Some questions about Clemens' paper Cohomology and Obstructions I: Geometry of formal Kuranishi theory

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I am reading the paper Cohomology and Obstructions I: Geometry of formal Kuranishi theory written by Herbert Clemens. I have found this paper hard to follow even though I am familiar with the classical deformaion theory developed by Kodaira-Spencer. In particular, I have the following questions:



  1. In the last paragraph of page 11, Clemens write, If for an ideal $mathfrakAsubseteq mathfrakm=t_1,cdots,t_s$, we let
    $$Delta_mathfrakA:= SpecfracmathbbC[t]mathfrakAsubseteq Delta.$$
    I should add that $Delta$ is a polydisc with coordinates $t_1,cdots,t_s$. My question is that what is the meaning of the inclusion $SpecfracmathbbC[t]mathfrakAsubseteq Delta$? Is this inclusion in the category of schemes or complex sapces? I have the same question for
    $$M_mathfrakA:=pi^-1(Delta_mathfrakA),$$
    where $pi: Mto Delta$ is a deformation of the central fiber $M_0$.


  2. In page 18. What is the meaning of the sentence "$M_mathfrakA/Delta_mathfrakA$is an infinitesimal deformation of compact Kahler manifolds"? What is the definition of extending a family $M_mathfrakA/Delta_mathfrakA$ to a family $M_mathfrakA'/Delta_mathfrakA'$ for some ideal $mathfrakAsupseteq mathfrakA'supseteq mathfrakmmathfrakA$.?










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    I am reading the paper Cohomology and Obstructions I: Geometry of formal Kuranishi theory written by Herbert Clemens. I have found this paper hard to follow even though I am familiar with the classical deformaion theory developed by Kodaira-Spencer. In particular, I have the following questions:



    1. In the last paragraph of page 11, Clemens write, If for an ideal $mathfrakAsubseteq mathfrakm=t_1,cdots,t_s$, we let
      $$Delta_mathfrakA:= SpecfracmathbbC[t]mathfrakAsubseteq Delta.$$
      I should add that $Delta$ is a polydisc with coordinates $t_1,cdots,t_s$. My question is that what is the meaning of the inclusion $SpecfracmathbbC[t]mathfrakAsubseteq Delta$? Is this inclusion in the category of schemes or complex sapces? I have the same question for
      $$M_mathfrakA:=pi^-1(Delta_mathfrakA),$$
      where $pi: Mto Delta$ is a deformation of the central fiber $M_0$.


    2. In page 18. What is the meaning of the sentence "$M_mathfrakA/Delta_mathfrakA$is an infinitesimal deformation of compact Kahler manifolds"? What is the definition of extending a family $M_mathfrakA/Delta_mathfrakA$ to a family $M_mathfrakA'/Delta_mathfrakA'$ for some ideal $mathfrakAsupseteq mathfrakA'supseteq mathfrakmmathfrakA$.?










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      up vote
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      up vote
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      down vote

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      I am reading the paper Cohomology and Obstructions I: Geometry of formal Kuranishi theory written by Herbert Clemens. I have found this paper hard to follow even though I am familiar with the classical deformaion theory developed by Kodaira-Spencer. In particular, I have the following questions:



      1. In the last paragraph of page 11, Clemens write, If for an ideal $mathfrakAsubseteq mathfrakm=t_1,cdots,t_s$, we let
        $$Delta_mathfrakA:= SpecfracmathbbC[t]mathfrakAsubseteq Delta.$$
        I should add that $Delta$ is a polydisc with coordinates $t_1,cdots,t_s$. My question is that what is the meaning of the inclusion $SpecfracmathbbC[t]mathfrakAsubseteq Delta$? Is this inclusion in the category of schemes or complex sapces? I have the same question for
        $$M_mathfrakA:=pi^-1(Delta_mathfrakA),$$
        where $pi: Mto Delta$ is a deformation of the central fiber $M_0$.


      2. In page 18. What is the meaning of the sentence "$M_mathfrakA/Delta_mathfrakA$is an infinitesimal deformation of compact Kahler manifolds"? What is the definition of extending a family $M_mathfrakA/Delta_mathfrakA$ to a family $M_mathfrakA'/Delta_mathfrakA'$ for some ideal $mathfrakAsupseteq mathfrakA'supseteq mathfrakmmathfrakA$.?










      share|cite|improve this question













      I am reading the paper Cohomology and Obstructions I: Geometry of formal Kuranishi theory written by Herbert Clemens. I have found this paper hard to follow even though I am familiar with the classical deformaion theory developed by Kodaira-Spencer. In particular, I have the following questions:



      1. In the last paragraph of page 11, Clemens write, If for an ideal $mathfrakAsubseteq mathfrakm=t_1,cdots,t_s$, we let
        $$Delta_mathfrakA:= SpecfracmathbbC[t]mathfrakAsubseteq Delta.$$
        I should add that $Delta$ is a polydisc with coordinates $t_1,cdots,t_s$. My question is that what is the meaning of the inclusion $SpecfracmathbbC[t]mathfrakAsubseteq Delta$? Is this inclusion in the category of schemes or complex sapces? I have the same question for
        $$M_mathfrakA:=pi^-1(Delta_mathfrakA),$$
        where $pi: Mto Delta$ is a deformation of the central fiber $M_0$.


