Zobrazeno 1 - 10
of 46
pro vyhledávání: '"Ph. Ellia"'
Autor:
Ph. Ellia
Publikováno v:
Journal of Pure and Applied Algebra. 224:423-431
A closed subscheme of codimension two T ⊂ P 2 is a quasi complete intersection (q.c.i.) of type ( a , b , c ) if there exists a surjective morphism O ( − a ) ⊕ O ( − b ) ⊕ O ( − c ) → I T . We give bounds on deg ( T ) in function of
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::7e564fd88da400da8d34aeef809f1350
https://doi.org/10.1016/j.jpaa.2019.05.014
https://doi.org/10.1016/j.jpaa.2019.05.014
Autor:
Ph. Ellia
Publikováno v:
Rendiconti del Circolo Matematico di Palermo Series 2. 69:813-822
Let $$C \subset {\mathbb {P}}^2$$ be a reduced, singular curve of degree d and equation $$f=0$$ . Let $$\Sigma $$ denote the jacobian subscheme of C. We have $$0 \rightarrow E \rightarrow 3.\mathcal {O}\rightarrow \mathcal {I}_\Sigma (d-1) \rightarro
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::fc8e060b2fd514fba3a1d7a458d76338
https://doi.org/10.1007/s12215-019-00437-w
https://doi.org/10.1007/s12215-019-00437-w
Publikováno v:
Mathematische Zeitschrift. 251:257-265
We prove that a smooth, subcanonical surface of P^4 (projective space over an algebraically closed field of characteristic zero) is complete intersection if it is contained in a quartic hypersurface.
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::0deb13234b4f405c14f084a7cf25ddfa
https://doi.org/10.1007/s00209-005-0796-7
https://doi.org/10.1007/s00209-005-0796-7
Autor:
C. Folegatti, Ph. Ellia
Publikováno v:
Communications in Algebra. 32:707-713
We prove that there exists an integer M such that if S ⊂ ℙ4 is a smooth surface with deg(S) > M, then the canonical map of S is birational. Then we consider surfaces, S, satisfying h i (ℐ S (3 − i)) = 0, 0 ≤ i ≤ 2 and show that they are r
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::15e7e9ae27bd2937e026a341c9f07ce0
https://doi.org/10.1081/agb-120027924
https://doi.org/10.1081/agb-120027924
Autor:
Ph. Ellia
Publikováno v:
International Journal of Mathematics. 14:529-539
The lifting invariants of a closed subscheme X ⊂ Pn are the numbers [Formula: see text], where H is a general hyperplane and where f is the restriction map. The lifting invariants measure the obstruction to lift hypersurfaces (of H) containing X
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::8b4720cfcf5acfbebfcd6ee7896805e6
https://doi.org/10.1142/s0129167x03001843
https://doi.org/10.1142/s0129167x03001843
Autor:
Ph. Ellia, Davide Franco
Publikováno v:
Journal of Algebraic Geometry. 11:513-533
We prove the following: Theorem. Let X ⊂ P 5 X\subset \mathbf {P}^5 be a smooth, subcanonical threefold. If h 0 ( I X ( 4 ) ) ≠ 0 h^0(\mathcal {I}_X(4))\ne 0 , then X X is a complete intersection. Let X ⊂ P 6 X\subset \mathbf {P}^6 be a smooth,
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::70edef01b26ef9757a194f477fb0cc0e
https://doi.org/10.1090/s1056-3911-02-00320-x
https://doi.org/10.1090/s1056-3911-02-00320-x
Autor:
Ph. Ellia
Publikováno v:
Journal of Pure and Applied Algebra. 152(1-3):83-88
In this paper we show that a smooth rational surface in P 4 ruled in cubics or quartics (i.e. possessing a base point free pencil of rational curves of degree three or four in P 4 ) has degree d ≤12. As a corollary it is shown that if S⊂ P 4 is t
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::863491d44765f2c2ff628a16c484c759
Autor:
Ph. Ellia, A. C. De Candia
Publikováno v:
ANNALI DELL UNIVERSITA DI FERRARA. 43:135-156
We classify smooth subvarieties of codimension twoX⊂P n , 4≤n≤5, which are arithmetically Cohen-Macaulay and of non general type. By the way we exhibit some classes of non extendable subvarieties. Then we give new proofs of the classification o
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::7c2e7acb449d2808185dd554ff921d89
https://doi.org/10.1007/bf02837231
https://doi.org/10.1007/bf02837231
Autor:
A. Dolcetti, Ph. Ellia
Publikováno v:
Communications in Algebra. 23:4261-4273
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::22ae981ad216dc85f10e73fb16caf109
https://doi.org/10.1080/00927879508825463
https://doi.org/10.1080/00927879508825463
Autor:
Ph. Ellia
Publikováno v:
ANNALI DELL'UNIVERSITA' DI FERRARA. 38:217-227
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::363ef65af35288afda8bf0bd3e099f43
https://doi.org/10.1007/bf02827092
https://doi.org/10.1007/bf02827092