scholarly journals Triple covers and a non-simply connected surface spanning an elongated tetrahedron and beating the cone

2018 ◽  
Vol 20 (3) ◽  
pp. 407-436 ◽  
Author(s):  
Giovanni Bellettini ◽  
Maurizio Paolini ◽  
Franco Pasquarelli
2009 ◽  
Vol 13 (3) ◽  
pp. 1483-1494 ◽  
Author(s):  
Heesang Park ◽  
Jongil Park ◽  
Dongsoo Shin

Author(s):  
S. Nag ◽  
J. A. Hillman ◽  
B. Datta

AbstractWe have defined and studied some pseudogroups of local diffeomorphisms which generalise the complex analytic pseudogroups. A 4-dimensional (or 8-dimensional) manifold modelled on these ‘Further pseudogroups’ turns out to be a quaternionic (respectively octonionic) manifold.We characterise compact Further manifolds as being products of compact Riemann surfaces with appropriate dimensional spheres. It then transpires that a connected compact quaternionic (H) (respectively O) manifold X, minus a finite number of circles (its ‘real set’), is the orientation double covering of the product Y × P2, (respectively Y×P6), where Y is a connected surface equipped with a canonical conformal structure and Pn is n-dimensonal real projective space.A corollary is that the only simply-connected compact manifolds which can allow H (respectively O) structure are S4 and S2 × S2 (respectively S8 and S2×S6).Previous authors, for example Marchiafava and Salamon, have studied very closely-related classes of manifolds by differential geometric methods. Our techniques in this paper are function theoretic and topological.


2015 ◽  
Vol 26 (01) ◽  
pp. 1550009 ◽  
Author(s):  
Jianxun Hu ◽  
Wei-Ping Li ◽  
Zhenbo Qin

In this paper, we study the Gromov–Witten theory of the Hilbert schemes X[n] of points on a smooth projective surface X with positive geometric genus pg. For fixed distinct points x1, …, xn-1 ∈ X, let βn be the homology class of the curve {ξ + x2 + ⋯ + xn-1 ∈ X[n] | Supp (ξ) = {x1}}, and let βKX be the homology class of {x + x1 + ⋯ + xn-1 ∈ X[n] | x ∈ KX}. Using cosection localization technique due to Y. Kiem and J. Li, we prove that if X is a simply connected surface admitting a holomorphic differential two-form with irreducible zero divisor, then all the Gromov–Witten invariants of X[n] defined via the moduli space [Formula: see text] of stable maps vanish except possibly when β is a linear combination of βn and βKX. When n = 2, the exceptional cases can be further reduced to the Gromov–Witten invariants: [Formula: see text] with [Formula: see text] and d ≤ 3, and [Formula: see text] with d ≥ 1. When [Formula: see text], we show that [Formula: see text] which is consistent with a well-known formula of C. Taubes. In addition, for an arbitrary surface X and d ≥ 1, we verify that [Formula: see text].


2011 ◽  
Vol 15 (1) ◽  
pp. 499-500 ◽  
Author(s):  
Heesang Park ◽  
Jongil Park ◽  
Dongsoo Shin

2009 ◽  
Vol 13 (2) ◽  
pp. 743-767 ◽  
Author(s):  
Heesang Park ◽  
Jongil Park ◽  
Dongsoo Shin

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