On jumping lines of vector bundles on Pn

We give bounds on the rank of non uniform vector bundles on Pn with a finite number of jumping lines

Quasi-complete intersections in P2 and syzygies

Let C⊂ P2 be a reduced, singular curve of degree d and equation f= 0. Let Σ denote the jacobian subscheme of C. We have 0 → E→ 3. O→ IΣ(d- 1) → 0 (the surjection is given by the partials of f). We study the relationships between the Betti numbers of the module H∗0(E) and the integers, d, τ, where τ= deg (Σ). We observe that our results apply to any quasi-complete intersection of type (s, s, s)

The maximal genus of space curves in the range A

For large d we prove the so called maximal genus conjecture in the range

On the Hilbert scheme of curves in higher-dimensional projective space

In this paper we prove that, for any $n\ge 3$, there exist infinitely many $r\in \N$ and for each of them a smooth, connected curve $C_r$ in $\P^r$ such that $C_r$ lies on exactly $n$ irreducible components of the Hilbert scheme \hilb(\P^r). This is proven by reducing the problem to an analogous statement for the moduli of surfaces of general type.Comment: latex, 12 pages, no figure

Pemanfaatan Ncb Dan Cbtl Oleh Produsen Elektroteknika Di Indonesia

Since 2005 BSN represent Indonesia as a member body in the IECEE. Up to now, Indonesia has 3 NCB and 4 CBTL which has received recognition to operate within the IECEE CB Scheme, however the potential for NCB and CBTL is not used optimally by the electrical engineering product manufacturer located in Indonesia. Based on the statistical data of CB Test Certificate (CBTC), until 2012, there are only 4 certificates issued by the NCB in Indonesia (Teguh et al, 2014). The aim of the research was to determine the characteristics of the producers that act as significant factors affecting the utilization of National NCB and CBTL. Hypothesis of this study is the character that affect the utilization were: (1) "Capital" for the status of foreign / domestic investment, (2) "Knowledge" for producers' knowledge to availability of NCB and CBTL in Indonesia, (3) "awareness" for awareness of the company to benefits if NCB and CBTL available in Indonesia, (4) "suitability" for NCB and CBTL scope suitability compared to producers' products, and (5) "Determinant" for party who deciding the election NCB and CBTL. This study used descriptive quantitative method, direct interviews with respondents, multiple regression analysis and correlation. Respondents were selected based on following criterias: (1) listed in CBTC statistical data, (2) located in Indonesia, and (3) product manufacturers have the same scope with the scope of the national NCB (HOUS, LITE, INST and BATT), expanded with TRON and OFF that the statistics dominate the CBTC in Indonesia and the world. 28 respondents were obtained, with 95% of confidence level for representing it population. Conclusion of the research was the five factors tested contribute strongly to the selection of NCB and CBTL by 78.2%, with positive correlation. Three factors with significance <0.15 were "determinant", "suitability", and "knowledge"

Spaces of matrices of constant rank and uniform vector bundles

We consider the problem of determining l(r,a) , the maximal dimension of a subspace of axa matrices of rank r. We first review (and reprove) in the language of vector bundles the known results. Then using known facts on uniform vectro bundles we prove some new results and make a conjecture. We determine l(r,a) for every r when a <= 10, proving in this case our conjecture

Quasi-complete intersections and global Tjurina number of plane curves

A closed subscheme of codimension two T⊂P2 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)→IT. We give bounds on deg⁡(T) in function of a,b,c and r, the least degree of a syzygy between the three polynomials defining the q.c.i. (see Theorem 6). As a by-product we recover a theorem of du Plessis-Wall on the global Tjurina number of plane curves (see Theorem 20) and some other related results

Codimension two subvarieties and related questions

A survey of codimension 2 subvarieties, related to Hartshorne Conjecture

Global Generation

condizioni affinche' il fascio d'ideali di una curva di P3 sia generato dalle sezioni global