Since Vendler classified aspect into four categories, state, achievement, activity, and accomplishment, much effort has been made to define the notion of aspect logically. It is commonly agreed that aspect represents the general temporal characteristics of events and states. However, there still remains a considerable amount of disagreement about its formal treatment. One of the major problems is that the aspect of a sentence shifts by certain types of sentence construction. For instance, adding time adverbials to a sentence modifies the original aspect, taking the progressive form of the verb changes the aspect, and so on. These phenomena are known as the aspect shifts. The other is the problem known as the imperfective paradox. The imperfective paradox is a problem of the truth definition of the progressives. The truth condition of the progressive form of the sentence is defined at an internal subinterval of the temporal range of the corresponding non-progressive sentence. If the truth condition of the progressive form of the sentence is defined using the truth condition of the non-progressive form of the sentence, there are logical contradictions of truth definition in a sentence such as "Max was building a house, but he never built it". These problems cause much confusion (1) in the truth definition of aspects, (2) in the definition of aspect operations, such as initiative, terminative, progressive, perfective, etc., and also (3) in the definition of adding time adverbials. This paper reviews the semantic problems with respect to aspect, and presents a consistent mechanism of aspect interpretation in order to settle all these semantic puzzles at once. For the sake of logical clarity, we construct a formal language, Lt, where every meaningful formula is a pair of a meaningful sentence and its aspect. The syntax of Lt describes the phenomenology of aspect shifts. The semantics of Lt defines temporal interpretation for all the meaningful sentences of Lt, with assuming the temporal interpretations of three inherent aspects, state, achievement, and activity. The proposed aspect interpretation gives a reasonable account for aspect shifts, and solves the imperfective paradox by asssuming the time structure to be backwards linear.

This paper investigates the compositionality of operational models for concurrency induced by labeled transition systems (LTS's). These models are defined on the basis of a metric domain first introduced by de Bakker and Zucker; the domain is a complete metric space consisting of tree-like structures called processes. Transition system specifications (TSS's) define LTS's; the set of states of such a LTS A is the set of terms generated by a signature Σ. For the syntactical operators F contained in Σ, semantic operations (on processes) associated with F are derived from the TSS S by which A is defined, provided that S satisfies certain syntactical restrictions. By means of these operations, the compositionality of the operational model induced by A is established. A similar result was obtained by Rutten from TTS's which define finitely branching LTS's. The main contribution of this paper is generalization of Rutten's result to be applicable to TSS's which are based on applicative languages including recursion, parameterized statements, and value passing, and which define infinitely branching LTS's. A version of typed λ-calculus incorporating µ-notation is employed as a formalism for treating recursion, parameterized statements, and value-passing. Infinitely branching LTS's are needed to treat programming languages including value passing such as CCS.

An automatic optimization system for semiconductor devices has been built-up by fully interfacing an optimizer and a device-analysis code supplemented with sensitivity analysis. The device-analysis code is thought of as a part of a pipeline of simulators. The latters are regarded as subprocesses by the optimizer, which controls their I/O stream. The action of the pipeline is iterated until the optimum set of design parameters is determined. An important feature of the system is that all the derivatives required in the sensitivity analysis are calculated analytically, this providing a substantial improvement in both the numerical accuracy and computational efficiency, and making the scheme attractive from the application standpoint. A few examples of optimization of MOS devices are shown and the performance is reported, indicating that a system of this kind can usefully be exploited in a design environment.

We describe two information disseminating schemes, t-disseminate and t-Rdisseminate in a computer network with N processors, where each processor can send a message to t-directions at each round. If no processors have failed, these schemes are time optimal. When at most t processors have failed, for t1 and t2 any of these schemes can broadcast information within any consecutive logt+1N2 rounds, and for an arbitrary t they can broadcast information within any consecutive logt+1N3 rounds.

The semantics of a language for communicating processes is investigated, and three full abstractness results for are established. The language contains atomic actions, termination, inaction, sequential composition, alternative composition, parallel composition, action restriction, and a form of guarded recursion. (The guardedness restriction on recursion is needed to establish one of the full abstractness results.) Three Plotkin-style operational semantics WL, CWL, and IWL of the language are defined. These semantics are linear in that the meaning of each program in any of these semantics is a set of action sequences the program may perform, and are weak in that the action sequences are obtained by ignoring (finte sequences of) internal moves. All the three semantics distinguish divergence (an infinite sequence of internal moves) from deadlock. The semantics IWL differs from the other two in that IWL is a so-called interal action semantics taking into account only internal moves under the assumption that the environment allows no (external) communication actions, and hence, the only possible actions for processes are internal moves, whereas the other two semantics take into account communication actions in addition to internal moves. The two semantics WL and CWL differ each other in that CWL is a so- called completed trace semantics, whereas WL is not. Then, two compositional models RF and IRF for the language are proposed, and the full a bstractness of RF (resp. of IRF) w. r. t. WL and CWL (resp. w. r. t. IWL), as expressed in the following, is established:s1s2(*) S[][S[]is a context of ⇒S[s1]S[s2]],where ,RF,WL, RF,CWL, IRF,IWL. A similar full abstractness result has been established by Bergstra, Klop, and Olderog for a language without recursion or internal moves. Moreover, Rutten investigated the semantics of a language similar to , in the framework of complete metric spaces, and showed that the failures model is fully abstract w. r. t. a strong linear semantics L, where L is strong in that it does not abstract from internal moves. The full abstractness of RF w. r. t. CWL, expressed in (*) with ,RF,CWL, is an extension of the result of Bergstra et al. to a language with recursion and internal moves. Also, the full abstractness of IRF w. r. t. IWL, expressed in (*) with ,IRF,IWL, is an extension of the Rutten's result, to the case of weak linear semantics with divergence.

Based on the semiclassical theory, we deduce the expressions of stimulated absorption, stimulated amplification and threshold by using density matrix equation in the Er3+-doped fibers. Meaningful results have been given and some phenomena occuring in experiments are explained theoretically.