User-defined data types and operators in occam

This paper describes the addition of user-defined monadic and dyadic operators to occam* [1], together with some libraries that demonstrate their use. It also discusses some techniques used in their implementation in KRoC [2] for a variety of target machines

Higher levels of process synchronisation

Four new synchronisation primitives (SEMAPHOREs, RESOURCEs, EVENTs and BUCKETs) were introduced in the KRoC 0.8beta release of occam for SPARC (SunOS/Solaris) and Alpha (OSF/1) UNIX workstations [1][2][3]. This paper reports on the rationale, application and implementation of two of these (SEMAPHOREs and EVENTs). Details on the other two may be found on the web [4]. The new primitives are designed to support higher-level mechanisms of SHARING between parallel processes and give us greater powers of expression. They will also let greater levels of concurrency be safely exploited from future parallel architectures, such as those providing (virtual) shared-memory. They demonstrate that occam is neutral in any debate between the merits of message-passing versus shared-memory parallelism, enabling applications to take advantage of whichever paradigm (or mixture of paradigms) is the most appropriate. The new primitives could be (but are not) implemented in terms of traditional channels, but only at the expense of increased complexity and computational overhead. The primitives are immediately useful even for uni-processors - for example, the cost of a fair ALT can be reduced from O(n) to O(1). In fact, all the operations associated with new primitives have constant space and time complexities; and the constants are very low. The KRoC release provides an Abstract Data Type interface to the primitives. However, direct use of such mechanisms still allows the user to misuse them. They must be used in the ways prescribed (in this paper and in [4]) else their semantics become unpredictable. No tool is provided to check correct usage at this level. The intention is to bind those primitives found to be useful into higher level versions of occam. Some of the primitives (e.g. SEMAPHOREs) may never themselves be made visible in the language, but may be used to implement bindings of higher-level paradigms (such as SHARED channels and BLACKBOARDs). The compiler will perform the relevant usage checking on all new language bindings, closing the security loopholes opened by raw use of the primitives. The paper closes by relating this work with the notions of virtual transputers, microcoded schedulers, object orientation and Java threads

The deconstruction of time

Derrida's claim that there can be no concept of time that escapes from the sphere of the metaphysical presents us with three major questions: (1) Why does Derrida make this claim? What does he mean by it? (2) How, in the light of this claim ought we to read Husserl and Heidegger who aimed at just what Derrida rules out? (3) How can we square the claim with other things Derrida says about time and about metaphysics? We undertake a critical reading of the two major works on time by Husserl and Heidegger respectively, arguing that while each of these two texts does indeed subscribe to such metaphysical values as fundamentality, certainty, unity, identity and wholeness, they nonetheless make a substantial contribution to our release from the domination of 'the ordinary concept of time'. Furthermore, we argue, Derrida's own writing is marked by the same (perhaps inevitable) 'metaphysical' shadow, albeit in an exemplary self-conscious manner. To Derrida's claim about the impossibility of a non-metaphysical concept of time we reply (a) he elsewhere endorses a 'pluri-dimensional' temporality, and (b) when being careful, he admits that it is not concepts per se that are metaphysical, but their mode of textual articulation. From these two concessions our double strategy develops. I. His denial of an original, primitive time, coupled with his understanding of metaphysics in terms of textual articulation licences a programme for the description of temporal structures and representations of time, one abjuring any foundationalist pretensions, and resisting the temptation to spatializing interpretations. II. We redescribe the 'moment' in a way that breaks utterly with any representational element whatever. This approximates in temporal terms the time-dissolving moves found both in the latter Heidegger, and also in Derrida

Atomic Analogy of Poverty

An analogy between the model of an atom and poverty of an individual in a poverty field is presented to construe that poverty levels are quantized in similar notions as in the models of an atom. This analogy provides a rational explanation of the observed phenomena in society in part as well as it can be used to predict future observations. Concepts proposed in this paper may lead to a framework to quantify poverty, absolute or relative, and suggest enhanced collaboration between moral science and natural science to study poverty dynamic

Funding Public Education Based on the Concept of Cost of Living

The vast majority of education finance researchers would concede that cost of living issues are legitimate variables for any education finance distribution program

Editor\u27s Foreword

This issue, as well as the previous issue, of Educational Considerations is devoted to the concept of financing public elementary and secondary education in the United States

Educational Considerations, vol. 25 (2) Full Issue

Educational Considerations, vol. 25 (2) Spring 1998 - Full issu

Guest Editors\u27 Foreword

This issue, as well as the next, is devoted to the financing of public elementary and secondary schools in America