We describe a method to evaluate multivariate polynomials over a finite field
and discuss its multiplicative complexity.
We show that any complex manifold that has a divisor whose normalization has
non-zero first Betti number either has a non-trivial holomorphic gerbe which
does not trivialize meromorphicly or a meromorphic line bundle not equivalent
to any holomorphic line bundle. Similarly, higher Betti numbers of divisors
correspond to higher gerbes or meromorphic gerbes. We give several new
examples.
In this paper we improve the known bound for the $X$-rank $R_{X}(P)$ of an
element $P\in {\mathbb{P}}^N$ in the case in which $X\subset {\mathbb P}^n$ is
a projective variety obtained as a linear projection from a general
$v$-dimensional subspace $V\subset {\mathbb P}^{n+v}$.
We investigate Koszul cohomology on irreducible nodal curves. In particular,
we prove both Green and Green-Lazarsfeld conjectures for the general k-gonal
nodal curve.
In a recent paper, Gallego, Gonz\'{a}lez and Purnaprajna showed that rational
3-ropes can be smoothed. We generalise their proof and obtain smoothability of
rational $m$-ropes for $m \geq 3$.