Abstraction Heuristics, Cost Partitioning and Network Flows

Cost partitioning is a well-known technique to make admissible heuristics for classical planning additive. The optimal cost partitioning of explicit-state abstraction heuristics can be computed in polynomial time with a linear program, but the size of the model is often prohibitive. We study this model from a dual perspective and develop several simplification rules to reduce its size. We use these rules to answer open questions about extensions of the state equation heuristic and their relation to cost partitioning

Higher-Dimensional Potential Heuristics for Optimal Classical Planning

Potential heuristics for state-space search are defined as weighted sums over simple state features. Atomic features consider the value of a single state variable in a factored state representation, while binary features consider joint assignments to two state variables. Previous work showed that the set of all admissible and consistent potential heuristics using atomic features can be characterized by a compact set of linear constraints. We generalize this result to binary features and prove a hardness result for features of higher dimension. Furthermore, we prove a tractability result based on the treewidth of a new graphical structure we call the context-dependency graph. Finally, we study the relationship of potential heuristics to transition cost partitioning. Experimental results show that binary potential heuristics are significantly more informative than the previously considered atomic ones

Heuristics for cost-optimal classical planning based on linear programming

Many heuristics for cost-optimal planning are based on linear programming. We cover several interesting heuristics of this type by a common framework that fixes the objective function of the linear program. Within the framework, constraints from different heuristics can be combined in one heuristic estimate which dominates the maximum of the component heuristics. Different heuristics of the framework can be compared on the basis of their constraints. We present theoretical results on the relation between existing heuristics and experimental results that demonstrate the potential of the proposed framework

The Running of the Cosmological and the Newton Constant controlled by the Cosmological Event Horizon

We study the renormalisation group running of the cosmological and the Newton constant, where the renormalisation scale is given by the inverse of the radius of the cosmological event horizon. In this framework, we discuss the future evolution of the universe, where we find stable de Sitter solutions, but also "big crunch"-like and "big rip"-like events, depending on the choice of the parameters in the model.Comment: 14 pages, 7 figures, minor improvements, references adde

Dynamically avoiding fine-tuning the cosmological constant: the "Relaxed Universe"

We demonstrate that there exists a large class of action functionals of the scalar curvature and of the Gauss-Bonnet invariant which are able to relax dynamically a large cosmological constant (CC), whatever it be its starting value in the early universe. Hence, it is possible to understand, without fine-tuning, the very small current value of the CC as compared to its theoretically expected large value in quantum field theory and string theory. In our framework, this relaxation appears as a pure gravitational effect, where no ad hoc scalar fields are needed. The action involves a positive power of a characteristic mass parameter, M, whose value can be, interestingly enough, of the order of a typical particle physics mass of the Standard Model of the strong and electroweak interactions or extensions thereof, including the neutrino mass. The model universe emerging from this scenario (the "Relaxed Universe") falls within the class of the so-called LXCDM models of the cosmic evolution. Therefore, there is a "cosmon" entity X (represented by an effective object, not a field), which in this case is generated by the effective functional and is responsible for the dynamical adjustment of the cosmological constant. This model universe successfully mimics the essential past epochs of the standard (or "concordance") cosmological model (LCDM). Furthermore, it provides interesting clues to the coincidence problem and it may even connect naturally with primordial inflation.Comment: LaTeX, 63 pp, 8 figures. Extended discussion. Version accepted in JCA

Ser/Thr/Tyr Protein Phosphorylation in the Archaeon Halobacterium salinarum—A Representative of the Third Domain of Life

In the quest for the origin and evolution of protein phosphorylation, the major regulatory post-translational modification in eukaryotes, the members of archaea, the “third domain of life”, play a protagonistic role. A plethora of studies have demonstrated that archaeal proteins are subject to post-translational modification by covalent phosphorylation, but little is known concerning the identities of the proteins affected, the impact on their functionality, the physiological roles of archaeal protein phosphorylation/dephosphorylation, and the protein kinases/phosphatases involved. These limited studies led to the initial hypothesis that archaea, similarly to other prokaryotes, use mainly histidine/aspartate phosphorylation, in their two-component systems representing a paradigm of prokaryotic signal transduction, while eukaryotes mostly use Ser/Thr/Tyr phosphorylation for creating highly sophisticated regulatory networks. In antithesis to the above hypothesis, several studies showed that Ser/Thr/Tyr phosphorylation is also common in the bacterial cell, and here we present the first genome-wide phosphoproteomic analysis of the model organism of archaea, Halobacterium salinarum, proving the existence/conservation of Ser/Thr/Tyr phosphorylation in the “third domain” of life, allowing a better understanding of the origin and evolution of the so-called “Nature's premier” mechanism for regulating the functional properties of proteins

How genomics can help biodiversity conservation

The availability of public genomic resources can greatly assist biodiversity assessment, conservation, and restoration efforts by providing evidence for scientifically informed management decisions. Here we survey the main approaches and applications in biodiversity and conservation genomics, considering practical factors, such as cost, time, prerequisite skills, and current shortcomings of applications. Most approaches perform best in combination with reference genomes from the target species or closely related species. We review case studies to illustrate how reference genomes can facilitate biodiversity research and conservation across the tree of life. We conclude that the time is ripe to view reference genomes as fundamental resources and to integrate their use as a best practice in conservation genomics.info:eu-repo/semantics/publishedVersio

The era of reference genomes in conservation genomics

Progress in genome sequencing now enables the large-scale generation of reference genomes. Various international initiatives aim to generate reference genomes representing global biodiversity. These genomes provide unique insights into genomic diversity and architecture, thereby enabling comprehensive analyses of population and functional genomics, and are expected to revolutionize conservation genomics

The era of reference genomes in conservation genomics

info:eu-repo/semantics/publishedVersio