Abstract:In this paper we introduce the concept on ω-NTB (ω-Nonterminal Bounded) grammars and their rank and prove that class of ω-NTB languages is identical with the class of ω-ultralinear languages. Moreover, we present some properties on the rank of ω-NTB grammars.

Abstract:In this paper, we gave a formal model of OS based on Petri Nets, it transformed the deadlock problem into linear algebric problem. We obtained a sufficient and necessary condition of deadlock existence in OS, and an optimal method which removed all deadlocks and guaranteed the regular operation in the system. Specialling, for distributed OS, we have greatly improved the method of detect deadlock.

Abstract:This paper introduces 2-D EAG method for hand printed Chinese character recognition. The main works are: Propose Two-Dimensional Extended Attribute Grammar (2-D EAG for short) method, in which both bottom-up reduction And top-down deduction are realized for two-way information transmitting and control; Propose a recognition scheme utilizing directly two dimensional information, to avoid information losses caused by linearization of features; Provide polysemous grammars, coexisting grammars and structure inferrigs which build special linkages among grammars and distinguish among similat samples by structural analogy;Besides,realize also redundant reduction scheme,stroks segment drawing algorithm with elastic tracing of contour lines, lines and redundant guided component drawing algorithm.The recognition experiment with 100 categories of hand printed Chinese characters is conducted and very good result is achieved in overcoming large scale strural distortions(including some cursive writings).

Abstract:That how to enable knowledge base to have the function of inference and maintenance automatically has been a key problem, which existed in the design of the knowledge base that wants to be practical and effective. In this paper, we propose an automatical knowledge base inference and maintenance method based on default inference at first, and then we introduce a knowledge base inference and maintenance system, which has been implemented on VAX-11/780 machine in GKD-Prolog.

Abstract:It is essential and pressing to improve rebobility of Boolean operations in geometric modelling systems. The Boolean operations in commercial systems now available are not reliable enough because of numerical calculation errors. Numerical calculation errors make us unable to determine set membership classifications exactly. Some classifications are ambiguous because they are dependent on adopted computing tolerance. Thereby interrelated classifications may conflict with each other and it is very difficult to get correct results of Boolean operations in many cases.We introduce a reliable Boolean opration algorithm which solves the conflicts among interrelated classifcations before implementation of Boolean operation by use of reasoning technique.The algorithm has replaced the modelling module of the geometric modelling system GEMS 2.0 to forma new system CEMS 2.1 on Apollo and Sun workstations.According totests and compared with Geomod 3.9 and I/EMS,CEMS 2.1 is much more reliable.

Abstract:To transform source program into flowchart is a research subject of software engineering. This paper gives a method and implementation techniques to transform source program to structured flowchart (PAD diagram). And they have been applied to transforming tool IPADT system. This paper also discusses some problems in transforming.

Abstract:Petri Net is an important model to discribe and analyse dynamic features of cocurrent systems. With further research of Petri Net theory and application to various practical areas, it is necessary to develop CAD tools which can support design and analysis of Petri Net. GPNT (Graphic Petri Net Tools) is a Petri Net tool made by Computer Science Department of Northwest University of China. It is used to assist the design, dynamic simulation and analysis of P/T Net. This paper briefly introduces the functions of GPNT and discusses some technical problems in the design and implementation of it.

Abstract:This paper gives an introduction to the communication system CS of the distributed data base management system POREL, it was implemented on the VAX/750 computer and the operating system UNIX in the application information institute of the vienna technical university in January, 1987 by writer.

Abstract:This paper provides a lexicographic sort algorithm. Using a new build formula to divide strings into groups and to form an index. Algorathm sort a sequence of n elements in O(n) expected time. In an essential manner, without the comparison between the elements in traditional algorithm. The new method uses the new formula to calculate, getting the result of the sort directly.