A new deductive approach to planning

We introduce a new deductive approach to planning which is based on Horn clauses. Plans as well as situations are represented as terms and, thus, are first-class objects. We do neither need frame axioms nor state-literals. The only rule of inference is the SLDE-resolution rule, i.e. SLD-resolution, where the traditional unification algorithm has been replaced by anE-unification procedure. We exemplify the properties of our method such as forward and backward reasoning, plan checking, and the integration of general theories. Finally, we present the calculus and show that it is sound and complete. An earlier version of this paper was presented at the German Workshop on Artificial Intelligence, 1989.     

Eliminability of cut in hypersequent calculi for some modal logics of linear frames

Hypersequent calculi, introduced independently by Pottinger and Avron, provide a powerful generalization of ordinary sequent calculi. In the paper we present a proof of eliminability of cut in hypersequent calculi for three modal logics of linear frames: K4.3, KD4.3 and S4.3. Our cut-free calculus is based on Avron's HC formalization for Gödel–Dummett's logic. The presented proof of eliminability of cut is purely syntactical and based on Ciabattoni, Metcalfe, Montagna's proof of eliminability of cut for hypersequent calculi for some fuzzy logics with modalities.     

The effect of operators on parsing and evaluation in APL

The importance of function valued functions (operators) in APL is now well recognized, and considerable attention has been paid to the introduction of more general operators into the language. In this article we consider some of the consequences for the implementation of interpreters and compilers for APL.We first consider the difficulties that arise with the introduction of basic valued and operator valued operators. We then discuss various modifications to the syntactic and semantic structure of APL that serve to avoid these difficulties. Abstraction operators as in the λ calculus are also introduced. Finally, we describe an abstract machine for interpreting APL-like expressions which is analogous to the SECD machine used in the λ calculus.     

IMC: A Method for Interval Calculus in Matrix

Time representation is important in many applications, such as temporal databases, planning, and multi-agents. Since Allen’s work on binary interval relations (called interval algebra), many researchers have further investigated temporal information processing based on interval calculus. However, there are still some limitations, e.g. constraint satisfaction is a NP-hard problem in interval calculus. For this reason, we propose a new interpretation for interval relationships and their calculus in this paper, which establishes a new method to transform interval calculus into matrix calculus. Our experiments show that this method propagates temporal relations faster than interval algebra.     

A Polymorphic Environment Calculus and its Type-Inference Algorithm

The polymorphic environment calculus is a polymorphic lambda calculus which enables us to treat environments as first-class citizens. In the calculus, environments are formalized as explicit substitutions, and the substitutions are included in the set of terms of the calculus. First, we introduce an untyped environment calculus, and we present a semantics of the calculus as a translation into the lambda calculus. Second, we propose a polymorphic type system for the environment calculus based on Damas-Milner's ML-polymorphic type system. In ML, polymorphism is allowed only in let-expressions; in the polymorphic environment calculus, polymorphism is provided with environment compositions. We prove a subject-reduction theorem for the type system. Third, a type-inference algorithm is given to the polymorphic environment calculus, and we establish its soundness, termination, and principal-typing theorem.     

Timed Concurrent Constraint Programming for Analysing Biological Systems

In this paper we present our first approach to model and verify biological systems using ntcc, a concurrent constraint process calculus. We argue that the partial information constructs in ntcc can provide a suitable language for such systems. We also illustrate how ntcc may provide a unified framework for the analysis of biological systems, as they can be described, simulated and verified using the elements provided by the calculus.     

DDFP语言的归约机实现技术

ＤＤＦＰ语言是一种基于表达式的泛函程序设计语言，这是一种具有归约语义的，引用透明的，能表达无限数据结构，高阶纯粹的函数式语言。它的实现是基于λ演算、ＳＬＩ演算、ＳＫＬ－Ｇ演算、ＬＮＦ演算及图归约技术。本文在［４］的基础上首先引进了ＬＮＦ演算，而后详细介绍了该语言的归约机实现技术，对结果作了讨论。     

一种可行的自动程序理解途径

自动程序理解是软件工程和人工智能的非常活跃的研究领域，本文提出了一种独立于程序设计语言，具有明显结构性和流图结构的中间表示ｐｌａｎ来表示程序代码，本文首次提出了应用图文法分析技术于自动程序理解的方法，并给出了基于人工智能技术来进行自动程序理解的模型。     

The Variety of Variables in Computer-Aided Real-Time Programming

The refinement calculus is a well-established theory for translating specifications to program code. Recent research has extended the calculus to handle real-time requirements and we have developed an interactive support tool based on these extensions. Via a case study, this paper shows how the tool helps the programmer by supporting the many forms of variables used in the theory. These include simple state variables as in the untimed calculus, timed-trace variables that model the evolution of properties over time, and auxiliary variables that exist to support formal reasoning only.     

