1,721,036 research outputs found
On the classification of numerical Godeaux surfaces with an involution
No full textReport on a work in progress, with M. Mendes Lopes, about the classification of numerical Godeaux surfaces (i.e. minimal algebraic surfaces of general type with vanishing geometric genus and bi-genus equal to 2) with an automorphism of order 2
On the birationality of the bicanonical map of a surface section of a threefold
No full textLet (M,L) be a polarized threefold of log-general type. The birationality of the bicanonical map of a smooth surface S \in |L| is studied. This problem was previously considered and partially solved by the first and the fourth author, who gave a satisfactory classification unless h^1(\Cal O_M)=0 and p_g(S)=3,4,5. This article focuses on the remaining cases which are the hardest, settling the proble
Even sets of four nodes on rational surfaces
No full textWe describe smooth rational projective algebraic surfaces X, over an
algebraically closed field of characteristic different from 2, having an even set of
four disjoint (-2)-curves, i.e. such that the sum of the four curves is divisible by
2 in the Picard group of X
Birational classification of curves on rational surfaces
Get PDFIn this paper we consider the birational classification of pairs (S,L), with S a rational surface and L a linear system on S. We give a classification theorem for such pairs, and we determine, for each irreducible plane curve B, its Cremona minimal models, that is, those plane curves which are equivalent to B via a Cremona transformation and have minimal degree under this condition
Federigo Enriques, The First Years in Bologna
No full textIn this paper, we concentrate on Enriques' first years in Bologna, from 1894 to the turn of the century. More specifically, we consider Enriques' activity relating to his teaching duties in Bologna during those years, showing how the preparation of his Courses stimulated his interest in mathematical and philosophical problems related to the foundations of the discipline
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