We study the blowing-up X of a smooth projective variety X along a smooth center B that is equipped with a projective bundle structure over a variety Z.If the Picard number p(X)is 1 and dim X is at most 4,we classify ...We study the blowing-up X of a smooth projective variety X along a smooth center B that is equipped with a projective bundle structure over a variety Z.If the Picard number p(X)is 1 and dim X is at most 4,we classify all such pairs(X,B).If X is a projective space P_(n)(n≥5)and dim B is 2,we show that B is a linear subspace in X.展开更多
The history of Finsler geometry is reviewed and briefly recent development in Finsler geometry and its application is completed systematically.Furthermore,an interesting open problem has been proposed in this field.
Consider a compact symplectic sub-orbifold groupoid S of a compact symplectic orbifold groupoid(X,ω).LetXabe the weight-a blowup of X along S,and Da=PNa be the exceptional divisor,where N is the normal bundle of S in...Consider a compact symplectic sub-orbifold groupoid S of a compact symplectic orbifold groupoid(X,ω).LetXabe the weight-a blowup of X along S,and Da=PNa be the exceptional divisor,where N is the normal bundle of S in X.In this paper we show that the absolute orbifold Gromov-Witten theory ofXacan be effectively and uniquely reconstructed from the absolute orbifold Gromov-Witten theories of X,S and Da,the natural restriction homomorphism HCR^*(X)→HCR*(S)and the first Chern class of the tautological line bundle over DQ.To achieve this we first prove similar results for the relative orbifold Gromov-Witten theories of(Xa|Da)and(Na|Da).As applications of these results,we prove an orbifold version of a conjecture of Maulik and Pandharipande(Topology,2006)on the Gromov-Witten theory of blowups along complete intersections,a conjecture on the Gromov-Witten theory of root constructions and a conjecture on the Leray-Hirsch result for the orbifold Gromov-Witten theory of Tseng and You(J Pure Appl Algebra,2016).展开更多
Special generators of the unoriented cobordism ring MO* are constructed to determine the groups J<sub>n,k</sub><sup>τ</sup> of n-dimensional cobordism classes in MO<sub>n</sub> con...Special generators of the unoriented cobordism ring MO* are constructed to determine the groups J<sub>n,k</sub><sup>τ</sup> of n-dimensional cobordism classes in MO<sub>n</sub> containing a representative M<sup>n</sup> admitting a （Z<sub>2</sub>）<sup>k</sup> -action with fixed point set of constant codimension.展开更多
The non-abelian Hodge correspondence was established by Corlette(1988),Donaldson(1987),Hit chin(1987)and Simpson(1988,1992).It states that on a compact Kahler manifold(X,ω),there is a one-to-one correspondence betwee...The non-abelian Hodge correspondence was established by Corlette(1988),Donaldson(1987),Hit chin(1987)and Simpson(1988,1992).It states that on a compact Kahler manifold(X,ω),there is a one-to-one correspondence between the moduli space of semi-simple flat complex vector bundles and the moduli space of poly-stable Higgs bundles with vanishing Chern numbers.In this paper,we extend this correspondence to the projectively flat bundles over some non-Kahler manifold cases.Firstly,we prove an existence theorem of Poisson metrics on simple projectively flat bundles over compact Hermitian manifolds.As its application,we obtain a vanishing theorem of characteristic classes of projectively flat bundles.Secondly,on compact Hermitian manifolds which satisfy Gauduchon and astheno-K?hler conditions,we combine the continuity method and the heat flow method to prove that every semi-stable Higgs bundle withΔ(E,?E)·[ωn-2]=0 must be an extension of stable Higgs bundles.Using the above results,over some compact non-Kahler manifolds(M,ω),we establish an equivalence of categories between the category of semi-stable(poly-stable)Higgs bundles(E,?E,φ)withΔ(E,?E)·[ωn-2]=0 and the category of(semi-simple)projectively flat bundles(E,D)with(-1)(1/2)FD=α■IdE for some real(1,1)-formα.展开更多
Special generators of the unoriented cobordism ring MO<sub>*</sub> are constructed to determine some groups J<sub>n,k</sub><sup>l<sub>1</sub>,l<sub>2</sub>,…,l<...Special generators of the unoriented cobordism ring MO<sub>*</sub> are constructed to determine some groups J<sub>n,k</sub><sup>l<sub>1</sub>,l<sub>2</sub>,…,l<sub>m</sub></sup> of cobordism classes in MO<sub>n</sub> containing a representative M<sup>n</sup> admitting a （Z<sub>2</sub>）<sup>k</sup>-action with the fixed point set of（n-l<sub>i</sub>）-dimensional submanifolds of M<sup>n</sup>.展开更多
基金supported by National Natural Science Foundation of China(12001547)Guangdong Basic and Applied Basic Research Foundation(2019A1515110907).
