Publications (12)0 Total impact
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Shouhei Ma
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ABSTRACT: We prove that the moduli space of tetragonal curves of genus g>6 is rational
when g is congruent to 1, 2, 5, 6, 9, 10 modulo 12 and not equal to 9, 45.
02/2013;
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ABSTRACT: K3 surfaces with non-symplectic symmetry of order 3 are classified by open
sets of twenty-four complex ball quotients associated to Eisenstein lattices.
We show that twenty-two of those moduli spaces are rational.
08/2012;
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Shouhei Ma
07/2012;
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Shouhei Ma
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ABSTRACT: We prove that the quotient by SL(2)\timesSL(2) of the space of bidegree (a,
b) curves on P^1\timesP^1 is rational when ab is even and a\not=b.
02/2012;
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Shouhei Ma
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ABSTRACT: K3 surfaces with non-symplectic involution are classified by open sets of
seventy-five arithmetic quotients of type IV. We prove that those moduli spaces
are rational except two classical cases.
10/2011;
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Shouhei Ma
12/2010;
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Shouhei Ma
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ABSTRACT: We prove that the moduli spaces of K3 surfaces with non-symplectic
involutions are unirational. As a by-product we describe configuration spaces
of 4<d<9 points in the projective plane as arithmetic quotients of type IV.
11/2010;
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Shouhei Ma
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ABSTRACT: When a complex Abelian surface can be decomposed into a product of two elliptic curves, how many decompositions does the Abelian surface admit ? We provide arithmetic formulae for the number of decompositions of a complex Abelian surface. Comment: 27 pages
06/2009;
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Shouhei Ma
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ABSTRACT: We study isogeny relations between K3 surfaces and Kummer surfaces.
Specifically, we prove a Torelli-type theorem for the existence of rational
maps from K3 surfaces to Kummer surfaces, and a Kummer sandwich theorem for K3
surfaces with Shioda-Inose structure.
05/2009;
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Shouhei Ma
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ABSTRACT: Let S be a projective K3 surface. It is proved that the 0-dimensional cusps of the Kahler moduli of S are in one-to-one correspondence with the twisted Fourier-Mukai partners of S. This leads to a counting formula for the 0-dimensional cusps of the Kahler moduli. Applications to rational maps between K3 surfaces with large Picard numbers are given. When the Picard number of S is 1, the bijective correspondence is calculated explicitly. Comment: 24pages
12/2008;
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Shouhei Ma
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ABSTRACT: We give a counting formula for the twisted Fourier-Mukai partners of a projective K3 surface. As an application, we describe all twisted Fourier-Mukai partners of a projective K3 surface of Picard number 1.
05/2008;
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Shouhei Ma
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ABSTRACT: Using lattice theory, we establish a one-to-one correspondence between the set of Fourier-Mukai partners of a projective $K3$ surface and the set of 0-dimensional standard cusps of its Kahler moduli. We also study the relation between twisted Fourier-Mukai partners and general 0-dimensional cusps, and the relation between Fourier-Mukai partners with elliptic fibrations and certain 1-dimensional cusps.
05/2008;