scholarly journals Field of moduli versus field of definition for cyclic covers of the projective line

2009 ◽  
Vol 21 (3) ◽  
pp. 679-693 ◽  
Author(s):  
Aristides Kontogeorgis
2006 ◽  
Vol 121 (1) ◽  
pp. 105-130 ◽  
Author(s):  
Jannis A. Antoniadis ◽  
Aristides Kontogeorgis

2020 ◽  
Vol 27 (02) ◽  
pp. 247-262
Author(s):  
Eslam Badr

A Riemann surface [Formula: see text] having field of moduli ℝ, but not a field of definition, is called pseudo-real. This means that [Formula: see text] has anticonformal automorphisms, but none of them is an involution. A Riemann surface is said to be plane if it can be described by a smooth plane model of some degree d ≥ 4 in [Formula: see text]. We characterize pseudo-real-plane Riemann surfaces [Formula: see text], whose conformal automorphism group Aut+([Formula: see text]) is PGL3(ℂ)-conjugate to a finite non-trivial group that leaves invariant infinitely many points of [Formula: see text]. In particular, we show that such pseudo-real-plane Riemann surfaces exist only if Aut+([Formula: see text]) is cyclic of even order n dividing the degree d. Explicit families of pseudo-real-plane Riemann surfaces are given for any degree d = 2pm with m > 1 odd, p prime and n = d/p.


2005 ◽  
Vol 8 ◽  
pp. 102-115 ◽  
Author(s):  
J. Gutierrez ◽  
T. Shaska

AbstractThe purpose of this paper is to study hyperelliptic curves with extra involutions. The locusLgof such genus-ghyperelliptic curves is ag-dimensional subvariety of the moduli space of hyperelliptic curvesHg. The authors present a birational parameterization ofLgvia dihedral invariants, and show how these invariants can be used to determine the field of moduli of points p ∈ Lg. They conjecture that for p ∈Hgwith |Aut(p)| > 2, the field of moduli is a field of definition, and they prove this conjecture for any point p ∈Lgsuch that the Klein 4-group is embedded in the reduced automorphism group ofp. Further, forg= 3, they show that for every moduli point p ∈H3such that |Aut(p)| > 4, the field of moduli is a field of definition. A rational model of the curve over its field of moduli is provided.


2019 ◽  
Vol 5 (1) ◽  
Author(s):  
Wanlin Li ◽  
Elena Mantovan ◽  
Rachel Pries ◽  
Yunqing Tang

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