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代数幾何学セミナー
過去の記録 ～05/23｜次回の予定｜今後の予定 05/24～
| 開催情報 | 金曜日 13:30～15:00 数理科学研究科棟(駒場) 118号室 |
|---|---|
| 担当者 | 權業 善範、河上 龍郎 、榎園 誠 |
2013年01月15日(火)
15:30-17:00 数理科学研究科棟(駒場) 128号室
いつもと曜日・場所が異なります
Jungkai Alfred Chen 氏 (National Taiwan University)
Three Dimensional Birational Geoemtry--updates and problems (ENGLISH)
いつもと曜日・場所が異なります
Jungkai Alfred Chen 氏 (National Taiwan University)
Three Dimensional Birational Geoemtry--updates and problems (ENGLISH)
[ 講演概要 ]
In this talk I will talk about some recent results on
biratioanl classification and biratioanl geoemtry of threefolds.
Given a threefold of general type, we improved our previous result by
showing that $Vol \\ge 1/1680$ and $|mK_X|$ is biratioanl for $m \\ge
61$.
Compare with the worst known example that $X_{46} \\subset
\\mathbb{P}(4,5,6,7,23)$, one also knows that there are only finiteley
many singularities type
for threefolds of general type with $1/1680 \\le Vol \\le 1/420$. It is
then intereting to study threefolds of general type with given basket
of singularities and with given fiber structure.
Concerning threefolds with intermediate Kodaira dimension, we
considered the effective Iitaka fibration. For this purpose, it is
interesting to study threefolds with $\\kappa=1$ with given basket of
singularities and abelian fibration.
For explicit birational geoemtry, we will show our result that each
biratioanl map in minimal model program can be factored into a
sequence of following maps (or its inverse)
1. a divisorial contraction to a point of index r with discrepancy 1/r.
2. a blowup along a smooth curve
3. a flop
In this talk I will talk about some recent results on
biratioanl classification and biratioanl geoemtry of threefolds.
Given a threefold of general type, we improved our previous result by
showing that $Vol \\ge 1/1680$ and $|mK_X|$ is biratioanl for $m \\ge
61$.
Compare with the worst known example that $X_{46} \\subset
\\mathbb{P}(4,5,6,7,23)$, one also knows that there are only finiteley
many singularities type
for threefolds of general type with $1/1680 \\le Vol \\le 1/420$. It is
then intereting to study threefolds of general type with given basket
of singularities and with given fiber structure.
Concerning threefolds with intermediate Kodaira dimension, we
considered the effective Iitaka fibration. For this purpose, it is
interesting to study threefolds with $\\kappa=1$ with given basket of
singularities and abelian fibration.
For explicit birational geoemtry, we will show our result that each
biratioanl map in minimal model program can be factored into a
sequence of following maps (or its inverse)
1. a divisorial contraction to a point of index r with discrepancy 1/r.
2. a blowup along a smooth curve
3. a flop
