Categories vs. groupoids via generalised Mal'tsev properties

We study the difference between internal categories and internal groupoids in terms of generalised Mal'tsev properties---the weak Mal'tsev property on the one hand, and $n$-permutability on the other. In the first part of the article we give conditions on internal categorical structures which detect whether the surrounding category is naturally Mal'tsev, Mal'tsev or weakly Mal'tsev. We show that these do not depend on the existence of binary products. In the second part we focus on varieties of algebras.Comment: 30 pages; final published versio

EcoGIS – GIS tools for ecosystem approaches to fisheries management

Executive Summary: The EcoGIS project was launched in September 2004 to investigate how Geographic Information Systems (GIS), marine data, and custom analysis tools can better enable fisheries scientists and managers to adopt Ecosystem Approaches to Fisheries Management (EAFM). EcoGIS is a collaborative effort between NOAA’s National Ocean Service (NOS) and National Marine Fisheries Service (NMFS), and four regional Fishery Management Councils. The project has focused on four priority areas: Fishing Catch and Effort Analysis, Area Characterization, Bycatch Analysis, and Habitat Interactions. Of these four functional areas, the project team first focused on developing a working prototype for catch and effort analysis: the Fishery Mapper Tool. This ArcGIS extension creates time-and-area summarized maps of fishing catch and effort from logbook, observer, or fishery-independent survey data sets. Source data may come from Oracle, Microsoft Access, or other file formats. Feedback from beta-testers of the Fishery Mapper was used to debug the prototype, enhance performance, and add features. This report describes the four priority functional areas, the development of the Fishery Mapper tool, and several themes that emerged through the parallel evolution of the EcoGIS project, the concept and implementation of the broader field of Ecosystem Approaches to Management (EAM), data management practices, and other EAM toolsets. In addition, a set of six succinct recommendations are proposed on page 29. One major conclusion from this work is that there is no single “super-tool” to enable Ecosystem Approaches to Management; as such, tools should be developed for specific purposes with attention given to interoperability and automation. Future work should be coordinated with other GIS development projects in order to provide “value added” and minimize duplication of efforts. In addition to custom tools, the development of cross-cutting Regional Ecosystem Spatial Databases will enable access to quality data to support the analyses required by EAM. GIS tools will be useful in developing Integrated Ecosystem Assessments (IEAs) and providing pre- and post-processing capabilities for spatially-explicit ecosystem models. Continued funding will enable the EcoGIS project to develop GIS tools that are immediately applicable to today’s needs. These tools will enable simplified and efficient data query, the ability to visualize data over time, and ways to synthesize multidimensional data from diverse sources. These capabilities will provide new information for analyzing issues from an ecosystem perspective, which will ultimately result in better understanding of fisheries and better support for decision-making. (PDF file contains 45 pages.

Further remarks on the "Smith is Huq" condition

We compare the 'Smith is Huq' condition (SH) with three commutator conditions in semi-abelian categories: first an apparently weaker condition which arose in joint work with Bourn and turns out to be equivalent with (SH), then an apparently equivalent condition which takes commutation of non-normal subobjects into account and turns out to be stronger than (SH). This leads to the even stronger condition that weighted commutators (in the sense of Gran, Janelidze and Ursini) are independent of the chosen weight, which is known to be false for groups but turns out to be true in any two-nilpotent semi-abelian category.Comment: 13 page

A decomposition formula for the weighted commutator

We decompose the weighted subobject commutator of M. Gran, G. Janelidze and A. Ursini as a join of a binary and a ternary commutator.Comment: 7 pages. Dedicated to George Janelidze on the occasion of his sixtieth birthda

Australian Residential Solar Feed-in Tariffs: Industry Stimulus or Regressive Form of Taxation?

