Operational causes of bankruptcy propagation in supply chain

With the increasing interdependence among supply chain members, bankruptcy of a supply chain member may be caused by operational decisions of other members. To investigate how bankruptcy occurs and propagates in supply chain networks, we build a multi-agent simulation model for a two-stage supply chain that consists of multiple upstream manufacturers and multiple downstream retailers. Based on the developed simulation model, we study impacts of various operational parameters and decisions, such as horizontal competition among retailers, order allocation strategies of retailers, wholesale price of manufacturers, characteristics of market demand and number of retailers, on bankruptcy propagation. Since many operational decisions of a firm are made under financial constraints, we also investigate the linkage between firm's operational risks and financial decisions (e.g., the maximal risk of cash flow that a member is willing to take, and the up-front payment proportion of retailers in a two-period payment policy). Experimental results reveal that operational interactions between supply chain members and operational decisions made by supply chain members are important causes of bankruptcy propagation, but impacts of these operational parameters and decisions depend on financial decisions. These observations indicate that supply chain members can moderately hedge their operational risk through financial decisions.     

Grammar semantics, analysis and parsing by abstract interpretation

We study abstract interpretations of a fixpoint protoderivation semantics defining the maximal derivations of a transitional semantics of context-free grammars akin to pushdown automata. The result is a hierarchy of bottom-up or top-down semantics refining the classical equational and derivational language semantics and including Knuth grammar problems, classical grammar flow analysis algorithms and parsing algorithms.     

A novel formalization of symbolic trajectory evaluation semantics in Isabelle/HOL

This paper presents a formal symbolic trajectory evaluation (STE) theory based on a structural netlist circuit model, instead of an abstract next state function. We introduce an inductive definition for netlists, which gives an accurate and formal definition for netlist structures. A closure state function of netlists is formally introduced in terms of the formal netlist model. We refine the definition of the defining trajectory and the STE implementation to deal with the closure state function. The close correspondence between netlist structures and properties is discussed. We present a set of novel algebraic laws to characterize the relation between the structures and properties of netlists. Finally, the application of the new laws is demonstrated by parameterized verification of the properties of content-addressable memories.     

LMOD：一种基于本体描述的电子学习资源库模型*

随着电子学习系统应用的深入,资源库已经成为影响电子学习系统可用性的一个重要因素。针对现有资源库在资源检索查全率、查准率上存在的不足,将语义特征引入到电子学习资源库模型的构建之中,提出了一种基于本体描述的电子学习资源库模型LMOD。LMOD通过构建电子学习资源库本体并生成相应的语义元数据规范地描述资源,将资源以机器可以理解的方式组织起来;并利用语义学视图规范用户查询语句。在此基础上实现基于语义的资源查询,以有效地解决搜索中含糊解释与同义识别的问题。该模型能够有效克服现有资源库建设方案的缺点,提升资源库的使用效率与可用性。     

Modeling Content for Semantic-Level Querying of Multimedia

Many semantic content-based models have been developed for modeling video and audio in order to enable information retrieval based on semantic content. The level of querying of the media depends upon the semantic aspects modeled. This paper proposes a semantic content-based model for semantic-level querying that makes full use of the explicit media structure, objects, spatial relationships between objects, events and actions involving objects, temporal relationships between events and actions, and integration between syntactic and semantic information.     

Functional Differentiation of Computer Programs

We present a purely functional implementation of the computational differentiation tools—the well known numeric (i.e., not symbolic) techniques which permit one to compute point-wise derivatives of functions defined by computer programs economically and exactly (with machine precision). We show how the use of lazy evaluation permits a transparent and elegant construction of the entire infinite tower of derivatives of higher order for any expressions present in the program. The formalism may be useful in various problems of scientific computing which often demand a hard and ungracious human preprocessing before writing the final code. Some concrete examples are given.     

ADL: An Activity Description Language for Real-Time Networks

This paper introduces and motivates ADL, a new formal notation for the specification of the temporal and functional behaviour of concurrent processes. ADL is tailored to be directly compatible with the DORIS design method. It combines a graphical Activity State-Machine (ASM) notation and a model-based Activity Functional Behaviour (AFB) notation. The abstract syntax, and static and dynamic semantics for the ASM notation are given, the dynamic semantics being given proof-theoretically in many-sorted logic extended with the RTL ‘occurrence’ relation, Θ, and the ERTL ‘holding’ relation, Φ. ADL is used to specify a small network, and proofs are given of its timeliness and safety properties. Received November 1998 / Accepted in revised form May 2000     

Ordered Semantic Hyper-Linking

The ordered semantic hyper-linking strategy is complete for first-order logic and accepts a user-specified natural semantics that guides the search for a proof. Any semantics in which the meanings of the function and predicate symbols are computable on ground terms may be used. This instance-based strategy is efficient on near-propositional problems, is goal sensitive, and has an extension to equality and term rewriting. However, it sometimes has difficulty generating large terms. We compare this strategy with some others that use semantic information, and present a proof of soundness and completeness. We also give some theoretical results about the search efficiency of the strategy. Some examples illustrate the performance of the strategy.