar omega_J = sum_{I=1}^g oint_{a_I} bar omega_J oint_{b_I} omega_{P,Q}, $$which, using some reciprocity formula like $oint_{b_i} omega_{P,Q} = 2ipi int_Q^P omega_i $ will yield
$$iint_Sigma tau_{PQ} wedge bar omega_J = 2ipi int_Q^P omega_J$$ without the imaginary part ?










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  • 1




    It's too hard to figure out what's going on from what little you've put here. For example, what are the $1$-forms $omega_{P,Q}$? Do you have a link to a complete text?
    – Ted Shifrin
    Jan 5 at 0:31










  • I've updated a bit the text... Don't know if this helps.
    – picop
    Jan 5 at 8:35
















1














I am getting quite confused with Riemann bilinear relations.



Let $Sigma$ be a compact Riemann surface of genus $g$, with a canonical homology basis $a_1,b_1,dots,a_g,b_g$, with associated normalised holomorphic and anti-holomorphic one-forms $omega_I,bar omega_I$, $I=1dots,g$, such that $oint_{a_I} omega_J = delta_{IJ}$.



Let further $tau_{P,Q}$ be an abelian differential on $Sigma$ with poles at $P,Q$ of residues $pm1$, normalised so that its $a$-cycles periods are zero : $$oint_{a_I} tau_{PQ}=0.$$
It is called an abelian differential of the third kind and the normalisation guarantees that it is unique. Besides, it is closed on $Sigma-{P,Q}$.
For more details, see Bobenko or textbooks on Riemann surfaces like Farkas & Kra.



I've read in a few places the following statement:
$$iint_Sigma tau_{PQ} wedge bar omega_J propto int_Q^P Im omega_J$$
up to some factors of $2,pi,i$ and sign.



I can't get where the imaginary part comes from. Calling $f=overline{int^zomega_J}$, it seems to me that the standard proof of the Riemann identities based on Stokes theorem, $int_{partial Sigma} f tau_{PQ} = iint bar omega_J wedge tau_{PQ}$ will hold ($partial Sigma$ means the union of $a,b,a^{-1}$ and $b^{-1}$ cycles that constitute a canonical dissection of the surface; the standard 4g-gon) and because $tau_{PQ}$ has zero a-periods this is evaluated to
$$iint_Sigma tau_{PQ} wedge bar omega_J = sum_{I=1}^g oint_{a_I} bar omega_J oint_{b_I} omega_{P,Q}, $$which, using some reciprocity formula like $oint_{b_i} omega_{P,Q} = 2ipi int_Q^P omega_i $ will yield
$$iint_Sigma tau_{PQ} wedge bar omega_J = 2ipi int_Q^P omega_J$$ without the imaginary part ?










share|cite|improve this question




















  • 1




    It's too hard to figure out what's going on from what little you've put here. For example, what are the $1$-forms $omega_{P,Q}$? Do you have a link to a complete text?
    – Ted Shifrin
    Jan 5 at 0:31










  • I've updated a bit the text... Don't know if this helps.
    – picop
    Jan 5 at 8:35














1












1








1







I am getting quite confused with Riemann bilinear relations.



Let $Sigma$ be a compact Riemann surface of genus $g$, with a canonical homology basis $a_1,b_1,dots,a_g,b_g$, with associated normalised holomorphic and anti-holomorphic one-forms $omega_I,bar omega_I$, $I=1dots,g$, such that $oint_{a_I} omega_J = delta_{IJ}$.



Let further $tau_{P,Q}$ be an abelian differential on $Sigma$ with poles at $P,Q$ of residues $pm1$, normalised so that its $a$-cycles periods are zero : $$oint_{a_I} tau_{PQ}=0.$$
It is called an abelian differential of the third kind and the normalisation guarantees that it is unique. Besides, it is closed on $Sigma-{P,Q}$.
For more details, see Bobenko or textbooks on Riemann surfaces like Farkas & Kra.



I've read in a few places the following statement:
$$iint_Sigma tau_{PQ} wedge bar omega_J propto int_Q^P Im omega_J$$
up to some factors of $2,pi,i$ and sign.



