A categorical analogue of the monoid semiring construction

This paper introduces and studies a categorical analogue of the familiar monoid semiring construction. By introducing an axiomatisation of summation that unifies notions of summation from algebraic program semantics with various notions of summation from the theory of analysis, we demonstrate that the monoid semiring construction generalises to cases where both the monoid and the semiring are categories. This construction has many interesting and natural categorical properties, and natural computational interpretations.Comment: 34 pages, 5 diagram

Types and forgetfulness in categorical linguistics and quantum mechanics

The role of types in categorical models of meaning is investigated. A general scheme for how typed models of meaning may be used to compare sentences, regardless of their grammatical structure is described, and a toy example is used as an illustration. Taking as a starting point the question of whether the evaluation of such a type system 'loses information', we consider the parametrized typing associated with connectives from this viewpoint. The answer to this question implies that, within full categorical models of meaning, the objects associated with types must exhibit a simple but subtle categorical property known as self-similarity. We investigate the category theory behind this, with explicit reference to typed systems, and their monoidal closed structure. We then demonstrate close connections between such self-similar structures and dagger Frobenius algebras. In particular, we demonstrate that the categorical structures implied by the polymorphically typed connectives give rise to a (lax unitless) form of the special forms of Frobenius algebras known as classical structures, used heavily in abstract categorical approaches to quantum mechanics.Comment: 37 pages, 4 figure

Coherence and strictification for self-similarity

This paper studies questions of coherence and strictification related to self-similarity - the identity $S\cong S\otimes S$ in a (semi-)monoidal category. Based on Saavedra's theory of units, we first demonstrate that strict self-similarity cannot simultaneously occur with strict associativity -- i.e. no monoid may have a strictly associative (semi-)monoidal tensor, although many monoids have a semi-monoidal tensor associative up to isomorphism. We then give a simple coherence result for the arrows exhibiting self-similarity and use this to describe a `strictification procedure' that gives a semi-monoidal equivalence of categories relating strict and non-strict self-similarity, and hence monoid analogues of many categorical properties. Using this, we characterise a large class of diagrams (built from the canonical isomorphisms for the relevant tensors, together with the isomorphisms exhibiting the self-similarity) that are guaranteed to commute.Comment: Significant revisions from previous version: proofs simplified and based on Saavedra units & idempotent splitting, monoidal equivalences made explicit, expository sections significantly revised and shortened, notation and terminology revised and clarified, a clearer criterion for coherence give

Detailed comparative analysis of PESQ and VISQOL behaviour in the context of playout delay adjustments introduced by VOIP jitter buffer algorithms

The default best-effort Internet presents significant challenges for delay-sensitive applications such as VoIP. To cope with non determinism, receiver playout strategies are utilised in VoIP applications that adapt to network condition. Such strategies can be divided into two different groups, namely per-talkspurt and per-packet. The former make use of silence periods within natural speech and adapt such silences to track network conditions, thus preserving the integrity of active speech talkspurts. Examples of this approach are described in [1, 2]. Per packet strategies are different in that adjustments are made both during silence periods and during talkspurts by time-scaling of packets, a technique also known in the literature as time-warping. This approach is more effective in coping with short network delay changes because the per talkspurt approach can only adapt during recognized silences even though the duration of many delay spikes may be less than that of a talkspurt. This approach however introduces potential degradation caused by the scaling of speech packets. Examples of this approach are described in [3, 4] and such techniques are frequently deployed in popular VoIP applications such as GoogleTalk and Skype. In this research, we focus on applications that deploy per talkspurt strategies, which are commonly found in current telecommunication networks

Detailed comparative analysis of PESQ and VISQOL behaviour in the context of playout delay adjustments introduced by VOIP jitter buffer algorithms

The default best-effort Internet presents significant challenges for delay-sensitive applications such as VoIP. To cope with non determinism, receiver playout strategies are utilised in VoIP applications that adapt to network condition. Such strategies can be divided into two different groups, namely per-talkspurt and per-packet. The former make use of silence periods within natural speech and adapt such silences to track network conditions, thus preserving the integrity of active speech talkspurts. Examples of this approach are described in [1, 2]. Per packet strategies are different in that adjustments are made both during silence periods and during talkspurts by time-scaling of packets, a technique also known in the literature as time-warping. This approach is more effective in coping with short network delay changes because the per talkspurt approach can only adapt during recognized silences even though the duration of many delay spikes may be less than that of a talkspurt. This approach however introduces potential degradation caused by the scaling of speech packets. Examples of this approach are described in [3, 4] and such techniques are frequently deployed in popular VoIP applications such as GoogleTalk and Skype. In this research, we focus on applications that deploy per talkspurt strategies, which are commonly found in current telecommunication networks

Identifying the Implications of most Warming Foods: A Pilot Analysis

The new found popular interest in sustainable development is highly skewed towards areas that are politically visible, such as transport and in particular the evils of air travel. This situation is mirrored in the academic community with an explosion of articles on sustainable transport (an EBSCO web search yielded 552 academic references to Sustainable Transport while for example Sustainable Livestock only found less than 10% of that number1). Nonetheless, only 14% of GHG’s actually result from transport, with as little as 2% coming from aviation, against 32% resulting from agriculture and land use – a major part of which can be directly attributed to the food chain (Stern, 2006). Moreover within the food system, certain areas such as livestock production are particularly problematic with meat and dairy products contributing more than 50% of the total GHG’s emitted (Kramer et al, 1999). Another recent study in the UK shows that GHG emissions attributable to meat and dairy consumption are about 4 times more than the GHG emissions generated from fruit and vegetable consumption (Garnett, 2007).Agribusiness, Agricultural and Food Policy, Farm Management, Food Consumption/Nutrition/Food Safety, Industrial Organization,

Wider applications for Lean: an examination of the fundamental principles within public sector organisations

Purpose – The lean enterprise model has been adopted in a wide range of industries beyond its origins in the motor industry. To achieve this there has been a considerable extension of the lean concept outside high-volume repetitive manufacture. The purpose of this paper is to present an in-depth study of the application of lean within the British Royal Air Force. It offers a number of new insights which have implications for the future development and adoption of lean in service contexts, and the public sector in particular. Design/methodology/approach – To illustrate the issues of application of lean outside automotive, this paper considers the adoption of the lean concept by the Tornado joint integrated project team within the UK Ministry of Defence. A review of methods of application of lean used within Tornado are studied. The paper considers how the fundamental principles of lean apply in this environment and how, considering these principles, methods of implementation should be modified. Findings – This paper finds that the five lean fundamental principles apply in Tornado but they need to considered specifically within the public service context particularly the pull principle. Hence the authors offer three propositions relating to the use of the lean principles of value, waste, flow and pull in the public sector, and one for perfection only relating to military organisations. Originality/value – This paper makes an important contribution by demonstrating that lean can be successfully applied, in a public service context, with only modest modifications to its core principles, principally about how customer demand (pull) is managed. The implication of this finding demonstrates that to be adopted successfully, lean must be adapted to its context and the lean principles need to be reviewed too

International Capital Taxation.

Globalization carries profound implications for tax systems, yet most tax systems, including that of the UK, still retain many features more suited to closed economies. The purpose of this chapter is to assess how tax policy should reflect the changing international economic environment. Institutional barriers to the movement of goods, services, capital, and (to a lesser extent) labour have fallen dramatically since the Meade Report (Meade, 1978) was published. So have the costs of moving both real activity and taxable profits between tax jurisdictions. These changes mean that capital and taxable profits in particular are more mobile between jurisdictions than they used to be. Our focus is on the taxation of capital and our main conclusions may be summarized as follows