Congruent Weak Conformance

This research addresses the problem of verifying implementations against specifications through an innovative logic approach. Congruent weak conformance, a formal relationship between agents and specifications, has been developed and proven to be a congruent partial order. This property arises from a set of relations called weak conformations. The largest, called weak conformance, is analogous to Milner\u27s observational equivalence. Weak conformance is not an equivalence, however, but rather an ordering relation among processes. Weak conformance allows behaviors in the implementation that are unreachable in the specification. Furthermore, it exploits output concurrencies and allows interleaving of extraneous output actions in the implementation. Finally, reasonable restrictions in CCS syntax strengthen weak conformance to a congruence, called congruent weak conformance. At present, congruent weak conformance is the best known formal relation for verifying implementations against specifications. This precongruence derives maximal flexibility and embodies all weaknesses in input, output, and no-connect signals while retaining a fully replaceable conformance to the specification. Congruent weak conformance has additional utility in verifying transformations between systems of incompatible semantics. This dissertation describes a hypothetical translator from the informal simulation semantics of VHDL to the bisimulation semantics of CCS. A second translator is described from VHDL to a broadcast-communication version of CCS. By showing that they preserve congruent weak conformance, both translators are verified

Integrating deductive verification and symbolic execution for abstract object creation in dynamic logic

We present a fully abstract weakest precondition calculus and its integration with symbolic execution. Our assertion language allows both specifying and verifying properties of objects at the abstraction level of the programming language, abstracting from a specific implementation of object creation. Objects which are not (yet) created never play any role. The corresponding proof theory is discussed and justified formally by soundness theorems. The usage of the assertion language and proof rules is illustrated with an example of a linked list reachability property. All proof rules presented are fully implemented in a version of the KeY verification system for Java programs

'Difficulty' In Text As A Function Of Syntactic Complexity: A Study Of Syntactic Complexity Within And Between Sentences

This work proposes possible categories for analysing complexity in English text. Particular attention is paid to the following categories: the long subject construction, the nominal group, the appositional group, and interpolation structures. These categories are analysed in relation to two dimensions of text: firstly, in relation to the individual sentence, and secondly, in relation to the larger discourse context of clause relations. (A clause relation is a binary relation between members. Each member consists of one or more clauses or sentences). The first dimension examines how the presence of these categories functions to interrupt the structure of the clause as a minimal grammatical form. It is assumed that the structure of the clause is basic to the structure of text and is central to the reading process, When the structure of the clause is interrupted excessively by these categories, it is predicted that there will be a consequent impairment of reading comprehension. The second dimension of complexity examines how the structural interruption of the individual sentence can entail the structural interruption of the clause relation. Syntactic complexity at this level of structure is increased when the minimal grammatical form of the clause relation (that is, the relation between two members) is delayed excessively by structural interruption. Thus, although the individual clause is the primary unit of description in this analysis of complexity, the analysis is not restricted to the single sentence. Moreover, the individual categories proposed are descriptive procedures which derive from the examination of texts as aspects of performance, not as aspects of competence. Finally, the notion of clause is put forward as a grammatical constraint which has important implications for our production of texts. The clause is fundamental to the structure of texts and provides the mechanism for its cohesion

An Analysis of Three Approaches to Grammar with Recommendations for a Multiphasal Grammar

Today the teacher is confronted with three approaches to the teaching of grammar, all of which contain useful concepts; it is the major contention of this study that the best of each of these approaches may be the desired choice. It is the intention of this paper to propose a multiphasal grammar and to show that such a grammar seems to be the ultimate direction for the teaching of the English language. This multiphasal grammar will combine the best of the three approaches: the most useful and logical elements of traditional nomenclature; the structuralists\u27 emphasis on the sound of language, based on the three mechanisms of intonation: pitch, stress, and juncture, as well as their attitude toward uniform correctness; and the transformational approach to syntax. This author believes that a multiphasal grammar will be more teachable, more efficient, and better received in the public school than the grammar, basically traditional, that is being taught today. For decades, the word grammar has had a distasteful connotation. Teachers as well as students find the study of grammar boring and generally unproductive through no fault of the subject matter; rather the fault lies in antiquated and basically inadequate techniques and approaches. (See more in text

Adjustment Strategies for Non-Compliant Process Instances

Enabling changes at both process type and process instance level is an essential requirement for any adaptive process-aware information system (PAIS). Particularly, it should be possible to migrate a (long-)running process instance to a new type schema version, even if this instance has been individually modified before. Further instance migration must not violate soundness; i.e., structural and behavorial consistency need to be preserved. Compliance has been introduced as basic notion to ensure that instances, whose state has progressed too far, are prohibited from being migrated. However, this also excludes them from further process optimizations, which is not tolerable in many practical settings. This paper introduces a number of strategies for coping with non-compliant instances in the context of process change such that they can benefit from future process type changes on the one hand, but do not run into soundness problems on the other hand. We show, for example, how to automatically adjust process type changes at instance level to enable the migration of a higher number of instances. The different strategies are compared and discussed along existing approaches. Altogether, adequate treatment of non-compliant process instances contributes to full process lifecycle support in adaptive PAIS