Reasoning about time in the situation calculus

We extend the ontology of the situation calculus to provide for the representation of time and event occurrences. We do this by defining a time line corresponding to a sequence of situations (calledactual situations) beginning with the initial situation. Actual situations are totally ordered and the actions that lead to different actual situations are said to haveoccurred. This extension to the situation calculus permits one to express truths about the state of the world at different times. For example, we can state that at some point in the future certain fluents will be true. We can also express constraints on the occurrences of events, for example, that after releasing a cup, it will eventually hit the floor. Our version of the situation calculus subsumes other temporal logics. In particular, we show that the modaltemporal logic of concurrency [4] can be embedded in the extended situation calculus. Our extension can also realize the essential features of other first-order proposals for reasoning about time commonly used for AI purposes (e.g. Allen [1], Kowalski and Sergot [6]).Part of this work was done while this author was with the Department of Computer Science, University of Toronto.     

Reasoning about software using metrics and expert opinion

When comparing software programs on the basis of more than one metric a difficulty arises when the metrics are contradictory or if there are no standard acceptance thresholds. An appealing solution in such cases is to incorporate expert opinion to resolve the inconsistencies. A rigorous framework, however, is essential when fusing metrics and expert opinion in this decision-making process. Fortunately, the analytical hierarchy process (AHP) can be used to facilitate rigorous decision-making in this particular problem. In this work a combination of expert opinion and tool-collected measures are used to reason about software programs using AHP. The methodology employed can be adapted to other decision-making problems in software engineering when both metrics data and expert opinion are available, some of which are described. This paper is an extended version of Norita Ahmad and Phillip A. Laplante, “Employing Expert Opinion and Software Metrics for Reasoning About Software,” Third IEEE International Symposium on Dependable, Autonomic and Secure Computing (DASC 2007), September 2007, Columbia, Maryland, USA.     

高级语言和组态软件对设计PC机与PLC通讯程序的比较

本文就PC机和PLC通讯机制进行了简要介绍,在此基础上阐述了具体实现方法,即主要通过高级语言和组态软件两种办法。并就二者具体实现进行了介绍和比较,指出了两种方法存在的优缺点。     

Reasoning about programs

This paper describes a theorem prover that embodies knowledge about programming constructs, such as numbers, arrays, lists, and expressions. The program can reason about these concepts and is used as part of a program verification system that uses the Floyd-Naur explication of program semantics. It is implemented in the qa4 language; the qa4 system allows many pieces of strategic knowledge, each expressed as a small program, to be coordinated so that a program stands forward when it is relevant to the problem at hand. The language allows clear, concise representation of this sort of knowledge. The qa4 system also has special facilities for dealing with commutative functions, ordering relations, and equivalence relations; these features are heavily used in this deductive system. The program interrogates the user and asks his advice in the course of a proof. Verifications have been found for Hoare's FIND program, a real-number division algorithm, and some sort programs, as well as for many simpler algorithms. Additional theorems have been proved about a pattern matcher and a version of Robinson's unification algorithm. The appendix contains a complete, annotated listing of the deductive system and annotated traces of several of the deductions performed by the system.     

Reasoning about equality

This note contains a set of six theorems that can be used to assess the ability of a theorem-proving system to reason about equality. The six theorems are graduated in terms of difficulty: they range from fairly trivial to quite difficult. They do not cover all aspects of equality reasoning, but they have proved useful to us in developing our system.This work was supported in part by National Science Foundation grant MCS82-07496 and in part by the Applied Mathematical Sciences Research Program (KC-04-02) of the Office of Energy Research of the U.S. Department of Energy under Contract W-31-109-Eng-38.     

Thinking about Reasoning about Knowledge

Minds and Machines -     

Reasoning about memory layouts

Verification methods for memory-manipulating C programs need to address not only well-typed programs that respect invariants such as the split-heap memory model, but also programs that access through pointers arbitrary memory objects such as local variables, single struct fields, or array slices. We present a logic for memory layouts that covers these applications and show how proof obligations arising during the verification can be discharged automatically using the layouts. The framework developed in this way is also suitable for reasoning about data structures manipulated by algorithms, which we demonstrate by verifying the Schorr-Waite graph marking algorithm.     

Reasoning about emotional agents

In this article we discuss the role of emotions in artificial agent design, and the use of logic in reasoning about the emotional or affective states an agent can reside in. We do so by extending the KARO framework for reasoning about rational agents appropriately. In particular, we formalize in this framework how emotions are related to the action monitoring capabilities of an agent. © 2006 Wiley Periodicals, Inc. Int J Int Syst 21: 601–619, 2006.     

