Top-down design in the context of parallel programs

A class of parallel programs, based on Free Choice Petri nets, is modeled by associating operators and predicates with vertices of the net. The model, called a formal parallel program (FPP), forms a natural extension of flow-chart notation to parallel programs. Definitions are made of the behaviour of an FPP, and the simulation of one FPP by another. A class of top-down FPPs is next defined, by requiring program graphs to be obtained through successive refinement steps, using a restricted set of control structures. Using the above definitions, it is shown that there exists an FPP ℰ satisfying the property that for any top-down FPP ℰ′ simulating ℰ, the degree of parallelism attainable in ℰ′ is smaller than that in ℰ. The measure of parallelism used is the number of different ways of carrying out a computation. In the case of parallel programs, this phenomenon of loss of parallelism therefore uncovers a performance factor which may offset some of the advantages of using top-down design

On the interconnection structure of cellular networks

This paper presents a model which can be used to represent many of the interconnection patterns commonly found in cellular networks. This model is then used to classify cellular networks according to the degree of regularity in their interconnection patterns. Specifically, three classes of cellular networks, corresponding to three forms of interconnection regularity, are defined. A concept of network realization is then developed to detect structural similarities in different networks and is used to compare the computational capabilities of these three classes

Tractable Bayesian inference for an unidentified simple linear regression model

In this paper, I propose a tractable approach to Bayesian inference in a simple linear regression model for which the standard exogeneity assumption does not hold. By specifying a beta prior for the squared correlation between an error term and regressor, I demonstrate that the implied prior for a bias parameter is t-distributed. If the posterior distribution for the identified regression coefficient is normal, this implies that the posterior distribution for the unidentified treatment effect is the convolution of a normal distribution and a t-distribution. This result is closely related to the literatures on unidentified regression models, imperfect instrumental variables, and sensitivity analysis

How to Pay for the Coronavirus Emergency The Fiscal Challenge

The coronavirus emergency presents the British Government with the greatest fiscal challenge since the Second World War. While the course of the emergency will be determined by the nature of the infection and the arrangements for dealing with it, the course of the recovery from the epidemic will be determined by the financing of the emergency, whether this is done by the government, or left to households and firms running up private debt. The quickest recovery will be obtained by maintaining a high level of government borrowing serviced by taxes on wealth and profits. This would reverse some of the regressive features of the epidemic which is exacerbating an unequal distribution of income and wealth

The impact of Covid-19 restrictions on economic activity: evidence from the Italian regional system

Non-pharmaceutical interventions adopted by governments to halt the spread of Sars-Cov2 are thought to have non-trivial consequences for the economy. The purpose of this paper is to estimate the economic impact of non-pharmaceutical interventions in Italy, by taking advantage of timing differences in their implementation across regions and employing mobility data to proxy activity. To achieve this, we estimate one-way and two-way fixed effects models on a large sample of Italian provinces. We also isolate a set of well-defined quasi-natural experiments in which one region goes from a lower to a higher tier of restrictions, while a neighbouring region remains in the lower tier, for which we can estimate difference-in-differences and continuous treatment models. Moreover, in order to observe whether the impact of restrictions has changed over time, we split the sample around December 2020 and replicate the analysis in each subsample. Our case studies indicate that an Italian province moving from tier 2 to tier 3 in the system of restrictions can expect a fall in mobility of between 12 and 18 percentage points. Thus, we provide evidence of the negative effects of non-pharmaceutical interventions on economic activity. Finally, we provide some evidence that the effectiveness of NPIs in reducing mobility is likely to reduce over time, which has important policy implications. Our estimations are robust to a number of checks

Do research universities recession proof their regions? Evidence from state flagship college towns

No abstract available

A shorter working week as part of a green caring economy: feminist green new deal policy paper

In this report, we argue that a shorter working week, as part of a wider set of policy changes, can promote gender-equal distributions in paid work, unpaid work, and income, while facilitating a green transition. The paper analyses time-use data and evidence on the impact of Covid-19 on working patterns together with international case studies and makes a series of policy recommendations. We explore what other mechanisms are needed in order to ensure that a shorter working week and a green transition are equitable. Policy experiments in shorter working hours are ongoing, with trials for a four-day week currently being designed in Spain and Scotland, and employer trials beginning here in the UK. A shorter working week, in combination with an expansion in public social infrastructure and universal basic services, is an important measure to address the social and political consequences of dysfunctional health and social care systems, extreme inequality, and environmental breakdown

A history of aggregate demand and supply shocks for the United Kingdom, 1900 to 2016

While economic theory has been applied to numerous topics in economic history, there are very few attempts to interpret major macroeconomic shocks from the perspective of standard Keynesian theory. This paper presents a history of aggregate demand and supply shocks spanning 1900 – 2016 for the United Kingdom, whose signs are identified using economic theory. We utilise sign restrictions derived from an AD-AS framework consistent with the workhorse New Keynesian model, and demonstrate how they can be used to identify the signs of structural shocks. The existence of 33 large shocks is inferred from estimated vector autoregressions, comprising 21 demand shocks and 12 supply shocks. We find that aggregate supply shocks were important in the late 1920s and early 1970s, which we attribute to changes in the bargaining power of labour. We also identify positive aggregate demand shocks in the mid-1970s, which we attribute to fiscal policy and suggest that these shocks will have exacerbated the inflationary effects of the 1973 oil price crisis, while mitigating its unemployment effects