The following problem was posed by C.A. Nicol: given any finite sequence of positive integers, find the permutation for which the continuant (i.e. the continued fraction denominator) having these entries is maximal, resp. minimal. The extremal arrangements are known for the regular continued fraction expansion. For the singular expansion induced by the backward shift d1/xe − 1/x the problem is ...

In contrast to the extremal variants of coNP-complete problems, which are frequently DP-complete, many extremal variants of NP-complete problems are in P. We investigate the extremal variants of two NP-complete problems, the extremal colorability problem with restricted degree and the extremal unfrozen non-implicant problem, and show that both of them are DP-complete. As far as we know, no extr...

We review some aspects of the attractor mechanism for extremal black holes of (not necessarily supersymmetric) theories coupling Einstein gravity to scalars and Maxwell vector fields. Thence, we consider N = 2 and N = 8, d = 4 supergravities, reporting some recent advances on the moduli spaces associated to BPS and nonBPS attractor solutions supported by charge orbits with non-compact stabilize...

We present a method for tracking Maximally Stable Homogeneous Regions (MSHR) in images with an arbitrary number of channels. MSHR are conceptionally very similar to Maximally Stable Extremal Regions (MSER) and Maximally Stable Color Regions (MSCR), but can also be applied to hyperspectral and color images while remaining extremely efficient. The presented approach makes use of the edge-based co...

A symmetric subset of the reals is one that remains invariant under some reflection x 7→ c − x. We consider, for any 0 < ε ≤ 1, the largest real number ∆(ε) such that every subset of [0, 1] with measure greater than ε contains a symmetric subset with measure ∆(ε). In this paper we establish upper and lower bounds for ∆(ε) of the same order of magnitude: for example, we prove that ∆(ε) = 2ε − 1 ...

We prove several results from different areas of extremal combinatorics, giving complete or partial solutions to a number of open problems. These results, coming from areas such as extremal graph theory, Ramsey theory and additive combinatorics, have been collected together because in each case the relevant proofs are quite short.

A 0-1 matrix is a matrix in which every element is either 0 or 1. The weight extremal function ex(n, P ) counts the maximum number of 1’s in an n × n matrix which avoids a pattern matrix P . The column extremal function exk(m,P ) counts the maximum number of columns that a matrix with m rows and k 1’s per column can contain such that the matrix avoids P . Set weight and column extremal function...

In this paper we introduce the notion of s-extremal lattice for unimodular Type I lattices. We give a bound on the existence of certain such s-extremal lattices: an s-extremal lattice of dimension n and minimal even norm μ must satisfy n < 12μ. This result implies that such lattices are also extremal and that there are a finite number of them. We also give an equivalent bound for s-extremal sel...

The theory of Finsler metric was introduced by Paul Finsler, in 1918. author defines this using the Minkowski norm instead inner product. Therefore, geometry is a more general and includes Riemannian metric. In present work, metric, we investigate position vector rectifying, normal osculating curves Finslerian 3-space $\mathbb{F}^{3}$. We obtain characterizations these Furthermore, show that re...

In this paper, binary extremal self-dual codes of length 48 and extremal unimodular lattices in dimension 48 are studied through their shadows and neighbors. We relate an extremal singly even self-dual [48, 24, 10] code whose shadow has minimum weight 4 to an extremal doubly even selfdual [48, 24, 12] code. It is also shown that an extremal odd unimodular lattice in dimension 48 whose shadow ha...