Feed-in Tariffs (FiT) for residential photovoltaic solar technologies are available in most Australian jurisdictions. Financial incentives under FiT are in addition to those provided by the Small-Scale Renewable Energy Scheme which forms part of the national 20% Renewable Energy Target. Little attention has been paid to the welfare impacts of FiT on retail electricity prices and social policy objectives. Our analysis indicates that current FiT are a regressive form of taxation. By providing estimates of household impact by income groupings, we conclude that wealthier households are beneficiaries and the effective taxation rate for low income households is three times higher than that paid by the wealthiest households.Feed-in Tariffs, Electricity Prices

Australia's energy options: policy choice not economic inevitability

Executive summary A reliable and affordable supply of energy is a fundamental component to a vibrant economy. As a major source of commodities, including significant known reserves of low carbon emission energy sources, Australia is well positioned to supply the world’s future energy needs. In order for that to occur, Australia needs to examine all its energy options. The Government released a Draft Energy White paper in November 2011. CEDA considers this an opportunity that the Government should not miss in ensuring that Australia not only develops its energy resources for national economic gain but also to guarantee access to reasonably priced energy for Australian consumers. CEDA determined it would contribute to this significant debate by undertaking a year-long research project that examined Australia’s future energy options. As part of this research project CEDA published three policy perspectives that addressed Australia’s nuclear, renewables and efficiency and unconventional energy options. Recommendations in each of these perspectives were made with the specific aim of providing policy-makers with evidence-based research on the various energy sources either currently available or being actively explored and researched, often funded through the public purse. Fundamental governance decisions underpinned by strong economic policy arguments were at the centre of these recommendations. This final research report canvasses one of the more significant current debates associated with the availability of energy – the Australian electricity market. It puts forward a series of recommendations designed to enhance this element of the energy sector’s efficiency, security and effectiveness by placing consumers at the centre of the energy market and a reform agenda is proposed. Related identifier: ISBN 0 85801 284

An observation on n-permutability

We prove that in a regular category all reflexive and transitive relations are symmetric if and only if every internal category is an internal groupoid. In particular, these conditions hold when the category is n-permutable for some n.Comment: 6 page

Knowledge-based systems and NASA's software support environment

A proposed role for knowledge-based systems within NASA's Software Support Environment (SSE) is described. The SSE is chartered to support all software development for the Space Station Freedom Program (SSFP). This includes support for development of knowledge-based systems and the integration of these systems with conventional software systems. In addition to the support of development of knowledge-based systems, various software development functions provided by the SSE will utilize knowledge-based systems technology

Can chaos be observed in quantum gravity?

Full general relativity is almost certainly 'chaotic'. We argue that this entails a notion of nonintegrability: a generic general relativistic model, at least when coupled to cosmologically interesting matter, likely possesses neither differentiable Dirac observables nor a reduced phase space. It follows that the standard notion of observable has to be extended to include non-differentiable or even discontinuous generalized observables. These cannot carry Poisson-algebraic structures and do not admit a standard quantization; one thus faces a quantum representation problem of gravitational observables. This has deep consequences for a quantum theory of gravity, which we investigate in a simple model for a system with Hamiltonian constraint that fails to be completely integrable. We show that basing the quantization on standard topology precludes a semiclassical limit and can even prohibit any solutions to the quantum constraints. Our proposed solution to this problem is to refine topology such that a complete set of Dirac observables becomes continuous. In the toy model, it turns out that a refinement to a polymer-type topology, as e.g. used in loop gravity, is sufficient. Basing quantization of the toy model on this finer topology, we find a complete set of quantum Dirac observables and a suitable semiclassical limit. This strategy is applicable to realistic candidate theories of quantum gravity and thereby suggests a solution to a long-standing problem which implies ramifications for the very concept of quantization. Our work reveals a qualitatively novel facet of chaos in physics and opens up a new avenue of research on chaos in gravity which hints at deep insights into the structure of quantum gravity.Comment: 6 pages + references -- matches published version (clarifications added for why GR with cosmologically interesting matter likely fails our notion of weak-integrability