Reasoning algebraically about loops

We show how to formalise different kinds of loop constructs within the refinement calculus, and how to use this formalisation to derive general transformation rules for loop constructs. The emphasis is on using algebraic methods for reasoning about equivalence and refinement of loop constructs, rather than operational ways of reasoning about loops in terms of their execution sequences. We apply the algebraic reasoning techniques to derive a collection of transformation rules for action systems and for guarded loops. These include transformation rules that have been found important in practical program derivations: data refinement and atomicity refinement of action systems; and merging, reordering, and data refinement of loops with stuttering transitions. Received: 11 February 1998 / 18 March 1999     

Reasoning about Information Change

In this paper we introduce Dynamic Epistemic Logic, which is alogic for reasoning about information change in a multi-agent system. Theinformation structures we use are based on non-well-founded sets, and canbe conceived as bisimulation classes of Kripke models. On these structures,we define a notion of information change that is inspired by UpdateSemantics (Veltman, 1996). We give a sound and complete axiomatization ofthe resulting logic, and we discuss applications to the puzzle of the dirtychildren, and to knowledge programs.     

Reasoning about coalitional games

We develop, investigate, and compare two logic-based knowledge representation formalisms for reasoning about coalitional games. The main constructs of Coalitional Game Logic (cgl) are expressions for representing the ability of coalitions, which may be combined with expressions for representing the preferences that agents have over outcomes. Modal Coalitional Game Logic (mcgl) is a normal modal logic, in which the main construct is a modality for expressing the preferences of groups of agents. For both frameworks, we give complete axiomatisations, and show how they can be used to characterise solution concepts for coalitional games. We show that, while cgl is more expressive than mcgl, the former can only be used to reason about coalitional games with finitely many outcomes, while mcgl can be used to reason also about games with infinitely many outcomes, and is in addition more succinct. We characterise the computational complexity of satisfiability for cgl, and give a tableaux-based decision procedure.     

Reasoning about interactive system

Interactive systems have goals and characteristics that differ from those of batch systems. These differences lead to a need for new techniques, methods, and tools for manipulating and constructing interactive systems. The difference in structure between batch and interactive systems. The difference is considered, focusing on the distinction between command decomposition and component decomposition. The possible ways of solving a problem using an interactive system using action paths, which account for the relatively unconstrained actions of interactive users, are described. It is shown that interactivity is not an inherent characteristic of a system but rather a characteristic that depends on the error profile of its users. The requirements that interaction places on the underlying implementation, specifically the need for incrementality and integration, are considered. The results are applied to several existing classes of systems     

Reasoning about agent deliberation

We present a family of sound and complete logics for reasoning about deliberation strategies for SimpleAPL programs. SimpleAPL is a fragment of the agent programming language 3APL designed for the implementation of cognitive agents with beliefs, goals and plans. The logics are variants of PDL, and allow us to prove safety and liveness properties of SimpleAPL agent programs under different deliberation strategies. We show how to axiomatise different deliberation strategies for SimpleAPL programs, and, for each strategy we prove a correspondence between the operational semantics of SimpleAPL and the models of the corresponding logic. We illustrate the utility of our approach with an example in which we show how to verify correctness properties for a simple agent program under different deliberation strategies.     

Reasoning about synchronization in GALS systems

Correct design of interface circuits is crucial for the development of System-on-Chips (SoC) using off-the-shelf IP cores. For correct operation, an interface circuit must meet strict synchronization timing constraints, and also respect sequencing constraints between events dictated by interfacing protocols and rational clock relations. In this paper, we propose a technique for automatically analyzing the interaction between independently specified synchronization constraints and sequencing constraints between events. We show how this analysis can be used to derive delay constraints for correct operation of interface circuits in a GALS system. Our methodology allows an SoC designer to mix and match different interfacing protocols, rational clock relations and synchronization constraints for communication between a pair of modules, and automatically explore their implications on correct interface circuit design.     

Reasoning about preferences in argumentation frameworks

The abstract nature of Dung's seminal theory of argumentation accounts for its widespread application as a general framework for various species of non-monotonic reasoning, and, more generally, reasoning in the presence of conflict. A Dung argumentation framework is instantiated by arguments and a binary conflict based attack relation, defined by some underlying logical theory. The justified arguments under different extensional semantics are then evaluated, and the claims of these arguments define the inferences of the underlying theory. To determine a unique set of justified arguments often requires a preference relation on arguments to determine the success of attacks between arguments. However, preference information is often itself defeasible, conflicting and so subject to argumentation. Hence, in this paper we extend Dung's theory to accommodate arguments that claim preferences between other arguments, thus incorporating meta-level argumentation based reasoning about preferences in the object level. We then define and study application of the full range of Dung's extensional semantics to the extended framework, and study special classes of the extended framework. The extended theory preserves the abstract nature of Dung's approach, thus aiming at a general framework for non-monotonic formalisms that accommodate defeasible reasoning about as well as with preference information. We illustrate by formalising argument based logic programming with defeasible priorities in the extended theory.     

基于Object-Z多态推理

Object-Z是形式规格说明语言Z的面向对象扩充,基于严格的集合论与数理逻辑,具有面向对象的特点：类、对象、继承、封装与多态等。用它可以精确描述大型软件需求规格说明,且能够进行严密的逻辑推理与验证。本文主要探讨了它的多态性推理,给出了相应的推理规则与方法,可以推理出Object-Z的多态行为,并着重体现推理的重用。