文摘We study the blowing-up X of a smooth projective variety X along a smooth center B that is equipped with a projective bundle structure over a variety Z.If the Picard number p(X)is 1 and dim X is at most 4,we classify all such pairs(X,B).If X is a projective space P_(n)(n≥5)and dim B is 2,we show that B is a linear subspace in X.
基金supported by Wang KC Foundation of Hong Kongthe National Natural Science Foundation of China.
文摘The history of Finsler geometry is reviewed and briefly recent development in Finsler geometry and its application is completed systematically.Furthermore,an interesting open problem has been proposed in this field.
基金supported by National Natural Science Foundation of China(Grant Nos.11890663,11821001,11826102 and 11501393)the Sichuan Science and Technology Program(Grant No.2019YJ0509)a joint research project of Laurent Mathematics Research Center of Sichuan Normal University and V.C.&V.R.Key Lab of Sichuan Province。
文摘Consider a compact symplectic sub-orbifold groupoid S of a compact symplectic orbifold groupoid(X,ω).LetXabe the weight-a blowup of X along S,and Da=PNa be the exceptional divisor,where N is the normal bundle of S in X.In this paper we show that the absolute orbifold Gromov-Witten theory ofXacan be effectively and uniquely reconstructed from the absolute orbifold Gromov-Witten theories of X,S and Da,the natural restriction homomorphism HCR^*(X)→HCR*(S)and the first Chern class of the tautological line bundle over DQ.To achieve this we first prove similar results for the relative orbifold Gromov-Witten theories of(Xa|Da)and(Na|Da).As applications of these results,we prove an orbifold version of a conjecture of Maulik and Pandharipande(Topology,2006)on the Gromov-Witten theory of blowups along complete intersections,a conjecture on the Gromov-Witten theory of root constructions and a conjecture on the Leray-Hirsch result for the orbifold Gromov-Witten theory of Tseng and You(J Pure Appl Algebra,2016).
文摘Special generators of the unoriented cobordism ring MO* are constructed to determine the groups J<sub>n,k</sub><sup>τ</sup> of n-dimensional cobordism classes in MO<sub>n</sub> containing a representative M<sup>n</sup> admitting a （Z<sub>2</sub>）<sup>k</sup> -action with fixed point set of constant codimension.
基金supported by the National Key R&D Program of China(Grant No.2020YFA0713100)National Natural Science Foundation of China(Grant Nos.12141104,11801535,11721101and 11625106)。
文摘The non-abelian Hodge correspondence was established by Corlette(1988),Donaldson(1987),Hit chin(1987)and Simpson(1988,1992).It states that on a compact Kahler manifold(X,ω),there is a one-to-one correspondence between the moduli space of semi-simple flat complex vector bundles and the moduli space of poly-stable Higgs bundles with vanishing Chern numbers.In this paper,we extend this correspondence to the projectively flat bundles over some non-Kahler manifold cases.Firstly,we prove an existence theorem of Poisson metrics on simple projectively flat bundles over compact Hermitian manifolds.As its application,we obtain a vanishing theorem of characteristic classes of projectively flat bundles.Secondly,on compact Hermitian manifolds which satisfy Gauduchon and astheno-K?hler conditions,we combine the continuity method and the heat flow method to prove that every semi-stable Higgs bundle withΔ(E,?E)·[ωn-2]=0 must be an extension of stable Higgs bundles.Using the above results,over some compact non-Kahler manifolds(M,ω),we establish an equivalence of categories between the category of semi-stable(poly-stable)Higgs bundles(E,?E,φ)withΔ(E,?E)·[ωn-2]=0 and the category of(semi-simple)projectively flat bundles(E,D)with(-1)(1/2)FD=α■IdE for some real(1,1)-formα.
文摘Special generators of the unoriented cobordism ring MO<sub>*</sub> are constructed to determine some groups J<sub>n,k</sub><sup>l<sub>1</sub>,l<sub>2</sub>,…,l<sub>m</sub></sup> of cobordism classes in MO<sub>n</sub> containing a representative M<sup>n</sup> admitting a （Z<sub>2</sub>）<sup>k</sup>-action with the fixed point set of（n-l<sub>i</sub>）-dimensional submanifolds of M<sup>n</sup>.
