Approximation algorithms and hardness results for labeled connectivity problems

Let G=(V,E) be a connected multigraph, whose edges are associated with labels specified by an integer-valued function ℒ:E→ℕ. In addition, each label ℓ∈ℕ has a non-negative cost c(ℓ). The minimum label spanning tree problem (MinLST) asks to find a spanning tree in G that minimizes the overall cost of the labels used by its edges. Equivalently, we aim at finding a minimum cost subset of labels I⊆ℕ such that the edge set {e∈E:ℒ(e)∈I} forms a connected subgraph spanning all vertices. Similarly, in the minimum label s – t path problem (MinLP) the goal is to identify an s–t path minimizing the combined cost of its labels. The main contributions of this paper are improved approximation algorithms and hardness results for MinLST and MinLP.     

Population Growth and the Local Provision of Services: The Role of Primary Schools in Portugal

Population Research and Policy Review - The shrinking population in many European regions has led to a debate on the relation between the local provision of services of general interest and the...     

The Experience of Learning EFT in Spanish-speaking Countries: A Multi-National Replication Study

This study is a multi-national follow-up to the original (Sandberg and Knestel (2011) Journal of Marital and Family Therapy, 37, 393–410) article on the process of learning Emotionally Focused Couples Therapy (EFT). A total of 102 clinicians from nine Spanish-speaking countries (Mexico, Costa Rica, Guatemala, Spain, Colombia, Argentina, Chile, Ecuador, and El Salvador) participated in the study. A comparison of results across the two studies revealed more similarities than differences. However, a few notable differences emerged from responses to qualitative questions, namely a heightened sense of appreciation for and resonance with the focus on core emotion in EFT and less frequent reports of difficulty learning and adapting to the model among Spanish-speaking therapists. These differences were consistent with common cultural values and forms of expression in Latin America and Spain. Results are discussed in terms of training, supervision, and future research as well.     

Urbanization homogenizes the interactions of plant-frugivore bird networks

Urban Ecosystems - Anthropogenic activities are the main cause of habitat loss and fragmentation, which directly affects biodiversity. Disruption in landscape connectivity among populations may...     

Entrepreneurship research: mapping intellectual structures and research trends

Review of Managerial Science - Using bibliometric techniques to identify connections between existing entrepreneurship studies, this article seeks to understand the scientific structure of...