I can't get where the imaginary part comes from. Calling $f=overline{int^zomega_J}$, it seems to me that the standard proof of the Riemann identities based on Stokes theorem, $int_{partial Sigma} f tau_{PQ} = iint bar omega_J wedge tau_{PQ}$ will hold ($partial Sigma$ means the union of $a,b,a^{-1}$ and $b^{-1}$ cycles that constitute a canonical dissection of the surface; the standard 4g-gon) and because $tau_{PQ}$ has zero a-periods this is evaluated to
$$iint_Sigma tau_{PQ} wedge bar omega_J = sum_{I=1}^g oint_{a_I} bar omega_J oint_{b_I} omega_{P,Q}, $$which, using some reciprocity formula like $oint_{b_i} omega_{P,Q} = 2ipi int_Q^P omega_i $ will yield
$$iint_Sigma tau_{PQ} wedge bar omega_J = 2ipi int_Q^P omega_J$$ without the imaginary part ?










share|cite|improve this question















I am getting quite confused with Riemann bilinear relations.



Let $Sigma$ be a compact Riemann surface of genus $g$, with a canonical homology basis $a_1,b_1,dots,a_g,b_g$, with associated normalised holomorphic and anti-holomorphic one-forms $omega_I,bar omega_I$, $I=1dots,g$, such that $oint_{a_I} omega_J = delta_{IJ}$.



Let further $tau_{P,Q}$ be an abelian differential on $Sigma$ with poles at $P,Q$ of residues $pm1$, normalised so that its $a$-cycles periods are zero : $$oint_{a_I} tau_{PQ}=0.$$
It is called an abelian differential of the third kind and the normalisation guarantees that it is unique. Besides, it is closed on $Sigma-{P,Q}$.
For more details, see Bobenko or textbooks on Riemann surfaces like Farkas & Kra.



I've read in a few places the following statement:
$$iint_Sigma tau_{PQ} wedge bar omega_J propto int_Q^P Im omega_J$$
up to some factors of $2,pi,i$ and sign.



I can't get where the imaginary part comes from. Calling $f=overline{int^zomega_J}$, it seems to me that the standard proof of the Riemann identities based on Stokes theorem, $int_{partial Sigma} f tau_{PQ} = iint bar omega_J wedge tau_{PQ}$ will hold ($partial Sigma$ means the union of $a,b,a^{-1}$ and $b^{-1}$ cycles that constitute a canonical dissection of the surface; the standard 4g-gon) and because $tau_{PQ}$ has zero a-periods this is evaluated to
$$iint_Sigma tau_{PQ} wedge bar omega_J = sum_{I=1}^g oint_{a_I} bar omega_J oint_{b_I} omega_{P,Q}, $$which, using some reciprocity formula like $oint_{b_i} omega_{P,Q} = 2ipi int_Q^P omega_i $ will yield
$$iint_Sigma tau_{PQ} wedge bar omega_J = 2ipi int_Q^P omega_J$$ without the imaginary part ?







differential-forms complex-integration riemann-surfaces






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edited Jan 6 at 10:20







picop

















asked Jan 4 at 20:59









picoppicop

507




507








  • 1




    It's too hard to figure out what's going on from what little you've put here. For example, what are the $1$-forms $omega_{P,Q}$? Do you have a link to a complete text?
    – Ted Shifrin
    Jan 5 at 0:31










  • I've updated a bit the text... Don't know if this helps.
    – picop
    Jan 5 at 8:35














  • 1




    It's too hard to figure out what's going on from what little you've put here. For example, what are the $1$-forms $omega_{P,Q}$? Do you have a link to a complete text?
    – Ted Shifrin
    Jan 5 at 0:31










  • I've updated a bit the text... Don't know if this helps.
    – picop
    Jan 5 at 8:35








1




1




It's too hard to figure out what's going on from what little you've put here. For example, what are the $1$-forms $omega_{P,Q}$? Do you have a link to a complete text?
– Ted Shifrin
Jan 5 at 0:31




It's too hard to figure out what's going on from what little you've put here. For example, what are the $1$-forms $omega_{P,Q}$? Do you have a link to a complete text?
– Ted Shifrin
Jan 5 at 0:31












I've updated a bit the text... Don't know if this helps.
– picop
Jan 5 at 8:35




I've updated a bit the text... Don't know if this helps.
– picop
Jan 5 at 8:35










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