Benchmark-adjusted performance of US equity mutual funds and the issue of prospectus benchmarks

This study examines the impact of mismatch between prospectus benchmark and fund objectives on benchmark-adjusted fund performance and ranking in a sample of 1281 US equity mutual funds. All funds in our sample report S&P500 index as a prospectus benchmark, yet 2/3 of those are placed in the Morningstar category with risk and objectives different to those of the S&P500 index. We identify more appropriate ‘category benchmarks’ for those mismatched funds and obtain their benchmark-adjusted alphas using recent Angelidis et al. (J Bank Finance 37(5):1759–1776, 2013) methodology. We find that S&P500-adjusted alphas are higher than ‘category benchmark’-adjusted alphas in 61.2% of the cases. In terms of fund quartile rankings, 30% of winner funds lose that status when the prospectus benchmark is substituted with the one better matching their objectives. In the remaining performance quartiles, there is no clear advantage of using S&P 500 as a benchmark. Hence, the prospectus benchmark can mislead investors about fund’s relative performance and ranking, so any reference to performance in a fund’s prospectus should be treated with caution

An Algorithmic Metatheorem for Directed Treewidth

The notion of directed treewidth was introduced by Johnson, Robertson, Seymour and Thomas [Journal of Combinatorial Theory, Series B, Vol 82, 2001] as a first step towards an algorithmic metatheory for digraphs. They showed that some NP-complete properties such as Hamiltonicity can be decided in polynomial time on digraphs of constant directed treewidth. Nevertheless, despite more than one decade of intensive research, the list of hard combinatorial problems that are known to be solvable in polynomial time when restricted to digraphs of constant directed treewidth has remained scarce. In this work we enrich this list by providing for the first time an algorithmic metatheorem connecting the monadic second order logic of graphs to directed treewidth. We show that most of the known positive algorithmic results for digraphs of constant directed treewidth can be reformulated in terms of our metatheorem. Additionally, we show how to use our metatheorem to provide polynomial time algorithms for two classes of combinatorial problems that have not yet been studied in the context of directed width measures. More precisely, for each fixed $k,w \in \mathbb{N}$, we show how to count in polynomial time on digraphs of directed treewidth $w$, the number of minimum spanning strong subgraphs that are the union of $k$ directed paths, and the number of maximal subgraphs that are the union of $k$ directed paths and satisfy a given minor closed property. To prove our metatheorem we devise two technical tools which we believe to be of independent interest. First, we introduce the notion of tree-zig-zag number of a digraph, a new directed width measure that is at most a constant times directed treewidth. Second, we introduce the notion of $z$-saturated tree slice language, a new formalism for the specification and manipulation of infinite sets of digraphs.Comment: 41 pages, 6 figures, Accepted to Discrete Applied Mathematic

On the complexity of finding the maximum entropy compatible quantum state

Herein we study the problem of recovering a density operator from a set of compatible marginals, motivated from limitations of physical observations. Given that the set of compatible density operators is not singular, we adopt Jaynes' principle and wish to characterize a compatible density operator with maximum entropy. We first show that comparing the entropy of compatible density operators is QSZK-complete, even for the simplest case of 3-chains. Then, we focus on the particular case of quantum Markov chains and trees and establish that for these cases, there exists a quantum polynomial circuit that constructs the maximum entropy compatible density operator. Finally, we extend the Chow-Liu algorithm to the same subclass of quantum states.Comment: 21 pages, 2 figure

Education and development in early childhood in two portuguese cultural contexts: the mainland and Azores

The various aspects of a child’s development (physical, psychological, emotional, relational, cognitive, linguistic, perceptive, and motor), as well as the child’s needs and attitudes, are key throughout his/her life and have been studied over the years by various researchers. We will examine the similarities and differences observed in the education and stimulation of children in two cultural contexts: on the Portuguese mainland (Lisbon, Almada, Santarém, Almeirim, and Portalegre regions) and Azorean islands (São Miguel, Pico, and Terceira). Our research focussed on children’s upbringing and development in the following areas: food and hygiene; cognitive and linguistic development; perceptual and motor development; emotional and relational development; sleep; and play and childcare practices. We identify several aspects that contribute to children’s positive physical and psychological development in the first two years of life, both on the mainland and in the Azores, examining aspects, such as sensory stimulation, sleep, types of play, and toys.info:eu-repo/semantics/publishedVersio