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The structure of an even liaison class
(1989)We describe a structure called the LazarsfeldRao property for even liaison classes in projective space. This property holds for many even liaison classes of curves in P3. We give a procedure for showing that an even ... 
A note on the postulation of maximal rank curves
(1987)Let s be the lowest degree of a surface containing a maximal rank curve Y. We want to compare the dimension of the space of the surfaces of degree s containing Y with the dimension of the space of the surfaces of degree ... 
Arithmetically normal sheaves
(1987)We rind the upper bound for the third Chem class of a curvilinear sheaf with seminatural cohomology, and we determine all the triples of Chem classes for which there exist two different kinds of seminatural cohomology. ... 
Deformations of Arithmetically CohenMacaulay subvarieties of Pn
(1989)We show that every arithmetically CohenMacaulay twocodimensional subscheme ofPn can be deformed to a reduced union of twocodimensional linear subvarieties. This problem (classical for curves with the name of Zeuthen ... 
Numerical invariants of rank2 arithmetically buchsbaum sheaves
(1989)We study rank2 reflexive sheaves on P3 whose sections are Buchsbaum curves, giving vanishing theorems for the cohomology and bounds and gaps for the existence range of their Chern classes. These results are applied to ... 
Irreducible families of curves with fixed cohomology
(1989)One of the classical ways for studying the problem of the classification of curves in the projective space was the investigation of the irreducible families of curves, and this approach led to the notion of Hilbert scheme. ...