基于Spi演算的SSL3.0安全协议仿真分析

安全协议中的错误和漏洞很难完全由人工来发现,借助形式化方法对其进行分析可以保证安全协议的正确件和完整性。目前安全协议的形式化分析和验证已成为网络安全的研究热点,其中基于Spi演算的模型验证方法足当前的一个重要研究领域。文章介绍了SSL3．0安全协议的握手过程和Spi演算的基本概念,包括基于spi演算认证性的验证方法。存此基础上,基于spi演算形式化地建立了SSL3．0安全协议的仿真模型,给出了分析SSL3．0安全协议的详细过程,最终验证了SSL3．0安令协议的认证性。仿真分析的结果表明,Spi演算能够为安全协议的分析和验证提供可靠和有效的支持。     

Integrating Discrete and Continuous Change in a Logical Framework

The goal of our work is to develop theoretical foundations for the representation of knowledge in domains in which properties may vary continuously. One achievement of our research is that it extends the applicability of current research on theories of action. Furthermore, we are able to apply known approaches to the frame and ramification problems, developed for discretely changing worlds, to domains in which the world changes continuously.
Our approach is based on the discrete situation calculus and on a monotonic solution to the frame problem. In order to address the combined frame and ramification problems, we extend Lin and Reiter's work. We use Pinto and Reiter's extension to the situation calculus to represent occurrences . We extend this work further to allow for reasoning by default. For example, if we know that a ball is falling and we do not have any reason to believe that an action would interfere with the ball's motion, then we assume that the ball will hit the ground. Finally, we extend the language of the situation calculus to allow for properties that change within situations. We also show that our proposed situation calculus inherits the solutions to the frame and ramification problems.     

次协调数据库中的域关系演算

次协调数据库的数据模型是用来处理数据库中两类不确定信息,即不完全信息和不一致信息(矛盾信息)。关系演算语言是表达关系数据模型中的数据操作的一种方式。域关系演算是以域为变量进行的关系演算。文中提出了一种4值的域关系演算来查询次协调数据库,它的语法与普通关系上的2值域关系演算相似,但是这种新的4值语义能够有效的查询不完全信息和不一致信息。这为次协调数据库中的类SQL语言及实现提供了理论依据,进而为次协调数据库的应用打下坚实基础。     

A Dynamic Logic for deductive verification of multi-threaded programs

We present MODL, a Dynamic Logic and a deductive verification calculus for a core Java-like language that includes multi-threading. The calculus is based on symbolic execution. Even though we currently do not handle non-atomic loops, employing the technique of symmetry reduction allows us to verify systems without limits on state space or thread number. We have instantiated our logic for (restricted) multi-threaded Java programs and implemented the verification calculus within the KeY system. We demonstrate our approach by verifying a central method of the StringBuffer class from the Java standard library in the presence of unbounded concurrency.     

Controlled Use of Clausal Lemmas in Connection Tableau Calculi

Proof procedures based on model elimination or the connection tableau calculus have become more and more successful. But these procedures still suffer from long proof lengths as well as from a rather high degree of redundant search effort in comparison with resolution-style search procedures. In order to overcome these problems we investigate the use of clausal lemmas. We develop a method to augment a given set of clauses by a lemma set in a preprocessing phase and discuss the ability of this technique to reduce proof lengths and depths and to provide an appropriate reordering of the search space. We deal with the basic connection tableau calculus as well as with several calculus refinements and extensions. In order to control the use of lemmas we develop techniques for selecting relevant lemmas based on partial evaluation techniques. Experiments with the prover Setheo performed in several domains demonstrate the high potential of our approach.     

A formalization of absolute and relative dates based on the point calculus

In this paper we present a formalization of absolute and relative dates based on a formalization of the point calculus. We discuss three extensions of the point calculus, namely absolute dates, relative dates and both kinds of dates. An approach to translate the point calculus with relative dates to a tense logic is suggested.     

Program testing by specification mutation

Both theoretical and empirical arguments suggest that specifications and implementations are equally important sources of information for generating test cases. Nevertheless, the majority of test generation procedures described in the literature deal only with the program source, ignoring specifications. In this paper we outline a procedure for measuring test case effectiveness using specifications given in predicate calculus form. This method is similar to the mutation analysis method of testing programs.     

Ambient演算的数据流分析方法及其实现

针对Ambient演算的定义,提出了Ambient演算语法结构树的概念,并且给出一个基于Ambient语法结构树的Ambient演算的数据流分析方法及其实现。为深入研究Ambient演算的性质和应用提供了分析手段。     

External Rewriting for Skeptical Proof Assistants

This paper presents the design, the implementation, and experiments of the integration of syntactic, conditional possibly associative-commutative term rewriting into proof assistants based on constructive type theory. Our approach is called external because it consists in performing term rewriting in a specific and efficient environment and checking the computations later in a proof assistant. Two typical systems are considered in this work: ELAN, based on the rewriting calculus, as the term rewriting-based environment, and Coq, based on the calculus of inductive constructions as the proof assistant. We first formalize the proof terms for deduction by rewriting and strategies in ELAN using the rewriting calculus with explicit substitutions. We then show how these proof terms can soundly be translated into Coq syntax where they can be directly type checked. For the method to be applicable for rewriting modulo associativity and commutativity, we provide an effective method to prove equalities modulo these axioms in Coq using ELAN. These results have been integrated into an ELAN-based rewriting tactic in Coq.     

Connection Tableaux with Lazy Paramodulation

It is well known that the connection refinement of clause tableaux with paramodulation is incomplete (even with weak connections). In this paper, we present a new connection tableau calculus for logic with equality. This calculus is based on a lazy form of paramodulation where parts of the unification step become auxiliary subgoals in a tableau and may be subjected to subsequent paramodulations. Our calculus uses ordering constraints and a certain form of the basicness restriction.     

基于流演算的多Agent通信动作的研究

为扩展多Agent系统中Agents之间的交互特性,在流演算理论框架下研究了多Agent的通信动作.根据流演算理论和主体通信语言ACL,结合其它Agent的知识表示,引入了通信动作,给出了形式化描述,并讨论了通信动作如何影响通信双方的知识状态,并通过一个智能日程安排实例验证了上述理论,为构建适应动态.不完全可知环境下复杂的多主体系统提供了理论基础.