An implementation of Deflate in Coq

The widely-used compression format "Deflate" is defined in RFC 1951 and is based on prefix-free codings and backreferences. There are unclear points about the way these codings are specified, and several sources for confusion in the standard. We tried to fix this problem by giving a rigorous mathematical specification, which we formalized in Coq. We produced a verified implementation in Coq which achieves competitive performance on inputs of several megabytes. In this paper we present the several parts of our implementation: a fully verified implementation of canonical prefix-free codings, which can be used in other compression formats as well, and an elegant formalism for specifying sophisticated formats, which we used to implement both a compression and decompression algorithm in Coq which we formally prove inverse to each other -- the first time this has been achieved to our knowledge. The compatibility to other Deflate implementations can be shown empirically. We furthermore discuss some of the difficulties, specifically regarding memory and runtime requirements, and our approaches to overcome them

The burden of ‘white’ sugar: Producing and consuming whiteness in Australia

This article investigates the history of the Queensland cane sugar industry and its cultural and political relations. It explores the way the sugar industry was transformed from an enterprise drawing on the traditional plantation crop cultivated by an unfree labour force and employing workers into an industry that was an important, symbolical element of ‘White Australia’ that was firmly grounded in the cultural, political, nationalist, and racist reasoning of the day. The demographic and social changes drew their incitement and legitimation from the ‘White Australia’ culture that was represented in all social strata. Australia was geographically remote but culturally close to the mother country and was assigned a special position as a lone outpost of Western culture. This was aggravated by scenarios of allegedly imminent invasions by the surrounding Asian powers, which further urged cane sugar’s transformation from a ‘black’ to a ‘white man’s industry’. As a result, during the sugar strikes of the early 20th century, the white Australian sugar workers were able to emphasize their ‘whiteness’ to press for improvements in wages and working conditions. Despite being a matter of constant discussion, the public acceptance of the ‘white sugar campaign’ was reflected by the high consumption of sugar. Moreover, the industry was lauded for its global uniqueness and its significance to the Australian nation. Eventually, the ‘burden’ of ‘white sugar’ was a monetary, but even more so moral support of an industry that was supposed to provide a solution to population politics, support the national defence, and symbolize the technological advancement and durability of the ‘white race’ in a time of crisis

Energy Expenditure of Structural Firefighters During a Typical Work Shift

This study examined the energy expenditure and heart rate of structural firefighters. Subjects included nine (N=9) full-time firefighters from Ithaca, NY, ranging in age from 21-48 years. All subjects completed four test days. Test day 1 included measurement of VO2max and anthropometric data. During test days 2-4, activity count to estimate energy expenditure (EE) and heart rate (HR) were measured simultaneously using an Actiheart Monitor. During each shift (test days 2-4), subjects were required to document all activity at 15 minute increments. Activities were subsequently classified as emergency response (ER), simulation training (ST) or other shift activities (SA), and were synchronized with the activity count and heart rate data from the Actiheart. A 3x2 repeated measures ANOVA compared heart rate and activity count between ER and SA during the three test days. Data during ST was captured on only one firefighter therefore ST data was not included in the statistical analysis due to small sample size. As expected, mean HR was significantly higher during ER compared to SA. Surprisingly, EE during SA was significantly higher than EE during ER. The large difference could be due to the variety and intensity of tasks completed during SA and the amount of time during those activities. Accurate exercise prescription is essential to meet the physiological demands of the profession. Physical demands affect job performance and ultimately public safety. Shift activities like truck checks and truck washing should be considered when prescribing exercise to this population