      2. In page 18. What is the meaning of the sentence "$M_mathfrakA/Delta_mathfrakA$is an infinitesimal deformation of compact Kahler manifolds"? What is the definition of extending a family $M_mathfrakA/Delta_mathfrakA$ to a family $M_mathfrakA'/Delta_mathfrakA'$ for some ideal $mathfrakAsupseteq mathfrakA'supseteq mathfrakmmathfrakA$.?







      ag.algebraic-geometry complex-geometry deformation-theory






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      Wei Xia

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          1. It is an inclusion of analytic spaces — $Delta $ is not a scheme. If $mathfrakA=(f_1,ldots ,f_p)$, $Delta _mathfrakA$ is the subspace of $Delta $ defined by $f_1=ldots =f_p=0$. I think $mathfrakAneq 0$ is implicitely assumed, so $Delta _mathfrakA$ is a fattening of the origin. Hence $M _mathfrakA$ is what is called an infinitesimal deformation of $M_0$.


          2. If $mathfrakA'subset mathfrakA$, $Delta _mathfrakA$ is a subspace of $Delta _mathfrakA'$, so you look for a family over $Delta _mathfrakA'$ which induces the given family over $Delta _mathfrakA$.


          I think your questions would be more appropriate on MSE.






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            1. It is an inclusion of analytic spaces — $Delta $ is not a scheme. If $mathfrakA=(f_1,ldots ,f_p)$, $Delta _mathfrakA$ is the subspace of $Delta $ defined by $f_1=ldots =f_p=0$. I think $mathfrakAneq 0$ is implicitely assumed, so $Delta _mathfrakA$ is a fattening of the origin. Hence $M _mathfrakA$ is what is called an infinitesimal deformation of $M_0$.


            2. If $mathfrakA'subset mathfrakA$, $Delta _mathfrakA$ is a subspace of $Delta _mathfrakA'$, so you look for a family over $Delta _mathfrakA'$ which induces the given family over $Delta _mathfrakA$.


            I think your questions would be more appropriate on MSE.






            share|cite|improve this answer
























              up vote
              3
              down vote













              1. It is an inclusion of analytic spaces — $Delta $ is not a scheme. If $mathfrakA=(f_1,ldots ,f_p)$, $Delta _mathfrakA$ is the subspace of $Delta $ defined by $f_1=ldots =f_p=0$. I think $mathfrakAneq 0$ is implicitely assumed, so $Delta _mathfrakA$ is a fattening of the origin. Hence $M _mathfrakA$ is what is called an infinitesimal deformation of $M_0$.


              2. If $mathfrakA'subset mathfrakA$, $Delta _mathfrakA$ is a subspace of $Delta _mathfrakA'$, so you look for a family over $Delta _mathfrakA'$ which induces the given family over $Delta _mathfrakA$.


              I think your questions would be more appropriate on MSE.






              share|cite|improve this answer






















                up vote
                3
                down vote










                up vote
                3
                down vote









                1. It is an inclusion of analytic spaces — $Delta $ is not a scheme. If $mathfrakA=(f_1,ldots ,f_p)$, $Delta _mathfrakA$ is the subspace of $Delta $ defined by $f_1=ldots =f_p=0$. I think $mathfrakAneq 0$ is implicitely assumed, so $Delta _mathfrakA$ is a fattening of the origin. Hence $M _mathfrakA$ is what is called an infinitesimal deformation of $M_0$.


                2. If $mathfrakA'subset mathfrakA$, $Delta _mathfrakA$ is a subspace of $Delta _mathfrakA'$, so you look for a family over $Delta _mathfrakA'$ which induces the given family over $Delta _mathfrakA$.


                I think your questions would be more appropriate on MSE.






                share|cite|improve this answer












                1. It is an inclusion of analytic spaces — $Delta $ is not a scheme. If $mathfrakA=(f_1,ldots ,f_p)$, $Delta _mathfrakA$ is the subspace of $Delta $ defined by $f_1=ldots =f_p=0$. I think $mathfrakAneq 0$ is implicitely assumed, so $Delta _mathfrakA$ is a fattening of the origin. Hence $M _mathfrakA$ is what is called an infinitesimal deformation of $M_0$.


                2. If $mathfrakA'subset mathfrakA$, $Delta _mathfrakA$ is a subspace of $Delta _mathfrakA'$, so you look for a family over $Delta _mathfrakA'$ which induces the given family over $Delta _mathfrakA$.


                I think your questions would be more appropriate on MSE.







                share|cite|improve this answer












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                answered 4 hours ago









                abx

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