The cartography of computational search spaces

This talk will present our recent findings and visual (static and animated) maps characterising combinatorial and computer program search spaces. We seek to lay the foundations for a new perspective to understand problem structure and improve heuristic search algorithms: search space cartography.   Heuristic methods operate by searching a large space of candidate solutions. The search space can be regarded as a spatial structure where each point (candidate solution) has a height (objective or fitness value) forming a fitness landscape surface. The performance of search algorithms crucially depends on the fitness landscape structure, and the study of landscapes offers an alternative to problem understanding where realistic formulations and algorithms can be analysed.   Most fitness landscapes analysis techniques study the local structure of search spaces. Our recently proposed model, Local Optima Networks, helps to study instead their global structure. This graph-based model provides fundamental new insight into the structural organisation and the connectivity pattern of a search space with given move operators.  Most importantly, it allows us to visualise realistic search spaces in ways not previously possible and brings a whole new set of network metrics for characterising them. Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Disintegrating Customary International Law: Reactions to Withdrawing from International Custom

Withdrawing from International Custom, a recent article by Curtis Bradley and Mitu Gulati, has sparked interest and debate. Bradley and Gulati’s article, develops with significant nuance and detail that, naturally, can be best understood by a careful reading of their work. In essence, it proposes a modification in customary international law (CIL) doctrine – a change that would permit states to unilaterally exit from existing customary international law. This Essay will act as a brief reflection on that article. In Part I, it will explore the analogies Withdrawing makes between CIL and contract and will argue, first that CIL and contract are not analogous and, second, that even to the extent that contract demonstrates how other doctrinal areas order exits from legal relationships, contract illustrates the point that unilateral exit is a recognized abdication of the exiting party’s obligations and that exit gives rise to legal liability. In Part II, it explores the analogies Withdrawing makes between governments and agents in order to unpack some of the theoretical political theory constructs on which Withdrawing relies, and to explore the limitations Withdrawing sets on the proposal for unilateral exit. Part III of this Essay will make an affirmative argument for symmetry between CIL formation doctrine and CIL disintegration doctrine. The current proposal anticipates that CIL formation would remain unchanged, but exit for any given state would be far more expeditious than is contemplated by current CIL exit formulations. This Part will illustrate that this proposal violates a strong presumption in favor of symmetrical entrenchment

Panentheistic Elements in Wolfhart Pannenberg's Notion of God

In his exposition, Pannenberg dialectically explores the possibility of a redefinition of the notion of God and rejects the anthropomorphic analogies and the Greek understanding of God as nous in order to emphasize the idea of God as Spirit and thus facilitate the intersection between the natural sciences and Christian theology. Thus, based on the Hebrew notion of the spirit as “wind/breath” and using a naturalistic framework, Pannenberg offers an insightful yet panentheistic view of the Spirit of God as a field of force that binds the Three Persons of the Trinity

Interpreting an Affine Term Structure Model for Chile

This paper attempts to provide an economic interpretation of the factors that drive the movements of interest rates of bonds of different maturities in a continuous-time no-arbitrage term structure model for Chile. The dynamics of yields in the model are explained by two latent factors, namely the instantaneous short rate and its time-varying central tendency. The model estimates suggest that the short end of the yield curve is mainly driven by changes in first latent factor, while long-term interest rates are mainly explained by the second latent factor. Consequently, when examining movements in the term structure, one should think of at least two forces that hit the economy: temporary shocks that change short-term and medium-term interest rates by much larger amounts than long-term interest rates, causing changes in the slope of the yield curve; and long-lived innovations which have persistent effects on the level of the yield curve.

Spin-Orbit mediated spin relaxation in monolayer MoS2

We study the intra-valley spin-orbit mediated spin relaxation in monolayers of MoS2 within a two bands effective Hamiltonian. The intrinsic spin splitting of the valence band as well as a Rashba-like coupling due to the breaking of the out-of-plane inversion symmetry are considered. We show that, in the hole doped regime, the out-of-plane spin relaxation is not very efficient since the spin splitting of the valence band tends to stabilize the spin polarization in this direction. We obtain spin lifetimes larger than nanoseconds, in agreement with recent valley polarization experiments.Comment: final version, 9 pages, 5 figure

Generalized Voigt broadening due to thermal fluctuations of electromechanical nanosensors and molecular electronic junctions

Graphene and other 2D materials give a platform for electromechanical sensing of biomolecules in aqueous, room temperature environments. The electronic current changes in response to mechanical deflection, indicating the presence of forces due to interactions with, e.g., molecular species. We develop illustrative models of these sensors in order to give explicit, compact expressions for the current and signal-to-noise ratio. Electromechanical structures have an electron transmission function that follows a generalized Voigt profile, with thermal fluctuations giving a Gaussian smearing analogous to thermal Doppler broadening in solution/gas-phase spectroscopic applications. The Lorentzian component of the profile comes from the contact to the electrodes. After providing an accurate approximate form of this profile, we calculate the mechanical susceptibility for a representative two-level bridge and the current fluctuations for electromechanical detection. These results give the underlying mechanics of electromechanical sensing in more complex scenarios, such as graphene deflectometry

An Interpretation of An Affine Term Structure Model for Chile

This paper attempts to provide an economic interpretation of the factors that drive the movements of interest rates of bonds of different maturities in a continuous-time no arbitrage term structure model for Chile. The dynamics of yields in the model are explained by two latent factors, namely the instantaneous short rate and its time-varying central tendency. The model estimates suggest that the short end of the yield curve is mainly driven by changes in first latent factor, while long-term interest rates are mainly explained by the second latent factor. Consequently, when examining movements in the term structure, one should think of at least two forces that hit the economy: temporary shocks that change short-term and medium-term interest rates by much larger amounts than long-term interest rates, causing changes in the slope of the yield curve; and long-lived innovations which have persistent effects on the level of the yield curve.Affine term structure model; yield curve; Kalman filter