39 citations
6 papers
The degree of the bicanonical map of a surface with
Margarida Mendes Lopes, Rita Pardini
In this note it is shown that, given a smooth minimal complex surface of general type S with p_g(S)=0, K^2_S=3, for which the bicanonical map is a morphism, then the degree of the…
Classification of smooth affine spherical varieties
Friedrich Knop, Bart Van Steirteghem
Let G be a complex reductive group. A normal G-variety X is called spherical if a Borel subgroup of G has a dense orbit in X. Of particular interest are spherical varieties which a…
The conceptualization of time and the constancy of the speed of light
Vasco Guerra, Rodrigo de Abreu
In this work we show that the null result of the Michelson-Morley experiment in vacuum is deeply connected with the notion of time. It can be deduced without any mathematics only f…
Numerical Godeaux surfaces with an involution
Alberto Calabri, Ciro Ciliberto, Margarida Mendes Lopes
Minimal algebraic surfaces of general type with the smallest possible invariants have geometric genus zero and K^2=1 and are usually called "numerical Godeaux surfaces". Although t…
What kind of noncommutative geometry for quantum gravity ?
Pierre Martinetti
We give a brief account of the description of the standard model in noncommutative geometry as well as the thermal time hypothesis, questioning their relevance for quantum gravity.
On Finite Racks and Quandles
Pedro Lopes, Dennis Roseman
We revisit finite racks and quandles using a perspective based on permutations which can aid in the understanding of the structure. As a consequence we recover old results and prov…