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161.
The exploratory nature of a scientific computational experiment involves executing variations of the same workflow with different approaches, programs, and parameters. However, current approaches do not systematize the derivation process from the experiment definition to the concrete workflows and do not track the experiment provenance down to the workflow executions. Therefore, the composition, execution, and analysis for the entire experiment become a complex task. To address this issue, we propose the Algebraic Experiment Line (AEL). AEL uses a data-centric workflow algebra, which enriches the experiment representation by introducing a uniform data model and its corresponding operators. This representation and the AEL provenance model map concepts from the workflow execution data to the AEL derived workflows with their corresponding experiment abstract definitions. We show how AEL has improved the understanding of a real experiment in the bioinformatics area. By combining provenance data from the experiment and its corresponding executions, AEL provenance queries navigate from experiment concepts defined at high abstraction level to derived workflows and their execution data. It also shows a direct way of querying results from different trials involving activity variations and optionalities, only present at the experiment level of abstraction. 相似文献
162.
程序流程图在整个软件工程的生命周期中发挥着非常重要的作用。在软件设计中,设计人员通常需要先根据算法从结构上画出程序执行流程图,然后再依据流程图写出相应的源程序代码;在分析和维护软件时,如果能先将源程序代码逆向转换成流程图,则可以有效地帮助分析程序结构。显然,若能让计算机自动地实现流程图与源程序代码之间的相互转换,将大量节省软件开发的人力资源和时间耗费。讨论了如何利用基于边的图文法EGG来自动地实现这种转换,并用具体例子展示了应用EGG图文法的归约和推导操作分别实现流程图的语法分析和流程图的逆向生成,前者可以完成从流程图自动生成源程序代码,而后者则可以从源程序代码自动生成流程图。 相似文献
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166.
In this series of papers we set out to generalize the notion of classical analytic deduction (i.e., deduction via elimination rules) by combining the methodology of labelled deductive systems (LDS) with the classical systemKE. LDS is a unifying framework for the study of logics and of their interactions. In the LDS approach the basic units of logical derivation are not just formulae butlabelled formulae, where the labels belong to a given labelling algebra. The derivation rules act on the labels as well as on the formulae, according to certain fixed rules of propagation. By virtue of the extra power of the labelling algebras, standard (classical or intuitionistic) proof systems can be extended to cover a much wider territory without modifying their structure. The systemKE is a new tree method for classical analytic deduction based on analytic cut.KE is a refutation system, like analytic tableaux and resolution, but it is essentially more efficient than tableaux and, unlike resolution, does not require any reduction to normal form.We start our investigation with the family of substructural logics. These are logical systems (such as Lambek's calculus, Anderson and Belnap's relevance logic, and Girard's linear logic) which arise from disallowing some or all of the usual structural properties of the notion of logical consequence. This extension of traditional logic yields a subtle analysis of the logical operators which is more in tune with the needs of applications. In this paper we generalize the classicalKE system via the LDS methodology to provide a uniform refutation system for the family of substructural logics.The main features of this generalized method are the following: (a) each logic in the family is associated with a labelling algebra; (b) the tree-expansion rules (for labelled formulae) are the same for all the logics in the family; (c) the difference between one logic and the other is captured by the conditions under which a branch is declared closed; (d) such conditions depend only on the labelling algebra associated with each logic; and (e) classical and intuitionistic negations are characterized uniformly, by means of the same tree-expansion rules, and their difference is reduced to a difference in the labelling algebra used in closing a branch. In this first part we lay the theoretical foundations of our method. In the second part we shall continue our investigation of substructural logics and discuss the algorithmic aspects of our approach. 相似文献
167.
Mechanisms different from the well-known DOL-systems are proposed for construction of cube-free words. A generator is presented,
which is described by logical programming means and models the process of derivation in arbitrary grammars.
Translated from Kibernetika i Sistemnyi Analiz, No. 6, pp. 18–25, November–December, 1999. 相似文献
168.
169.
《国际计算机数学杂志》2012,89(3-4):197-205
L homomorphisms, i.e. structure preserving mappings between OL systems, are introduced. Every L homomorphism is determined in a unique way by a homomorphism between thefree monoids generated by the alphabets of the related systems and by a nonnegative integer. Thereby the notion of L homomorphism is characterized in a decidable way. L homomorphisms are related to all essential notions of L systems like derivations, adult languages, local catenativity, and ranks of DOL systems. Using the notion of L homomorphism a letter merging procedure for the reduction of OL systems is developed which is similar to the state merging algorithm for the reduction of finite state machines. 相似文献
170.
This paper investigates the noise sources in a single-ended class D amplifier (SECDA) and suggests corresponding ways to lower the noise. The total output noise could be expressed as a function of the gain and noises from different sources. According to the function, the bias voltage (VB) is a primary noise source, especially for a SECDA with a large gain. A low noise SECDA is obtained by integrating a filter into the SECDA to lower the noise of the VB. The filter utilizes an active resister and an 80 pF capacitance to get a 3 Hz pole. A noise test and fast Fourier transform analysis show that the noise performance of this SECDA is the same as that of a SECDA with an external filter. 相似文献