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							| @@ -27,3 +27,6 @@ Albanese | ||||
| Hirzebruch | ||||
| multiplicitity | ||||
| subvariety | ||||
| Cremona | ||||
| equivariant | ||||
| bimeromorphic | ||||
|   | ||||
| @@ -36,7 +36,7 @@ | ||||
| \todo{define torus quotient} | ||||
|  | ||||
|  | ||||
| \begin{defn}[The $\cC$-Albanese of a compact pair with trivial boundary]\label{def:1-2}% | ||||
| \begin{defn}[\protect{The Albanese of a compact pair with trivial boundary, \cite[Def.~9.1]{orbiAlb2}}]\label{def:1-2}% | ||||
|   Let $X$ be a compact Kähler manifold.  An Albanese of the $\cC$-pair $(X,0)$ | ||||
|   is a torus quotient $(A, Δ_A)$ and a $\cC$-morphism | ||||
|   \[ | ||||
| @@ -61,9 +61,9 @@ | ||||
|   \] | ||||
| \end{rem} | ||||
|  | ||||
| \begin{thm}[The Albanese of a $\cC$-pair]\label{thm:22-1} % | ||||
| \begin{thm}[\protect{Existence of the Albanese, \cite[Thm.~9.2]{orbiAlb2}}]\label{thm:22-1} % | ||||
|   Let $X$ be a compact Kähler manifold.  If $q^+_{\Alb}(X,0) < ∞$, then an | ||||
|   Albanese of $(X,0)$ exists. | ||||
|   Albanese of $(X,0)$ exists.  \qed | ||||
| \end{thm} | ||||
|  | ||||
|  | ||||
|   | ||||
| @@ -26,12 +26,9 @@ | ||||
|       \bP¹ \ar[r, "n\text{, normalization}"'] \ar[rr, bend left=15, "\eta"] & C  \ar[r, "\text{inclusion}"'] & X. | ||||
|     \end{tikzcd} | ||||
|   \] | ||||
|   Consider the points $0 \in \bP¹$ and $x' := n(0) \in X$.   | ||||
|    | ||||
|   Given that $X$ is smooth, recall from \cite{orbiAlb1} that $\eta$ is a | ||||
|   $\cC$-morphism, between $\cC$-pairs $(\bP¹, 0)$ and $(X, 0)$. Since | ||||
|   $\Alb(\bP¹,0)$ exists, the universal property of the Albanese yields a | ||||
|   diagram | ||||
|   Given that $X$ is smooth, recall from \cite[Ex.~8.6]{orbiAlb1} that $\eta$ is | ||||
|   a $\cC$-morphism, between $\cC$-pairs $(\bP¹, 0)$ and $(X, 0)$. Since | ||||
|   $\Alb(\bP¹,0)$ exists, the universal property of the Albanese yields a diagram | ||||
|   \[ | ||||
|     \begin{tikzcd}[column sep=2cm] | ||||
|       \bP¹ \ar[r, "\alb(\bP¹{,}0)"] \ar[d, "n"'] & \Alb(\bP¹,0) \ar[d] \\ | ||||
| @@ -41,15 +38,18 @@ | ||||
|   The claim follows immediately once we observe that $\Alb(\bP¹,0)$ is a point. | ||||
| \end{proof} | ||||
|  | ||||
| \todo{There is nothing special about $\bP¹$ here. This works for every space with nontrivial $\cC$-Albanese.} | ||||
|  | ||||
| \begin{cor}\label{cor:2}% | ||||
|   In Setting~\ref{set:1}, let $\mu : X \to Y$ be a morphism to a normal | ||||
|   projective variety.  If all fibres of $\mu$ are rationally chain connected, | ||||
|   then $\alb(X,0)$ factors via $\mu$, | ||||
|   In Setting~\ref{set:1}, let $\mu : X \to Y$ be a morphism to a normal analytic | ||||
|   variety.  If all fibres of $\mu$ are rationally chain connected, then | ||||
|   $\alb(X,0)$ factors via $\mu$, | ||||
|   \[ | ||||
|     \begin{tikzcd} | ||||
|       X \ar[r, "\mu"'] \ar[rr, bend left=15, "\alb(X{,}0)"] & Y \ar[r, "\exists!\:\beta"'] & \Alb(X,0). | ||||
|     \end{tikzcd} | ||||
|   \] | ||||
|   \qed   | ||||
| \end{cor} | ||||
|  | ||||
| \begin{cor}\label{cor:3}% | ||||
| @@ -57,13 +57,52 @@ | ||||
|   $\Alb(X,0)$ is a point. | ||||
| \end{cor} | ||||
|  | ||||
|  | ||||
| \begin{cor}\label{cor:4}% | ||||
|   In Setting~\ref{set:1}, let $\mu : X \to Y$ be a bimeromorphic modification of | ||||
|   a compact manifold $Y$.  Then, $\alb(X,0)$ factors via $\mu$, | ||||
|   \[ | ||||
|     \begin{tikzcd} | ||||
|       X \ar[r, "\mu"'] \ar[rr, bend left=15, "\alb(X{,}0)"] & Y \ar[r, "\exists!\:\beta"'] & \Alb(X,0), | ||||
|     \end{tikzcd} | ||||
|   \] | ||||
|   the morphism $\beta$ is a $\cC$-morphism between the pairs $(Y,0)$ and | ||||
|   $\Alb(X,0)$, and $\beta : (Y,0) \to \Alb(Y,0)$ is an Albanese of $(Y,0)$. | ||||
| \end{cor} | ||||
| \begin{proof} | ||||
|   \todo{PENDING} | ||||
| \end{proof} | ||||
|  | ||||
| \begin{cor}\label{cor:5}% | ||||
|   In Setting~\ref{set:1}, let $Y$ be a compact Kähler manifold bimeromorphic to | ||||
|   $X$. Then, an Albanese of $(Y,0)$ exists.  If $f : X \dasharrow Y$ is | ||||
|   bimeromorphic, then there exists a unique morphism of $\cC$-pairs rendering | ||||
|   the following diagram commutative, | ||||
|   \[ | ||||
|     \begin{tikzcd} | ||||
|       X \ar[d, "\alb(X{,}0)"'] \ar[r, dashed, "f"] & Y \ar[d, "\alb(Y{,}0)"'] \\ | ||||
|       \Alb(X,0) \ar[r, "\exists! \alb(f)"'] & \Alb(Y,0) | ||||
|     \end{tikzcd} | ||||
|   \] | ||||
| \end{cor} | ||||
| \begin{proof} | ||||
|   \todo{PENDING} | ||||
| \end{proof} | ||||
|  | ||||
| \begin{cor}\label{cor:6}% | ||||
|   In Setting~\ref{set:1}, the automorphism group of $X$ and the Cremona group | ||||
|   act on $\Alb(X,0)$ in a way that makes the morphism $\alb(X,0)$ equivariant. | ||||
| \end{cor} | ||||
| \begin{proof} | ||||
|   \todo{PENDING} | ||||
| \end{proof} | ||||
|  | ||||
| \todo{ | ||||
|   \begin{itemize} | ||||
|     \item Need example where a rational variety has a  | ||||
|     \item Factorization via minimal model. | ||||
|     \item Independence of bimeromorphic model. | ||||
|     \item Factorization via MRC quotient. | ||||
|     \item For varieties of general type, factorization via the canonical. | ||||
|   \end{itemize} | ||||
|  | ||||
| } | ||||
|  | ||||
| \begin{example}[Theorem~\ref{thm:1} is wrong for singular spaces] | ||||
|   | ||||
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