Browsing Bergen Open Research Archive by Author "Knutsen, Andreas Leopold"
Now showing items 112 of 12

Brill–Noether general K3 surfaces with the maximal number of elliptic pencils of minimal degree
Hoff, Michael; Knutsen, Andreas Leopold (Journal article; Peer reviewed, 2020)We explicitly construct Brill–Noether general K3 surfaces of genus 4, 6 and 8 having the maximal number of elliptic pencils of degrees 3, 4 and 5, respectively, and study their moduli spaces and moduli maps to the moduli ... 
Elliptic curves, ACM bundles and Ulrich bundles on prime Fano threefolds
Ciliberto, Ciro; Flamini, Flaminio; Knutsen, Andreas Leopold (Journal article; Peer reviewed, 2023)Let X be any smooth prime Fano threefold of degree 2g−2 in Pg+1 , with g ∈ {3, . . . , 10, 12}. We prove that for any integer d satisfying ⌊ g+3 2 ⌋ d g+3 the Hilbert scheme parametriz ing smooth irreducible elliptic ... 
Genus two curves on abelian surfaces
Knutsen, Andreas Leopold; LelliChiesa, Margherita (Journal article; Peer reviewed, 2022)This paper deals with singularities of genus 2 curves on a general (d1, d2) polarized abelian surface (S, L). In analogy with Chen’s results concerning rational curves on K3 surfaces [Ch1, Ch2], it is natural to ask whether ... 
Global sections of twisted normal bundles of K3 surfaces and their hyperplane sections
Knutsen, Andreas Leopold (Journal article; Peer reviewed, 2020)Let S⊂Pg be a smooth K3 surface of degree 2g−2, g≥3. We classify all the cases for which h0(NS/Pg(−2))≠0 and the cases for which h0(NS/Pg(−2))<h0(NC/Pg−1(−2)) for C⊂Pg−1 a general canonical curve section of S. 
Irreducible unirational and uniruled components of moduli spaces of polarized Enriques surfaces
Ciliberto, Ciro; Dedieu, Thomas; Galati, Concettina; Knutsen, Andreas Leopold (Journal article; Peer reviewed, 2023)We prove that infinitely many irreducible components of the moduli space of polarized Enriques surfaces are unirational (resp. uniruled), characterizing them in terms of decompo sitions of the polarization as an effective ... 
Moduli of curves on Enriques surfaces
Knutsen, Andreas Leopold; Ciliberto, Ciro; Dedieu, Thomas; Galati, Concettina (Journal article; Peer reviewed, 2020)We compute the number of moduli of all irreducible components of the moduli space of smooth curves on Enriques surfaces. In most cases, the moduli maps to the moduli space of Prym curves are generically injective or dominant. ... 
Moduli of nonstandard Nikulin surfaces in low genus
Knutsen, Andreas Leopold; LelliChiesa, Margherita; Verra, Alessandro (Journal article; Peer reviewed, 2020)Primitively polarized genus g Nikulin surfaces (S, M, H) are of two types, that we call standard and nonstandard depending on whether the lattice embedding Z[H] ⊕⊥ N ⊂ Pic S is primitive. Here H is the genus g polarization ... 
Nonemptiness of severi varieties on enriques surfaces
Ciliberto, Ciro; Dedieu, Thomas; Galati, Concettina; Knutsen, Andreas Leopold (Journal article; Peer reviewed, 2023)Let (S,L) be a general polarised Enriques surface, with L not numerically 2divisible. We prove the existence of regular components of all Severi varieties of irreducible nodal curves in the linear system L , that is, ... 
A note on Severi varieties of nodal curves on Enriques surfaces
Knutsen, Andreas Leopold; Ciliberto, Ciro; Dedieu, Thomas; Galati, Concettina (Journal article; Peer reviewed, 2020)Let L be a linear system on a smooth complex Enriques surface S whose general member is a smooth and irreducible curve of genus p, with L2 > 0, and let VL,δ(S) be the Severi variety of irreducible δnodal curves in ... 
On moduli spaces of polarized Enriques surfaces
Knutsen, Andreas Leopold (Journal article; Peer reviewed, 2020)We prove that, for any g≥2, the étale double cover ρg:Eg→̂Eg from the moduli space Egof complex polarized genus g Enriques surfaces to the moduli space ̂Egof numerically polarized genus g Enriques surfaces is disconnected ... 
Severi varieties on blowups of the symmetric square of an elliptic curve
Ciliberto, Ciro; Dedieu, Thomas; Galati, Concettina; Knutsen, Andreas Leopold (Journal article; Peer reviewed, 2023)We prove that certain Severi varieties of nodal curves of positive genus on general blowups of the twofold symmetric product of a general elliptic curve are nonempty and smooth of the expected dimension. This result, ... 
Ulrich bundles on a general blowup of the plane
Ciliberto, Ciro; Flamini, Flaminio; Knutsen, Andreas Leopold (Journal article; Peer reviewed, 2023)We prove that on X n , the plane blownup at n very general points, there are Ulrich line bundles with respect to a line bundle corresponding to curves of degree m passing simply through the n blownup points, with m ≤ 2√n ...