Branch-and-Bound Ranked Search by Minimizing Parabolic Polynomials

The Branch-and-Bound Ranked Search algorithm (BRS) is an efficient method for answering top-k queries based on R-trees using multivariate scoring functions. To make BRS effective with ascending rankings, the algorithm must be able to identify lower bounds of the scoring functions for exploring search partitions. This paper presents BRS supporting parabolic polynomials. These functions are common to minimize combined scores over different attributes and cover a variety of applications. To the best of our knowledge the problem to develop an algorithm for computing lower bounds for the BRS method has not been well addressed yet

Reforming the WTO, part 5: how should the burden be shared?

In the last of our series on the challenges facing the World Trade Organisation, Ceylan Inan and Ira Poensgren (LSE) look at the tensions that have emerged between developed and developing countries as they try to agree how to treat each other. The definitions of ‘developed’ and ‘developing’ are contested, not least by the US, which particularly resents the benefits China and India enjoy through their continued status as developing nations

Quasi-Convex Scoring Functions in Branch-and-Bound Ranked Search

For answering top-k queries in which attributes are aggregated to a scalar value for defining a ranking, usually the well-known branch-and-bound principle can be used for efficient query answering. Standard algorithms (e.g., Branch-and-Bound Ranked Search, BRS for short) require scoring functions to be monotone, such that a top-k ranking can be computed in sublinear time in the average case. If monotonicity cannot be guaranteed, efficient query answering algorithms are not known. To make branch-and-bound effective with descending or ascending rankings (maximum top-k or minimum top-k queries, respectively), BRS must be able to identify bounds for exploring search partitions, and only for monotonic ranking functions this is trivial. In this paper, we investigate the class of quasi-convex functions used for scoring objects, and we examine how bounds for exploring data partitions can correctly and efficiently be computed for quasi-convex functions in BRS for maximum top-k queries. Given that quasi-convex scoring functions can usefully be employed for ranking objects in a variety of applications, the mathematical findings presented in this paper are indeed significant for practical top-k query answering

Integrating bank transition planning into prudential supervision

Climate transition plans are a versatile new tool for use by financial and non-financial firms, policymakers and prudential regulators. For banks, they are an important building block that supports their ability to respond adequately to short-, medium- and long-term risks arising from climate change. For central banks and prudential supervisors, assessing the transition plans and planning practices of banks can help overcome some of the limitations that existing prudential frameworks face when it comes to climate change risks, in particular by supporting the assessment of business models and the adequacy of banks internal governance and risk management. This report’s analysis is designed to support prudential authorities across jurisdictions as they integrate transition plans into their supervisory review and evaluation processes. It articulates how the different aspects of the emerging transition plan governance ecosystem fit together, summarises their common elements, and explains the role that prudential supervision should play within this ecosystem. It develops a framework for identifying how specific elements of transition plans can be integrated into existing supervisory assessment procedures, with a primary focus on climate transition plans

Reforming the WTO, part 3: how can its rules be made more flexible?

The UK may end up with a no-deal, ‘WTO Brexit’. WTO members want more flexibility in rule-making. But this has hitherto been impossible to achieve across the board, so members have pursued smaller-scale agreements that ultimately undermine the WTO’s cohesion. Jacqueline Maldonado Ortega and Ira Poensgen (LSE) propose a different approach

Self-diffusion of adatoms, dimers, and vacancies on Cu(100)

We use ab initio static relaxation methods and semi-empirical molecular-dynamics simulations to investigate the energetics and dynamics of the diffusion of adatoms, dimers, and vacancies on Cu(100). It is found that the dynamical energy barriers for diffusion are well approximated by the static, 0 K barriers and that prefactors do not depend sensitively on the species undergoing diffusion. The ab initio barriers are observed to be significantly lower when calculated within the generalized-gradient approximation (GGA) rather than in the local-density approximation (LDA). Our calculations predict that surface diffusion should proceed primarily via the diffusion of vacancies. Adatoms are found to migrate most easily via a jump mechanism. This is the case, also, of dimers, even though the corresponding barrier is slightly larger than it is for adatoms. We observe, further, that dimers diffuse more readily than they can dissociate. Our results are discussed in the context of recent submonolayer growth experiments of Cu(100).Comment: Submitted to the Physical Review B; 15 pages including postscript figures; see also http://www.centrcn.umontreal.ca/~lewi

Climate needs to go back into the Treasury's remit letters

The remit letters to be sent by the Chancellor on November 14 to the Bank of England and Financial Conduct Authority are a critical opportunity to re-establish that these bodies should have regard for the Government’s climate and environmental ambitions, write Irene Claeys, Ira Poensgen, David Barmes and Agnieszka Smolenska. At least once a year, … Continue

Banks and climate litigation risk: navigating the low-carbon transition

Over the past decade, climate-related litigation targeted at both public and private actors has mushroomed. This includes some high-profile cases brought directly against banks. Such litigation trends pose material financial risks to banks. In addition, credit institutions need to manage risks related to the rapidly evolving landscape of climate litigation against corporate clients. How banks identify, manage and mitigate these novel legal risks is of strong relevance from the perspective of prudential policy and the effectiveness of transition policies more broadly. To respond to this challenge, this report investigates how credit institutions engage with climate- and environment-related legal risks. It explains how insights from bank current practice, such as gaps in their legal risk management approaches, should be addressed with targeted prudential policy interventions

Análisis del comportamiento espacio-temporal de los caudales residuales en la cuenca urbana del río Salitre

Ingeniero (a) CivilPregrad